anuaay/fe ruary 2002 - gear · pdf filejanuary/february 2002 the journal of ... powder...
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ANUAAYfE RUARY 2002
Bevel gear cuttingenters a new era withthe Phoenix II 275HCCNC BevelGearCutting Maeblne
New 600HTT TURBQTESTERtrade performs fasterCNC roll testing_ of spiraland by-p1oid bevel gear sets
IIs 35 smaJler than the Phoenix175HC but produce part withdiameters up to 275 rnrn cuts drywithout chip shrouds andvacuum systems simplifies andspeeds part loadunload andcuner changeover and featuresdirect-drive pindle motors forfaster setup and machining time
lI features a small footprint ergonomicand easy-la-use design performs not onlybasic pattern checking but also SFT (SingleRank T-ransmission error) testing and
SBN (Structure-Borne-Noise) te ting andaccommodates workpiece diameters lip to 600 mrn
Thank to a breakthroughmonolithic column designullof these user benefits are nowavailable and much more
The 600HTT TURBO TESTER~ also shares thearne platform made popular with the recent
introduction of the 600HTL TUR130 LAPP_ Ro you benefit from vast reductions in floorspace
and a highly accessible work chamber
HID UDive ity Ave lPOBox 22970Rochester NY 14692-2970 USA
Phone 585473-1(0) fax 5851461-4348Web site wwwgleasoncom E-mail salesgleasonoomCIACIE 110
Tlhe Glleason Works
SUPERIORQUALITY SERVICEAND DELIVERY
JANUARYFEBRUARY 2002 The Journal of Gear Manufacturing
FEATURES
IConsideration 01Moving Toolh load inGear Crack Propagation PredictionsHow moving tooth load affects fatigue crack growth trajectory 14
FOCUS ON ALTERNATIVE GEAR MANUFACTURING
DEPARTMENTS
Net-Shaped forged GieallS-The State of the AnThe latest technology for forging spur helical bevel and spiral bevel gears 26
falilure Mechanisms in Plastic IGearsExperiments all and analysis of nylon gears 311
Technology lid bitsNews and information on alternative gear manufacturing technologie 31
a t h 9 e a r s ph e 9 0 Y IJ b m iV a f a b e d e nt r i n f b i n II
Ii r i p p I i n 9
I~ s n i n Cl h n eI f 9 h h u j n 9r a c k e u g i tt b Y n II j h h 9n b i d il d x d d
Cover art coulllesy oJMetalPowder Industries federationPrinceton NJ
IPublishers PageCyber-Seminars A Virtual Success 7
IBoak IReviewTile Gear Analysis Handbook by James L Taylor 8
IRevolutionsPrize winners at Gear Expo and grinding by broaching nIndustrv NewsWhal happening in the gear industry 411
Product NewsThe latest products for the gear industry 42
TechOlicalCalendarDont miss these important upcoming events 43
Letterto the EditorRevi iting the personal touch in business 44
ClassifiedsServices Help Wanted and more 46
AddendumGear middotWord Search 48
2301 Curtiss Streetmiddot Downer GroveIt 60515Tel (630) 969-7640 bull faJC (630) 969-0253
wwwlTowgearcom
CIRCllE 166
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Website httpifwww leclluntcom (includes product speciificatiDnsl
CIRCLE 164
4 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgllllechnologycom 0 wwwpowerlmiddotfllllsmssoncom
EDITORIALPublisher amp Edltor-iu-Chief
Michael Goldstein
Managing Editor William R SIOlt
Associate Editor Joseph L Hazelton
Editorial Consultant Paul R Goldstein
Technical EditorRobert Errichello
DOli McVitticRobert E SmithDan Thurman
ARTArt Director lean Bartz
ADVERTISINGAdvertising Manager Patricia Flam
Advertising Coordinator Gladyce J Cooper
CIRCULATIIONCireuladon Coordinator Dina Krauss
INTERNETWeb Developer Dan MacKenzie
Gear Industry Home Pagelgt SalesPatricia FlamDavid Tornalis
RANDAU PUBLlSHlliNG STAfFPresident Michael Goldstein
Vice President Richard GoldsteinControUer Michael Grafman
Accounting Dianne Johnson
Phone 847-437-6604EmailmiddotpeoplegeartecJanologycom
Web wwwgeartechnology comwwwpowertransmisrioncom
VOL 19 NO 1GEAR TECILlOLOGY The Jour of GtarManuracturing (ISSN 0143~685S) is published bimonth-[1 b~ RomWl Publishing lnc 1425 Lam Avenu e PDBo 1426 EIk Gro Village IL 60001 (841) 43](604Cltt ve r price S500 US Periodical postage pmd trtin HeIghtlt 11 altlltlat odltIilioooI mallin~ m~Randall Publishing makes every effort to ensure ht theprocessev described in GEAR TECHNOLOGY conform10 sound engineering practice Neither Ihe au~ho~ nor thepublisher can be held responsible fer injuries iiultta3nedwhlle faUn-wing the procedures dascribed PostmasterSend uddress changes [0 GEAR JECHNOLOGY TheJournal of Gear Manufacturing 1425 Lunt Aven e PO130 1416 Elk Gmv ViILgoL 60007 OCQntefl copyrighted hy RANDALL PUBLISHING INC bull 2002 Nopm of Lhi publicelon may be reproduced or eensmtuedill any forrn or by Wly means eieeuente or mecbarucaJmduding phoeocupying recording or by any mformllllon
nd reirieval sYSICmwitoom permi ion in iIInl-the publisher Ccmems of ads = ubjltd to
I s PJIO3L
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Uke steel Dura-Bar can beaustemperedthrough-hardened flame-hardeaed or induction-hardened for added wear resistance But thesuperior noise and vibration damping eharacteristiesofDura-Bar make for quieter runninggears And Dura-Bar Is 10 lighter than steel
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CIRCLE 158
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CIRCLE 114
1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
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cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
When big th-ngs are onthe mov
fasslerCorporation131W Layton Avenue Suite 308Milwaukee WI 53207Phone (414) 769-0072Fax (414) 769-8610E-mail fasslerexecpccom
internall spllnes
bull wwwfaessller-agchCIRClE 119
The Gear Technology Buyers Guide 2002
COPIES STILL AVAILABLEThe Complete Geilr Industry on CD-ROM
bull Machines bull Cutting Toolsbull Services Gear Manufacture rs
bull Gea r Drive Manuf eturers
Everything you need to make or buy gea rsGet your eXIra copy today
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
Provides vital SPCinformation
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CIRCLE 12310 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnoogycom bull wwwpowertransmfssloncom
IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
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For mora information contact
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
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Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
Bevel gear cuttingenters a new era withthe Phoenix II 275HCCNC BevelGearCutting Maeblne
New 600HTT TURBQTESTERtrade performs fasterCNC roll testing_ of spiraland by-p1oid bevel gear sets
IIs 35 smaJler than the Phoenix175HC but produce part withdiameters up to 275 rnrn cuts drywithout chip shrouds andvacuum systems simplifies andspeeds part loadunload andcuner changeover and featuresdirect-drive pindle motors forfaster setup and machining time
lI features a small footprint ergonomicand easy-la-use design performs not onlybasic pattern checking but also SFT (SingleRank T-ransmission error) testing and
SBN (Structure-Borne-Noise) te ting andaccommodates workpiece diameters lip to 600 mrn
Thank to a breakthroughmonolithic column designullof these user benefits are nowavailable and much more
The 600HTT TURBO TESTER~ also shares thearne platform made popular with the recent
introduction of the 600HTL TUR130 LAPP_ Ro you benefit from vast reductions in floorspace
and a highly accessible work chamber
HID UDive ity Ave lPOBox 22970Rochester NY 14692-2970 USA
Phone 585473-1(0) fax 5851461-4348Web site wwwgleasoncom E-mail salesgleasonoomCIACIE 110
Tlhe Glleason Works
SUPERIORQUALITY SERVICEAND DELIVERY
JANUARYFEBRUARY 2002 The Journal of Gear Manufacturing
FEATURES
IConsideration 01Moving Toolh load inGear Crack Propagation PredictionsHow moving tooth load affects fatigue crack growth trajectory 14
FOCUS ON ALTERNATIVE GEAR MANUFACTURING
DEPARTMENTS
Net-Shaped forged GieallS-The State of the AnThe latest technology for forging spur helical bevel and spiral bevel gears 26
falilure Mechanisms in Plastic IGearsExperiments all and analysis of nylon gears 311
Technology lid bitsNews and information on alternative gear manufacturing technologie 31
a t h 9 e a r s ph e 9 0 Y IJ b m iV a f a b e d e nt r i n f b i n II
Ii r i p p I i n 9
I~ s n i n Cl h n eI f 9 h h u j n 9r a c k e u g i tt b Y n II j h h 9n b i d il d x d d
Cover art coulllesy oJMetalPowder Industries federationPrinceton NJ
IPublishers PageCyber-Seminars A Virtual Success 7
IBoak IReviewTile Gear Analysis Handbook by James L Taylor 8
IRevolutionsPrize winners at Gear Expo and grinding by broaching nIndustrv NewsWhal happening in the gear industry 411
Product NewsThe latest products for the gear industry 42
TechOlicalCalendarDont miss these important upcoming events 43
Letterto the EditorRevi iting the personal touch in business 44
ClassifiedsServices Help Wanted and more 46
AddendumGear middotWord Search 48
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EDITORIALPublisher amp Edltor-iu-Chief
Michael Goldstein
Managing Editor William R SIOlt
Associate Editor Joseph L Hazelton
Editorial Consultant Paul R Goldstein
Technical EditorRobert Errichello
DOli McVitticRobert E SmithDan Thurman
ARTArt Director lean Bartz
ADVERTISINGAdvertising Manager Patricia Flam
Advertising Coordinator Gladyce J Cooper
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Vice President Richard GoldsteinControUer Michael Grafman
Accounting Dianne Johnson
Phone 847-437-6604EmailmiddotpeoplegeartecJanologycom
Web wwwgeartechnology comwwwpowertransmisrioncom
VOL 19 NO 1GEAR TECILlOLOGY The Jour of GtarManuracturing (ISSN 0143~685S) is published bimonth-[1 b~ RomWl Publishing lnc 1425 Lam Avenu e PDBo 1426 EIk Gro Village IL 60001 (841) 43](604Cltt ve r price S500 US Periodical postage pmd trtin HeIghtlt 11 altlltlat odltIilioooI mallin~ m~Randall Publishing makes every effort to ensure ht theprocessev described in GEAR TECHNOLOGY conform10 sound engineering practice Neither Ihe au~ho~ nor thepublisher can be held responsible fer injuries iiultta3nedwhlle faUn-wing the procedures dascribed PostmasterSend uddress changes [0 GEAR JECHNOLOGY TheJournal of Gear Manufacturing 1425 Lunt Aven e PO130 1416 Elk Gmv ViILgoL 60007 OCQntefl copyrighted hy RANDALL PUBLISHING INC bull 2002 Nopm of Lhi publicelon may be reproduced or eensmtuedill any forrn or by Wly means eieeuente or mecbarucaJmduding phoeocupying recording or by any mformllllon
nd reirieval sYSICmwitoom permi ion in iIInl-the publisher Ccmems of ads = ubjltd to
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1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
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cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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The new Mitsubishi Gear lechnology Centeris your siinsle source for the broadest arrayof gear production technoiogy in the worldFrom our patented high-speed dry cuttingmachines and hobs through gear shapersshavers and honing machinest to completestand-alonegear production centers
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If your current manu~acturingchallenges require the detailed focus of thewonds foremost authority on gear produc-tlonsive us a calliAfter alit were in theneighbo~hood
ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
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IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
PreciseProfiles
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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f h h
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
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CIRCLE 107
SUPERIORQUALITY SERVICEAND DELIVERY
JANUARYFEBRUARY 2002 The Journal of Gear Manufacturing
FEATURES
IConsideration 01Moving Toolh load inGear Crack Propagation PredictionsHow moving tooth load affects fatigue crack growth trajectory 14
FOCUS ON ALTERNATIVE GEAR MANUFACTURING
DEPARTMENTS
Net-Shaped forged GieallS-The State of the AnThe latest technology for forging spur helical bevel and spiral bevel gears 26
falilure Mechanisms in Plastic IGearsExperiments all and analysis of nylon gears 311
Technology lid bitsNews and information on alternative gear manufacturing technologie 31
a t h 9 e a r s ph e 9 0 Y IJ b m iV a f a b e d e nt r i n f b i n II
Ii r i p p I i n 9
I~ s n i n Cl h n eI f 9 h h u j n 9r a c k e u g i tt b Y n II j h h 9n b i d il d x d d
Cover art coulllesy oJMetalPowder Industries federationPrinceton NJ
IPublishers PageCyber-Seminars A Virtual Success 7
IBoak IReviewTile Gear Analysis Handbook by James L Taylor 8
IRevolutionsPrize winners at Gear Expo and grinding by broaching nIndustrv NewsWhal happening in the gear industry 411
Product NewsThe latest products for the gear industry 42
TechOlicalCalendarDont miss these important upcoming events 43
Letterto the EditorRevi iting the personal touch in business 44
ClassifiedsServices Help Wanted and more 46
AddendumGear middotWord Search 48
2301 Curtiss Streetmiddot Downer GroveIt 60515Tel (630) 969-7640 bull faJC (630) 969-0253
wwwlTowgearcom
CIRCllE 166
WANTEDMORE ACCURACY
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THE ANSWER FOR 1150 YEARS
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CIRCLE 164
4 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgllllechnologycom 0 wwwpowerlmiddotfllllsmssoncom
EDITORIALPublisher amp Edltor-iu-Chief
Michael Goldstein
Managing Editor William R SIOlt
Associate Editor Joseph L Hazelton
Editorial Consultant Paul R Goldstein
Technical EditorRobert Errichello
DOli McVitticRobert E SmithDan Thurman
ARTArt Director lean Bartz
ADVERTISINGAdvertising Manager Patricia Flam
Advertising Coordinator Gladyce J Cooper
CIRCULATIIONCireuladon Coordinator Dina Krauss
INTERNETWeb Developer Dan MacKenzie
Gear Industry Home Pagelgt SalesPatricia FlamDavid Tornalis
RANDAU PUBLlSHlliNG STAfFPresident Michael Goldstein
Vice President Richard GoldsteinControUer Michael Grafman
Accounting Dianne Johnson
Phone 847-437-6604EmailmiddotpeoplegeartecJanologycom
Web wwwgeartechnology comwwwpowertransmisrioncom
VOL 19 NO 1GEAR TECILlOLOGY The Jour of GtarManuracturing (ISSN 0143~685S) is published bimonth-[1 b~ RomWl Publishing lnc 1425 Lam Avenu e PDBo 1426 EIk Gro Village IL 60001 (841) 43](604Cltt ve r price S500 US Periodical postage pmd trtin HeIghtlt 11 altlltlat odltIilioooI mallin~ m~Randall Publishing makes every effort to ensure ht theprocessev described in GEAR TECHNOLOGY conform10 sound engineering practice Neither Ihe au~ho~ nor thepublisher can be held responsible fer injuries iiultta3nedwhlle faUn-wing the procedures dascribed PostmasterSend uddress changes [0 GEAR JECHNOLOGY TheJournal of Gear Manufacturing 1425 Lunt Aven e PO130 1416 Elk Gmv ViILgoL 60007 OCQntefl copyrighted hy RANDALL PUBLISHING INC bull 2002 Nopm of Lhi publicelon may be reproduced or eensmtuedill any forrn or by Wly means eieeuente or mecbarucaJmduding phoeocupying recording or by any mformllllon
nd reirieval sYSICmwitoom permi ion in iIInl-the publisher Ccmems of ads = ubjltd to
I s PJIO3L
Quieter GearsEngineered Metals
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Uke steel Dura-Bar can beaustemperedthrough-hardened flame-hardeaed or induction-hardened for added wear resistance But thesuperior noise and vibration damping eharacteristiesofDura-Bar make for quieter runninggears And Dura-Bar Is 10 lighter than steel
Dura-Bar round bars are available In diametersranging from 58 to 20 and lengths of 6middot20 So youwont need to make major changes in your machining equfpmentAnd our extensive Inventory means Dura-Bar is available nQW - when you need it
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CIRCLE 158
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CIRCLE 114
1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
TSUBAKIMOTIlCHAilN CO
RENDER CORP
cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
Provides vital SPCinformation
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
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WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
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IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
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CIRCLE 107
JANUARYFEBRUARY 2002 The Journal of Gear Manufacturing
FEATURES
IConsideration 01Moving Toolh load inGear Crack Propagation PredictionsHow moving tooth load affects fatigue crack growth trajectory 14
FOCUS ON ALTERNATIVE GEAR MANUFACTURING
DEPARTMENTS
Net-Shaped forged GieallS-The State of the AnThe latest technology for forging spur helical bevel and spiral bevel gears 26
falilure Mechanisms in Plastic IGearsExperiments all and analysis of nylon gears 311
Technology lid bitsNews and information on alternative gear manufacturing technologie 31
a t h 9 e a r s ph e 9 0 Y IJ b m iV a f a b e d e nt r i n f b i n II
Ii r i p p I i n 9
I~ s n i n Cl h n eI f 9 h h u j n 9r a c k e u g i tt b Y n II j h h 9n b i d il d x d d
Cover art coulllesy oJMetalPowder Industries federationPrinceton NJ
IPublishers PageCyber-Seminars A Virtual Success 7
IBoak IReviewTile Gear Analysis Handbook by James L Taylor 8
IRevolutionsPrize winners at Gear Expo and grinding by broaching nIndustrv NewsWhal happening in the gear industry 411
Product NewsThe latest products for the gear industry 42
TechOlicalCalendarDont miss these important upcoming events 43
Letterto the EditorRevi iting the personal touch in business 44
ClassifiedsServices Help Wanted and more 46
AddendumGear middotWord Search 48
2301 Curtiss Streetmiddot Downer GroveIt 60515Tel (630) 969-7640 bull faJC (630) 969-0253
wwwlTowgearcom
CIRCllE 166
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CIRCLE 164
4 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgllllechnologycom 0 wwwpowerlmiddotfllllsmssoncom
EDITORIALPublisher amp Edltor-iu-Chief
Michael Goldstein
Managing Editor William R SIOlt
Associate Editor Joseph L Hazelton
Editorial Consultant Paul R Goldstein
Technical EditorRobert Errichello
DOli McVitticRobert E SmithDan Thurman
ARTArt Director lean Bartz
ADVERTISINGAdvertising Manager Patricia Flam
Advertising Coordinator Gladyce J Cooper
CIRCULATIIONCireuladon Coordinator Dina Krauss
INTERNETWeb Developer Dan MacKenzie
Gear Industry Home Pagelgt SalesPatricia FlamDavid Tornalis
RANDAU PUBLlSHlliNG STAfFPresident Michael Goldstein
Vice President Richard GoldsteinControUer Michael Grafman
Accounting Dianne Johnson
Phone 847-437-6604EmailmiddotpeoplegeartecJanologycom
Web wwwgeartechnology comwwwpowertransmisrioncom
VOL 19 NO 1GEAR TECILlOLOGY The Jour of GtarManuracturing (ISSN 0143~685S) is published bimonth-[1 b~ RomWl Publishing lnc 1425 Lam Avenu e PDBo 1426 EIk Gro Village IL 60001 (841) 43](604Cltt ve r price S500 US Periodical postage pmd trtin HeIghtlt 11 altlltlat odltIilioooI mallin~ m~Randall Publishing makes every effort to ensure ht theprocessev described in GEAR TECHNOLOGY conform10 sound engineering practice Neither Ihe au~ho~ nor thepublisher can be held responsible fer injuries iiultta3nedwhlle faUn-wing the procedures dascribed PostmasterSend uddress changes [0 GEAR JECHNOLOGY TheJournal of Gear Manufacturing 1425 Lunt Aven e PO130 1416 Elk Gmv ViILgoL 60007 OCQntefl copyrighted hy RANDALL PUBLISHING INC bull 2002 Nopm of Lhi publicelon may be reproduced or eensmtuedill any forrn or by Wly means eieeuente or mecbarucaJmduding phoeocupying recording or by any mformllllon
nd reirieval sYSICmwitoom permi ion in iIInl-the publisher Ccmems of ads = ubjltd to
I s PJIO3L
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CIRCLE 114
1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
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_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
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CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
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CIRCLE 164
4 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgllllechnologycom 0 wwwpowerlmiddotfllllsmssoncom
EDITORIALPublisher amp Edltor-iu-Chief
Michael Goldstein
Managing Editor William R SIOlt
Associate Editor Joseph L Hazelton
Editorial Consultant Paul R Goldstein
Technical EditorRobert Errichello
DOli McVitticRobert E SmithDan Thurman
ARTArt Director lean Bartz
ADVERTISINGAdvertising Manager Patricia Flam
Advertising Coordinator Gladyce J Cooper
CIRCULATIIONCireuladon Coordinator Dina Krauss
INTERNETWeb Developer Dan MacKenzie
Gear Industry Home Pagelgt SalesPatricia FlamDavid Tornalis
RANDAU PUBLlSHlliNG STAfFPresident Michael Goldstein
Vice President Richard GoldsteinControUer Michael Grafman
Accounting Dianne Johnson
Phone 847-437-6604EmailmiddotpeoplegeartecJanologycom
Web wwwgeartechnology comwwwpowertransmisrioncom
VOL 19 NO 1GEAR TECILlOLOGY The Jour of GtarManuracturing (ISSN 0143~685S) is published bimonth-[1 b~ RomWl Publishing lnc 1425 Lam Avenu e PDBo 1426 EIk Gro Village IL 60001 (841) 43](604Cltt ve r price S500 US Periodical postage pmd trtin HeIghtlt 11 altlltlat odltIilioooI mallin~ m~Randall Publishing makes every effort to ensure ht theprocessev described in GEAR TECHNOLOGY conform10 sound engineering practice Neither Ihe au~ho~ nor thepublisher can be held responsible fer injuries iiultta3nedwhlle faUn-wing the procedures dascribed PostmasterSend uddress changes [0 GEAR JECHNOLOGY TheJournal of Gear Manufacturing 1425 Lunt Aven e PO130 1416 Elk Gmv ViILgoL 60007 OCQntefl copyrighted hy RANDALL PUBLISHING INC bull 2002 Nopm of Lhi publicelon may be reproduced or eensmtuedill any forrn or by Wly means eieeuente or mecbarucaJmduding phoeocupying recording or by any mformllllon
nd reirieval sYSICmwitoom permi ion in iIInl-the publisher Ccmems of ads = ubjltd to
I s PJIO3L
Quieter GearsEngineered Metals
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Dura-Bar conttauous-cast gray and ductileiron performs like free-machining steel with animportant addedbonus - quteter operation
Uke steel Dura-Bar can beaustemperedthrough-hardened flame-hardeaed or induction-hardened for added wear resistance But thesuperior noise and vibration damping eharacteristiesofDura-Bar make for quieter runninggears And Dura-Bar Is 10 lighter than steel
Dura-Bar round bars are available In diametersranging from 58 to 20 and lengths of 6middot20 So youwont need to make major changes in your machining equfpmentAnd our extensive Inventory means Dura-Bar is available nQW - when you need it
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CIRCLE 158
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CIRCLE 114
1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
TSUBAKIMOTIlCHAilN CO
RENDER CORP
cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
When big th-ngs are onthe mov
fasslerCorporation131W Layton Avenue Suite 308Milwaukee WI 53207Phone (414) 769-0072Fax (414) 769-8610E-mail fasslerexecpccom
internall spllnes
bull wwwfaessller-agchCIRClE 119
The Gear Technology Buyers Guide 2002
COPIES STILL AVAILABLEThe Complete Geilr Industry on CD-ROM
bull Machines bull Cutting Toolsbull Services Gear Manufacture rs
bull Gea r Drive Manuf eturers
Everything you need to make or buy gea rsGet your eXIra copy today
FAX THIS FORM TO (847) 437middot6618OR MAIL TO PO BOX 1426 EUC GROVE VILLAGE It 001109 USA
$95 each while supplies lastDYES I would Ilke to receive the Gaar Tachncloqv Buyers Guide 2002
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
Provides vital SPCinformation
9 I QD 8ID
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CIRCLE 12310 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnoogycom bull wwwpowertransmfssloncom
IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
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wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
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CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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GEAR TOOTIH GRINIDllNGiSpur Iielical
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
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Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
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lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
TSUBAKIMOTIlCHAilN CO
RENDER CORP
cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
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American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
When big th-ngs are onthe mov
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internall spllnes
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The Gear Technology Buyers Guide 2002
COPIES STILL AVAILABLEThe Complete Geilr Industry on CD-ROM
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
Provides vital SPCinformation
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
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If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
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IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
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IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
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Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Brief HistoryGear NomenclatureDrawing Data Requirements
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1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
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All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
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Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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f h h
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
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CIRCLE 114
1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
TSUBAKIMOTIlCHAilN CO
RENDER CORP
cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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1II_------- -IIPUBUSiHERS IPAGiE
replaced altogether
Cyber-SeminarsA Virtual Success
yen-ou hardly have to leave your office anymore because
the whole world L being piped right to ymu desktop E- know because I recently attended my first seminar by
Internet
The seminar sponsored by the American Gear
Manufacturers A sociation w called The Economy and theGear Market What Come Next]t wa presented by Dr Mike
Bradley prnfes or of economics at George Wa hingtonUniversity in Wa hington DC Dr Bradley presented slidesover the Internet while he poke to participant via telephone
Dr Bradley presentation a always was both interesrmgand informative He the economics professor everyone wishehe had in college Not only is Dr Bradley well informed 800m
the gear industry bUI aliso hes able 10 explain economi s insimple easy-to-understand language
Regrettably there werent a lot of positive thing for Dr
Bradleyto say in the middle of a ma~ufacturing recession BUI
the pre entation gave usa better idea of whats been happeningand what to e pecl in the coming month
Of course the que middottion everyone wants answered-whenwill the mannfa luring recession be over--callt be predictedwuh any certainly However history has provided some meas-ure of as urance in this area According to Dr Bradley the aver-age reee sian since World War IIIhas lasted around 11 monthsAllhough some have lasted considerably longer were alreadymore than a year in~o this manufacturing recession so hopeful-ly we dont have to wait much longer for recovery
While I wasnt terribly encouraged by Dr Bradleys near-term expectations I was certainly encouraged by the format andtechnology of (he seminarjtself Dr Bradleys lides appearedon our computer screen and he controlled them from hi loca-tion flipping through them just as he would in a lecture hall Hewas even able 10 highlighl and animate portions of the presen-tati n as he spoke
AI 0 participants were able to ask que lions either by typ-ing them into their brow ers or al certain points during thepresentation by speaking them over the phone lines The
phoned-in questions could be heard by all the other participantJUI as if tJiley were sitling al a traditional conference
As a whole I was very impre sed at how the technology pro-vided an experience nearly duplicating that ofa live seminar
This is not 10 aylhat the format does not have irs draw-backs Irs 110t the same as being there ill person Much of theInteraction hal rakes place ill person cant happen in a virtualselling Often a conferences its the communication that rakesplace in the hallway or the hotel lobby that proves the mostvaluable The value of (hat face-to-face contact cant be
wwpowllrlrnmluioncom I7r1I11010171om bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002
However one of the main advantages of the Internet tele-coafcrence is its ability to expand the potential audienceAccording to Joe FranJdin AGMAs executive director 42 com-
pany locations participated in the event The average number ofindividuals at each location was 49 resulting in more than 200total attendees AI a typi al AGMA markeung comrmuee meet-
ing somewhere between 50 and 75 people normally auendFranklin says
AI most technical seminars just one or two people from any
company are able 10 attend But with a virtual seminar hereno airfare or accommodati ns to worry about so the price ofattending goes way down Plus the only time lost at the office
is the lime for the seminar itselfIncrea ing the availability of technical information was one
of the founding principles of this magazine About 18 years agowhen I founded Gear Tech1lulogy many gear-related technicalpapers were being pre en led atconferences around the worldbut most of the gear manufacturing eomrnunity never saw the
papers The fact that a much larger audience is interested in (hatinformation is one of the reasons for this magazines success
The virtual meeting technology has similar potential We1soon see this format used for more comprehensive events suchas AGMAs many technical committee meetings or any numberof other seminars and presentations held by other organizations
According to Franklin the AGMA plans to make good useof the technology over the next year l believe hat 3I1ything that
pread of infonnalion-espe-dally information that ofvalue I[Q our indu lry-icemmendable
So [ congratulate the
AGMA for their efforts inthi endea or and [ look
forward to future use ofthis and similar technolo-gies
YOUR
BROWNINGEMERSONPOWER TRANSMISSION
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RENDER CORP
cmCllE 17118 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgesrlechnoIOllycom bull powerrnsmrS$J(fI com
_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
TRY lOUR RAPID READER RESPONSE SYSJEMIGOlIa wwwgeartechnologrcommllrmIDrequestadditionamiddotllinformation from any IdVIlrtiserin this iuue VourfequHt will be SlInt 101thll adver-liser with in 24 hOIlJl forsuper-fast tumanlund
I Formorelinformation about I product or service advllrtised in this issua of Gear fecfmgy cirele the appropria1Jlnumber on the Rllder Relpollsa Cardand put the card in thlllmail
READER PAGEI
READER PAGfADVERTISER SfRVlGE NUMBER NUMBER ADV1RTlSER SERVICE NUMBER NUMJI~RAero Ge3J IRC 127 43 K1SSsofi 136 46
American Metall Treating Co 181 47 Koepfer America LLC 137 47Applied Process Inc 131 46 Koro Sharpening Service 163 41Arrow Gear Co 166 4 Kreiter Geartech 141 47Bourn amp Koch Machine Tool Co 156 40 LeCounllnc 164 ltI
Dr Kaiser (S L Munson) 116 41 Mjdwest Gear amp Tool toe 168 40Dragon Precision Teols Co Ltd Midwest Gear Corp 154 47
(Ore Allen 0) 149 12 Nachi Machining Technology Co 114 6Dura-Bar 158 5 Okamoto Machinery 153 47Eoplas Inc 152 13 Perry Technology Corp 134 meFllsslcr Corp 119 9 powertransmissioncom 171 8TM Gear lnduslry Home PageTW 22 Proce ss Equipfrleo Co 122 45
Gear Technology Center Div The PlLrdy COIp 110 3lt1of Mitsubisbi International CDIp 175 24-25 Randall Publishlng Int 328 36
Gleason Corp 162 46 Raycar Gear amp Machine Co 180 46Gleason CULtingTools Corp 105 141 160 14746 Sfar CUer Co 100142 247The Gleason Work 110 I SU America [nco 107 BCInsco Corp I 39 I TSA Transrnecanica (Greg Allen Co) 172 43Imerstaee Tool Corp 151 47 II United Tool Supply 123 10ITW Htartland 124 39 University of Wisconsin--Milwllukee 130 33
When big th-ngs are onthe mov
fasslerCorporation131W Layton Avenue Suite 308Milwaukee WI 53207Phone (414) 769-0072Fax (414) 769-8610E-mail fasslerexecpccom
internall spllnes
bull wwwfaessller-agchCIRClE 119
The Gear Technology Buyers Guide 2002
COPIES STILL AVAILABLEThe Complete Geilr Industry on CD-ROM
bull Machines bull Cutting Toolsbull Services Gear Manufacture rs
bull Gea r Drive Manuf eturers
Everything you need to make or buy gea rsGet your eXIra copy today
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
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wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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CIRCLE 136
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CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
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I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
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bull Wormlbull SpurI Helical
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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f h h
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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_______ BOOKREVlEW _
The IGearAnalvsis Handbook bV Jemes L lav1lorVibrallion IConsuUants Illne
IReviewed by Robed E Smith
The author has written this bookpri-
marily from the viewpoint of analyzingvibrations on heavy industrial and mill
geariag that may have been in service fora prolonged time The purpose is to diag-
nose problems especially the source or
eau e of failure However the principles
and analy is technique can be used forall types and sizes of gear as well as forgear noise analysis
Gears are of complex geometry and
there are many possible ources of prob-
lems including the rnountiag or assem-bly (housing) The author has done a
very thorough job of describing the tech-niques of analyzing vibration signalsboth in the time domain as well as thefrequency domain (FFT) He has tres edthe importance of looking at time-basedsignals Many times engineers look atonly the frequency pectrum and wiHmis orne very important data or the fact
that something about the gears has dis-
torted the spectrum or made the data use-less such as nicks and burrs OF over-
loaded signalsThere are many bits of information in
iii gear vibration or noise spectrum
be ide just me h frequency The authorhas been very thorough in describing the
causes of unu ual peaks in a spectrum(other than meshfrequency and harmon-ics of mesh) These are uch things as ]2and 1-12 harmonic of mesh which
occur quite oftenSome other unusual peaks are ghost
harmonics In the gear trade these ltwepeaks caused by undulations whlch
are iii unique form of waviness on thegear teeth cau ed by kinematic errors inthe gear train of the machine that pro-
duced the gear teeth The culprit is usu-ally the final drive gear mounted direct-lyon the workspindle There has to be aninteger number of waves around theproduct gear which is equal to the Dum-
The Gear Analysis Handbenk ISBN Omiddot9640517middot1middot0 was published ill 2000 byVwralioll ConsultDnt Inc The 256-page1)001 co~s $10995 plus shipping I~ CQI beordered through Vibration Consuiumtslncby calling (813) 839middot2826 by sending e-mailmessages 10 ilruovibconscom or by visit-ing wwwvlbcons()omber of teeth on the workspindle drivegear Ohost harmonics are the type ofthing that submarine have looked for inthe analy is of onar data They wereused to identify hips and tile machinesthat produced the marine drive gears onthe ships Current AGMA and ~SO stan-dards on gear tooth surface finish and
texture describe this ghost harmonicsphenomenon
Chapter 10 is a good place for anyIedmician or engineer to tart whenthinking about making vilbration or noisemeasurements of gears or a gearbox Therest ofthe book goes a long way to guide
the person in methods and techniques ofgelling the most information out of the
analysis 0Circle 304
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please fax your response to theattention of Randy Stott managing editor at841-431-661 B
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
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cornpanieindustry
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Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
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Tell Us Whit YouThink
If you found this column of interestandor useful please circle 3IIZIIyou did not care lor this columncircle303
po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
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the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
Home Page httpvVWwpurdytransmissonscomE-Mail salesputdytransmissionscom
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
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This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
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IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
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IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
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Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Brief HistoryGear NomenclatureDrawing Data Requirements
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1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
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All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
PreciseProfiles
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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CIRCLE 107
The Gear Technology Buyers Guide 2002
COPIES STILL AVAILABLEThe Complete Geilr Industry on CD-ROM
bull Machines bull Cutting Toolsbull Services Gear Manufacture rs
bull Gea r Drive Manuf eturers
Everything you need to make or buy gea rsGet your eXIra copy today
FAX THIS FORM TO (847) 437middot6618OR MAIL TO PO BOX 1426 EUC GROVE VILLAGE It 001109 USA
$95 each while supplies lastDYES I would Ilke to receive the Gaar Tachncloqv Buyers Guide 2002
Number of copies _ X$95= _____ total
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Provides actual overball pin measurmentof any helical or spurgear or spline withoutthe need of costlysetting masters
Provides vital SPCinformation
9 I QD 8ID
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CIRCLE 12310 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnoogycom bull wwwpowertransmfssloncom
IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
Tell Us Whit YouThink
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po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
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SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
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CIRCLE 107
IREVOLUTIONS _
IGordonNew Wins IGear CIock 1 bull George T Shturtz Metal Powder
Gordon New managing director of i Products Co and Ioperations for Ron on Gears of Au - bull Paul Wandler LampH Welding amp I
lralia was Ihe grand prize willllcr in II Machine CoGear Technology drawing held in Congratulations to all of the winners
October at Gear Expo 20lH in Detroit land thank you to all who came 10 Gear IINew won a one-of-a-kind gear clock II Expo and visited us Those who are inter- Isculpture cu tom made forthe event ested in a marketing consultation but
The cirawing was pan of Gear I who didnt have the chance 10 come to Technologys booth promotion at Gear I (he show can call u at (847) 437-6604 ]1
Expo The emphasis of the booth was CUrle 300 bullMarKeting in the Gear Industry I
Individuals had the opportunity to COD- Iisult with OUF staff about the adverti ing
1and promotional opponunnie availableto companie in Ihegear indu try 01
cornpanieindustry
Visitor to the booth entered the con-
wan Ling 10 reach the gear
test by dropping their business cards in abox The drawing wa held Tuesday
Ocrober9[0 addition to the custom-made origi-
nal clock Tile Gear IlIduslry HomePagetrade and powertrcmsl1IissiollcomTM
held drawings for smaller worm-and-wheel clocks The winners of jhosedl1lwing were
bull John R Arbisi Ingersoll ContractManufacturing Cobull Gerard 1 Connell Cloyes Gear ampProducts Incbull Jeff Coursey Nacbi Machining
Jechnoogy 0
Alexander J Gunow Midwe I
Thermal- Vac
Theparts inlemal gears with smalldiameter and heat-treat distortion Theproblem how to grind the distortion
from the teeth A solution grind bybroaching
HI sler AG has a modified broachingproce thai provides the surface rough-ne of ground gears where grinding isnt
possible because of space problems likein internal gears with small diameters
The process lise a diamond-coatedshort broach and multiple up-and-down
strokes to remove heat-treat distortionf-rom broached hardened workpieces
Located in Dubendorf SwitzerlandFassler has offered the process since toe
mid-l990 While not new the diamond-coaled hort broach appear unique as a
fini hlng tool for internal gearsAccording to Martin Gerber [l Fassler
alesrnan only his company make ucha broach The broach operates in the
IGOnlOD New o~R1111son Ge-nll IIml]l and Gear TilchlJoio9YIIlublisher MichaellGollfsteln hoIdlh_ g811JdoclIlhll Naw WOnin lh Gear Technology siwing II Gill amp110 200~
Welcome UJI Revolutions the col-umn that brings you the latestmost up-Io-dale lind easy-ro-readinfomation about the peopland technology of the geaindust-y Revoiliutions w91comesyour submissions Pease sendthem to Gear Technology POBox 1426 file GIoe Village It60009 fax B47)431-6618 Of e-mailpeoplegeartechnologycom
youd lilee more information aboutany of the 8niclBS thaI appBarplease circle the appropriate nummiddotber onthe Reader Response Card
companys Hmiddot -100 hard broachingmachine
Biilent Yesilalp ii slers ale direc-tor describes the short broach proces asimple and reliable and as a lowcostsolution for high volume production
In this process the illiemal gear lieson the broaching machines deposit tableand is held in place by a hold-down barThe gear isnt rigidlyclamped 0 the
broach can move it according to tilegears cemen
With a mounting flange the shortbroach has a centering zone to positionthe gear Wilh the profi le and check the
allowable Unollta tapered zone 10
remove stock and a ground cylindricalzone to calibrate or flatten the profile
In a normal broaching machine driv-en by a hydraulic cylinder the broach ispulled down through a gear blank in onestroke
In the HS-IOO the broach is pu hed
up and pulled down through an internalgear opening Wh lithe broach exits up
or down chips are rinsed from betweenthe broach and gear by the deposittab les ring nozzle Designed to finishgears the broa h can remove only 25-40microns of stock
Jso the short broach process avoida problem with the long broachprecess
wltpoweTlrnrmluloncommiddot WWWgerrechnolo ycom bull GEAR TECHNOLOGYmiddot JANUARVFEBRUARV 20Q2 11
-- REVOLUTIOiNS __ ---- bull
elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
Circle 30l
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This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
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To request more infomation on this product pla e COR-
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l~onhmwgeaFcom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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CIRCLE 147
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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elastic deformationFassler has produced diamond-coated
long broaches for more than 20 years
Such long broaches could be made forfinilting internal gears BUI lite broachssingle long stroke expands its work-pieces which later brink
The short broach process uses multi-ple short strokes so elastic deformationin a gear from one stroke can shrink and
be removed during tile next strokeWe have no expan ion in tile work-
piece Gerber says That was the rea-son to change to this short broachprocess
Thus the short broach grinds heat-
treat distortion from internal gears giv-ing them their properprofile within their
tolerance range The broach providessuch accuracy whether its new or old
FissIer IGorp multiple-moke short broacheslike thIs onll nUl finIshmiddotbroach internal gellrswith small diameters and heat-treat distolli en AlIears major d iamlll8F can b as smalll -1201 mm
When new the broachs dimensions
are their large t 0 its finished gear willihave dimen ion at the lower smallerend of their tolerance range
As (he broach is used its diamondgrit will wear away The broachs dimen-sions will become smaller so its gearsdimensions will move toward the upperlarger end of their tolerance range
When the broach is mallest in sizeand needs to be replated gear dimen-sions will be at the upper end oftheir tol-erance range The change in the broachssize is the tolerance range of its internal-gear workpiece
The workpieces dimensions canrange from 30-250 mm for its outsidediameter 20-80 mm for its internal-gear
diameter 3-100 mm for its heighl and3-55 mm for its gear-profile height
Each diamond-coaled short broachha a lifetime of 200-300 meters ofbroaching length and a cycle ti me of
I
A short hrcaeh slicks out of the HS-100 deposittable and ringl nozzle below lhal machine toolshold-down bar Tile broacb uses muiliplll up-Dlld-dOWIIstrokes to provide lmernal gealrSwitbtha sulfaee roughness llf ground gears
12 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY gsllfschnologycQm bull pO -rtrensmtsstoncom
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CIRCLE 1491
RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
each broach canfini h-broaeh the flankand major diameter of 10000-15000gears Al 0 each gear wouM have a cyetetime of 30 seconds and cost about 30cents to finish The 30 cents per gearincludes the cost of replating the broachduring its lifetime Each new broach co Is$6000- 15000 depending on its ize
The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
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po rrrlllmiulollCom wwlIsrlsCitloIOllycom bull GEA TECHNOLOGY JANUARYFE8RUARY 2002 13CIRCLE 1112
This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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RrVDLUTIDNS ------------II1II
The Ishon Ibroach eenters a gea r with its lupperset ID~teetb haD removes SlJlcl aDd fJIItt1RS hIars prome with Ibe lower sellof teetb
20-40 econd to finish an Internal gearA liming a gear height of 20 mm
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The broach lifetime is defined by it troke length The Ienger the troke thegreater Ihe stre on the broachs dia-mond coating and the honer thebroachs lifetime That lifetime alse canbe shortened by work parameters set byhe machine operator
At il smallest ize the broach musthave its coating removed then be replat-ed and reground with anew coaling 0]
metallically attached industrial-diamondgrit The broach can be replatcd threelimes before it rnu t be discardedReplatillg can be done by companiesother than Eissler
Beside removing heat-treat disror-lion the broach removes an internal I
gears helix pitch and taper error I
Gerber and Yesilalp add that the broachincrea es the gear contn I ratio withlower peak tre e and lengthen thgears lifetime
According to Ye ilalp the hortbroach proce scan implify a semblyofgears and shafts He explains that the
proee s create gears with correct dimen-sions-s-gears dont even need to berueasured=-so gears and shafts donthave to be built in pairs
He add that the proce s can reduceheat treatment costs for some applica-tions by eliminating over-pinion heallreatment
And Fasslers hort broach processisnt Iimitedtoiruemal gear hapes The
proce 31 0 can fini h-broaeh ingle andmultiple keyways polygons and otherpiine profiles
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This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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This paper waspresented at ~he8thInternational Power
Transmission andGearing Conference
Baltimore MItSeptember 200011was
later published in theJaume of MechanicalDesign~March 2001 bV
the American Society ofMechanicall Engineers
David G Lewickiis a senior aerospace engi-
neer witt tile US_ArmyResearch Laboratory atNASI s Gleim Research
Center ill Cleveland OH_He has been involved ingear crack propagmion
research as well as trans-mission life and reliability
predictions ami geardynamics predictions Healso has worked orl low-
noise high-strength spiralbevel gears face gears for
helicopter drive systemslubricants and diagnostics
He lias written or eo-writ-tellmore than 70 technical
article in the field ofdrive systems
lisa IESpieV8kis a structural engineer ill
the design and analysisgroup of ATA EngineeringInc located ill San Diego
CA Sire is 011 expert inopplying computer tech-
niques to design analyzeand test highly stressed
structures and In interpret-ingfracture and fatigue
requirements for thoseslllcrure~middot As a graduate
student she performedresearch with the CornellFracture Group ill which
she simulated three-dimensionalfatigue crack
growth in spiralbevel gears
Consideration of Moving ToothLoad in Gear Crack
Propagation PredictionsDavid Glewicki llsa E Spievak PaullA Wawrzynek
An1hony RIingraffea and Robert FHandschuh
IntroductionEffective gear designs balance strength dura-
bility reliability size weight and cost Even
effective designs however can have the possibil-ity of gear cracks due to fatigue In addition truly
robust de igns consider not only crack initiationbut also crack propagation trajectories As anexample crack trajectories that propagate
through the gear tooth are the preferred mode of
failure compared to propagation through the gearrim Rim failures will lead to catastrophic eventsand should be avoided Analysis tools that predict
Figure I-Location of loadeases for finite elemenmesh
crack propagation paths can be a valuable aid 10
the designer to prevent such catastrophic failures
Pertaining to crack analy is linear elastic frac-ture mechanics applied to gear teeth has become
increasingly popular The stress intensity factorsare the key parameters to estimate the characteris-tics of a crack Analytical method using weight-function techniques to estimate gear tooth stress
intensity factors have been developed (Refs I and17) Numerical techniques such as the boundaryelement method and finite element method have
also been studied (Refs 12 and 21 ) Based onstre s intensity factors fatigue crack growth andgear life predictions have been investigated (Refs
2 3 5 and 9) In addition gear crack trajectorypredictions have been addressed in a few studies(Refs 6 7 13 14 and 19)
From publications on gear crack trajectory pre-dictions the analytical methods have been numer-
ical (finite element method or boundary elementmethod) while solving a static stress problem In
actual gear applications however the load movesalong the moth changing in both magnitude and
position No work has been done investigating theeffect of this moving load on crack trajectories
The objective of the current work is to studythe effect of moving gear tooth load on crackpropagation predictions Iwo-dimensional analy-sis of an involute spur gear using the finite ele-ment method is discussed Also three-dimen ion-
al analysis of a spiral-bevel pinion gear using theboundary element method is discu ed A quasi-static numerical simulation method is presented inwhich the gear tooth engagement is broken downinto multiple load steps with each step analyzed
separately Methods to analyze the steps are dis-cussed and predicted crack shapes are comparedto experimental results
Two-Dimensional AnalysisGear ModeUng The two-dimensional analysis
was performed using the FRANC (FRactureANalysis Code) computer program developed by
a) load on tooth 12
K~6 5 4 3 2 1
~K
35
14 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgearI9chnologycom wwwpowertrensmtseioncom
-1
-2 L-_---_--_L_-L_~_--L----
2520
f~ 15
sect ~ 1~
j 0-ltn -5 --------------------
0) Load on looIJi 3 01D---O------o-- K
i E 1 18 17 16 15 14 13 is
11
~l 0 ll I 1sect 1sect H 13~ ~~
I ~ _ ~~J --_L_---L_J_--J
o 5 10
j 2
15 20 25
Figure 2-Mode I and mode 11stress intensity fac-lorsol awlit wad alld an initial crack oj 026 mm
Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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Wawrzynek (Ref 23) The program is a general-purpose finite element code for the static analysiraquoof two-dimensional cracked structures The pro-gram uses principles of linear elastic fracture
mechanics and is capable of analyzing planestrain plane stress or wej-symmetric problems Aunique feature of the program i the ability to
model crack and crack propagation in a true-ture A 10 ene of quarter-pciat ix-aode triangu-
lar elements is used around the crack tip to model
the inverse square-root stress singularity Mode Iand mode [J tre inten ity factors K1and Kifrespectively can be calculated u ing a variety ofmethods (Asa refresher mode m loading refers to
loads applied nonaal to the crack plane and lendsto open the crack Mode WIrefers to in-planeshear loading) The stres intensity factors quan-
tify the tate of tre in the region near the cracktip In the program the tre inten ily faCIOcan be used to predict the crack propagation tra-jectory angle again using II variety of methods
In addition the program has a uniqaere-meshingcherne to allow automated proces ing of the
crack imulationA spur gear from a fatigue test apparatus was
modeled to demon trate the two-dimensionalanaly i The modeled gear had 28 teeth II 200
pre sure angle II module of 3 175 mm diametral
pitch of 8tin) and a face width of635 mm (025in )The gear had a backup ratio (defined a the
rim thickness divided by the Iooth height) of 33The complete gear was modeled using mostly 8-node plane sires quadrilateral finite dements
For improved accuracy the mesh was refined onone of the teeth in which a crack was inserted
The total mode] had 2353 elements and 7295nodes Four hub nodes at the gear inner diameterwere fixed to ground for boundarycoedirionsThe material used was steel
lootll Loading Scheme To determine theeffect of gear tooth movlng load on crack propa-gation the anaJy is was broken downinto 18 sep-
arate load case (fig 0 An initial crack of 026mm (0010 in) ill length was placed ~n the filletohooth 2 oormal [0 the surface at the location ofthe maximum tensile tres (uncracked condi-tion) Six load cases were analyzed eparatelywith the load on the tooth ahead of the crackedtoojh six 011 lhe cracked tooth and six on thetooth after the cracked tooth The calculatedstressintellsity factors for unit load at each of theload position are hewn in Figure 2 TheseStress intensity factors were calculated u ing theJ-integraJ technique (Ref 20) Load on tooth 2(crackedtooth) produced ten ion at the crack tip
20 _load on looln 2
- lOld on tOOlgt J~I I
Load on toolh 1-I I
fII
40Gear rotation degreea
50
PaulAWawrzynekis a senior research associ-(Iff in 11( CompulaliOlwlMlIIlrials tnstitute til
Cornell Ulillrsil)s TheoryCenter and ill Ih CornellFracture Group A civitengineer he has focusedhis research primarily ondewoping ~oftwareforsimulaing crack gro th in11 range ojllgintlringstructure sand marerialsAbo Ire managelaquo FractureAaIJ~isConsultunrs Incwhich provides crackgrowth analysis and soft-waTldevelopmen servicesfor differeru industries
Anthony RlngraHeslis u pro[r Jar 01 1M Schoolof Cilmiddotjf and poundrwirollmenlaiEligilleering tu CornellUniversity Ioctued inIthaca NY A civil engineerIrlflraffla focuses hisTISI(lrcI 011computer simu-
lution (wd physical testing(Jf complex fracturingproclSSls He and his stu-
dents have performedresearch in usiII interac-tive computer graphics incampillaliona fra(uremechanics Wilh Iris 51u-
dents he has written mort(han l80 papers 011 com-plex jracwrinp proc-essesand compuuutonat fracturemechanics
IRobert F Handschuhis llll (I rospaclaquo engineerl1ilh the Us Arm)Reuarch Laboratory atNASAr Glenn Res arrhCemer Hi research hasconcentrated on powertransmission his researcbin gtoring has focused onI_tperimental and anaiyticalstudies of spiral bevel fact bulland lIighlptld gearing Hthas lOriCltl1 or co-writtenmort than 65 reports in tMfields [ seal gro lindrrUlllEricaJ methods
www-powltflransmlufoncom QltarltchnQcom bull GEAR TECHNOLOGY bull JANUAIRYfFEBRllAFY 2002 15
Figure 3---DANST computer program 0utpuJ 0stalic geal toolllload 68 N-m driller torqueK increased as the load moved toward the toothtip (load cases 12 to 7 Fig 2b) due to thincrea eel load lever ann Lo ds on tooth 3 alsoproduced ten ion aI the era k lip bUI at an orderof magnitude le than those produced from theload on tooth 2 (Fig 2c) Loads on toota I gavecom pres ion to the crack lip as shown by the neg-ative K values (Fig 2a)
Next the actual load magnitudes on the geartooth were considered as il wenl through thmesh The computer program DANST (Dynamic
ANaly is of SPIll gear Tram mission Ref 15)was used for the analysis 1bi program is based
on a four-degree-of-freedom torsional lumpedrna model of n gear tran mi sian The modelincludes driving and driven gears connecting
shafts a motor and a load The equations of
motion for this model were derived from basicgear geometry elementary vibration principlesand time-varyingtooth stiffaesses For simplicitythe static gear tooth loads of the solution weredetermined ( ig 3) TIle e loads were deter-mined from well-established gear tooth stiffne
principle and static equilibrium The loads arehewn as a function of gear rotation for adriver
torque of 68 N-m (599 in-lb) Tooth 2 began
contact at a gear rotation of 100bull As the gear rota-
tion increased the load on tooth 2 graduallyincrea ed Tooth l and tooth 2 shared the load fora rotation from Hlo to 180
bull From l8deg to 23deg tooth
2 carried the complete load At 23deg tooth 2 iscan idered at it bighe Ipoint of single tooth con-tact (HPSTC)
The stre s iDlenity factors as a function ofgeU rotation were then determiaed by multipjy-
ing the stressimensity factors determined fromthe units loads (Fig 2) by the acreal looth loads(Fig 3) and applying superposition since linearelastic fracture mechanics was U ed The rr-eultsare shown in Figure 4 As expected the mode Estress intensity factor (Flig 4a) was mostly influ-enced by the load on tooth 2 Note that the largestvalue of Kl eceurredat the HPSTC AI a note that
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
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SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
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CIRCLE 107
HlAI__Hj~pound j~
i 15
10~ es c
~ 00Zl -05iiij
-1010
Figrjre 4--Slress ilJlellsity and tangential stressfactors as afuncrion of gear rotation 68 N-mdriver torque 026 mm inilia crack size
238 crac bullbull __h mm10 a) Mode I stress in1ensi1y factors 158 - ~
079026
b) Mode II stress Intensity ractors
o 10 20 30 40 50
Figure 5--Stress inlensity factors from gear tooth crack propagatitm simukraquotion backup ratio 33
30 a) Mode I stress inli3flslty faclars
~L- __ ~ __ ~~ __ ~ __ ~~ __ ~ __ ~
e bl Mode II stress inIensItyfactorsCracI length mm
158079026
6
4
2
0
middot2middot10 0
Figure 6-SlTess intensity factors from gear toothCTtld propagaJion simula-tiOTl backup ratio = O~2
10 20 ao 40 50Gear rolaJIOll clegrees
11 the magnitude of K (Fig 43) was much largerthan that of Kl (Fig 41raquo This implied thai K wasthe driving force in the crackpropagation KIf
however affected the crack propagation angle aswill be shown in the next section
Crack Propagatiofl Silllulatioramp FromWilliams (Ref 24) the tangential stress near acrack tip G9B is given by
where rand (are polar coordinate with the ori-gin at the crack tip Erdogan and Sih (Ref 8) po -tulated that crack extension starts at the crack lipandgrows in the direction of the greate t tangen-tial sire s The direction of the greatest taagendalstress is determined by taking the derivative ofEquation I with respect to B setting the expres-sion equal to zero and solving lor (Performingthe math this predicted crack propagation angle8m is given by
9= 2 tan
rom Equation 2 the predicted crack pmpaga-tion angle is a function of the ratio of K to Kit
Erdogan and Sih (Ref 8) used brittle ptexiglassplates under static loading to validate their pro-posed theorems (iethe ratio of K to KII was con-stant) For the gear problem in the currern rudyhowever the ratio of K [Q KII was not constant dur-ing gear rotation This is hewn in Hgure 4c (actu-ally plotted as the ratio Kil to K for clarity) lnaddi-tion Figure 4d gives the calculated B fromEquation 2 as a function of gear rotation
In order to simulate gear crack propagation amodification to tile Brdogan and Sjh theory waspostulared in the current study This modified the-ory slate that the crack extension starts at thecrack tip and grows in the direction of the great-est tangentiol tre s as seen during engagement ofthe gear teeth The procedure to calculate thecrack direction is as followsI) K3Ild Kllare determined as 3 fullction of gearrotation (Figs 4a and 4b as described ia jhe pre-viees section)2) the ratio of K to KI as a function of gear 1100a-
tion is determined (Fig 4c)3) 8m (using Eq 2) as a function of gear rotauonis determined (Fig 4(1)
4) (100 (u ing Eq I) as a function of gear rotationis determined (Fig 4e)5) the predicted crack direction is the value of 9
16 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY bull bullbull chnologycom wwwpow ert ransmlssloflcom
for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
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WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
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l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
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at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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CIRCLE 153
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0 Statemiddotof-the-art CNCsharpeningand inspection machines
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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for which 000 i greate t during gear rotationFor the gear example given th tangential
stres fa tor (defined a 00 21rr) is plotted a afunction of gear rotation in Figure ltte Thi plot100 s very similar to the mode Lstre inten fly
factor plot (Fig 4a) ince KI was much largerthan Ku (see Eq I) The tangential tres waslargest al the HPSTC (gear rotation of 23) andthe predicted crack propagation angle at thi gearrotation was 9 43
sing thi propagation angle the crack wasextended by 026 mm (0010 in) re-me hed re-an_aJyzed and a new prepagation angle wa calcu-lated using the method de cribed above This pro-cedure was repeated a number of times to producea total crack lengjh of 238 mm (0094 in) TheO26-mm crack exten ion length wac based onprior experience in rderto produce a moothcrack path Figure 5 shows the stres intensityfactors versus gear rotation for a number of cracklength Note that the mode Lstres intensity fae-tors looked imilar but with increa ed magnitudeas the crack length itncreased In all case theselected crack propagation angle occurred whenthe tooth load was placed at me HPSTC Figure 6 hows a similar analysis bll1 with a model of athin-rimmed gear Here the gear was modeledbased 011 the previous design but wilIl lOIS incor-porated in the rim 10 imuiatea thin-rimmed gearThe backup ratio for thi model was 02 A eenthe magnitude of the mode I stres s inten ity fac-tors during len ion (gear rotations 18 10 45deg)were larger than that of the 33 backup ratio gearAlso there was a significant increase in the com-pre sive 1(1 (gear rotation le than 18deg) due to theinerea ed compliance of the thin rim gear
Comparison (6 Bxperiment Figure 7 howthe results of the allaty i compared to experimen-tal tests in a gear fatigue apparatus The originalmodel (backup ratio of 33) as de eribed beforewas compared along with model of backup ratioof 10 and 03 These later two models were creat-ed using lOIs in tile gear blank as previouslyde cribed The experiments were first reported byLewicki and Ballarini (Ref 13) Here notcheswere fabricated in the looth fiUet region to initiatetooth cracking of [est gears of various rimthicknes es The gears were run a 10000 rpm and at avariety of increasing loads unli] tooth or rim frac-ture occurred A en [rom the figure good cor-relation of the predicted crack Ifajectorie toexperimental re ults was achieved For backupratio Of 33 and 10 Looth fractures occurred Forthe backup ratio of 03 rim fmc lure occurred
As a final n te the llnal) i indicated thatthe
F~gureB-Boundary element modd of OR-58 spi-ral-bevel pinion
~-g 105l
~0
5
~OL1--~3~--~5--~7---79--~1~1--~13~~15-
b) Loads on tooth CQllIacI elhPles
Figure 9-location of tootl caatacellipses endmagnitudlaquo of load on OH~S8piralbevel piniontoothmaximum tangential tress at the crock tip alwayoccurred when the tooth load was positioned at theHPSTC Thus for two-dimensional analysi cra ksimulation ba ed all calculated stress intensity fac-torsand mixed mode erac angle prediction teea-ruques can use a Lmple static analysi in which thetooth load i located at the HPSl1 Thi was ba edon a modification to the Erdogan and Sih crackextension theory and the fact that the mode I tre sintensity factor was mu h larger than lhe mode WIfactor
Three-DimenionaJ Analy IGear Modelirlg The three-dirnen ional analy-
wwwpow6IrfrlIsmi$sloncom bull wwwgeaechn0ogyCOIT bull QEAR TECHNOLOGV bull JANUARVFEBRUARY 2002 11
1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CliRClE 144
GEARBurnishing rom Ihe SDurce
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Remove nicks burrs hear IffNJtscaleand Improve gear tooth sul1sce
0riIr 30 ~ar avo HtartIInI ~ Ihe gRf~ pIW8U 1111your InIIIID Ihe people wbltJ 1D181lloillhe p
~ FEAIWIElIIIICIJIIIEbull Fully culOma1ad OVSIemsbull High opeed machIneSbull Pot ed Gvltoc
odlaI1on SVIlbull AulltlmO1lt lPhtlriCci
po llonlngbull Tri oble dl designbull Hcxltono 01 vert 0
machIneSbull Variety at gea type
For addmanar tnlarmaltan on itiIlll~ andoT tluJctfOllgl QUI
lnnIK1IQlL 1I1s1 ourWBtmf8 ofwwwirwu~mm
IHeartiand120$ Jl(tI lV8I1W Wnt
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pawerlrllnsmlssoncom wwwgesrtchnoagycam GEAR TECHNOLOGY JANUARYFEBRUARY 2002 391
CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
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401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
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Stsr Eutter Co
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
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KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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1ront
100
Figure 1000tress intensity factors jrOmrlreedimenional OH-58 piniorl tootilcrack propagaJion simulaliOn step I crack area 596 mmmiddotz
20- a) MOde I stress inlens11y lICIors
15
o --3 - b) MOOe ll stress inlenslly IaeIors
Figure 11-5tres inten ily factors from 1Iree-tiime1JsiolU11 OH~S8 piniontoothfrackpropagation simulation step 1 normalized position alolC rarkfron~= 083
-2 - -L -- L- ----
000 025 050 075Normalized posbon along crack front
sis was performed using the FRANC3D(FRacture ANalysis Code for 3 Dimensions)computer program developed by Wawrzynek(Ref 23) This program uses boundary elementmodeling and principles of linear clastic fracturemechanics to ana1yze cracked suucurrcs Thegeometry of three-dimensional structures withnon-planar arbitrary shaped cracks can be mod-eled The modeling of a three-dimen ionalcracked tructure i performed through a series ofprogram Structure geometry grid point data areimported to a olid modeler program Here
I r appropriate curves and faces (or patches) are ere-I atcd from the grid data as well as a dosed-loop
surface geometry model This surface model ithen imported to the FRANC3D program forboundary element model preparation The usercan then mesh the geometry model u ing 3- or 6-node triangular surface elements or 4- or 8-nodequadrilateral elements Boundary conditions(applied traction and pre cribed displacement)are applied on the model geometry over faces
edges or point Initial crack such as ellipticalor penny shaped can be inserted in the tructureAfter complete formulation the model is hippedto a boundary element equation elver program Once the di placement and traction unknowns are
solved the results are exported back to theFRANC3D program for post-proce ingFracture analysis such as stre sinten ity factorcalculations can then be performed
The spiral-bevel pinion of the OH-58 heli-copter main rotor tran rnis ion wa modeled to
demon trate the three-dimen ional anal) is Thepinion had [9 teeth a 200 pre ure angle a 30mean pi ra IIangle a module of 366 rom (diame-tral pitch of 694in) and a [ace width of 3251mm (128 in) For OH-58 operation the pinionmate with a 7 l -tooth spiral-bevel gear operatesat 6(60 rpm and h a design torque of 350 N-m(3099 in-lb )
The boundary element model of the oH-58pinion developed by Spievak (Ref 22) was 11 edfor the study Three teeth tbe rim cone and thbearing uppert shafts were modeled (Fig 8)The tooth surface and fillet coordinates weredetermined from the method developed byHandschuh and Litvin (Ref ] 1) and Litvin andZhang (Ref 16) The melt of the three teem warefined for improved accuracy A ha1f-eUip ini-tial crack with major and minor diameter of3175 mm and 2540 mm respectively (0125 inand 0100 in) wa placed in the fillet of the mid-dle tooth normal to the urface The crack wascentered along the face width and centered along
1middot8 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY g99rlechlloOllycom bull w po ltfrnmlnoncom
11 b) Mode II stress inensiIy I~
o
-1 ~--~--~----~--~----~--~--~1 3 5 13 157 111
Load case
IIIIWIWpowflfrnsmJssloncom wwwlI srt chn0ogycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 19
the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
Home Page httpvVWwpurdytransmissonscomE-Mail salesputdytransmissionscom
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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the fillet The complete gear model had a total ofabout 2600 linear elements (both triangular andquadrilateral) andabout 2240 node For bound-ary conditions the end nodes of thelarger-diarn-eter haft were fixedand Ille node on the outer
diameter of the smaller-diameter shaft were con-strained in the radial directions Again the mate-
rial was steelTooth Contact Analysis and Loading
Scheme Due to the geometrical complexities andthree-dimensional action numerical methods arerequired to determine the contact loads and posi-tions on spiral-bevel teeth since no closed-formsolution exists The method of Litvin and Zhang
(Ref 16) was used to determine the mean contact
points on tile piral-bevel pinion tooth Themethod modeled tooth generation and tooth con-tact simulation of the pinion and gear With themean contact points taken a the centers contact
ellipses were determined u ing Hertzian theory(Ref 10) Figure 9 shows the estimated contacteflipses on the spiral-bevel pinion tooth Fifteenseparate ellipses (load cases) were de lenni nedtarting from the root of the pinion and moving
toward the tooth tip and toe Load cases 1-4 and12-15 were double tooth contact regions whiletoad cases 5-11 were single tooth contact regionsNote that load case l l corresponds to the load atthe HPSTC For each load case using the bound-ary element method tractions were applied nor-mal to the surface to the appropriate ellipse withthe magnitude equal to the tooth normal force
divided by the ellipse areaCrack PropagaJion Simulalion The proce-
dure fer the three-dimen ional crack propagationsimulation of the OH-58 piral-bevel pinion wasas follows For each of the load case of Figure9 the mode I and mode IT stres inlensity factorswere determined at 25 points along the crackfront (note that for three-dimen ions there is acrack front not just a crack tip as in two-dimen-sions) The extended crack direction at each ofthese 25 points were detennined uing the modi-fied Erdogan and Sih crack extension theory asdescribed in the two-dimensional ana1ysis Thatis as the cracked spiral-bevel pinion tOOUl wasengaged in the me 11 the crack extension startedat each point along the crack front and grew in thedirection of the greatest tangential stress at thosepoints during mesh The amount of crack exten-sion at each point along the crack front was
determined based on the Paris crack growth rela-
tionship (Ref 18) where
lJ (J (~)nI -mar K
1~
Table I-Results of multiple Iliad case crack simulatiol1 analysis
Crack area(mm2I Crack front pointls)
Woad Icase torla rgest (leeStep
31201 12-25
2 11035
3
where (J was the amount of extension of the illlpoint along the crack front Ki wa the mode Istress intensity factor of the ih point along thecrack frontcerresponding to the lend ca e whichgave the largest tangential stress for that frontpoint KIrUU was the value of the largest Kli alongthe crack front lJHaX was the maximum definedcrack extension along the crack from and rr wasthe Paris material exponent From experience the
maximum extension size lImar was et to I27mm (0050 in) The Paris exponent n was set to2954 based on material tests For A[SI 9310 steel
by Au and Ke (Ref 4) A third-order polynomialwas then used to smooth the extended crack frontThe new crack geometry was then re-rneshedAfter re-rneshi ng the model was rem II and sol vedfor stress intensity factors and crack propagation
directions The above procedure was repeated anumber of times to imulate crack growth in the
gear toothTable I gives results from the rIC t four step
during this process Note that step 0 correspondsto the illitial half-eIHp e crack For steps 0 and 2the largest jangennal stress occurred at theHPSTC (load ca ell) for the majorilY of thepoiats along the crack front For teps I and 3 thelargest tangential stress occurred at load ca es g910 or 11
As previously stated the mode I and mode IIstress intensity factors were determined at 25points along the crack front This WIJI$ true forsteps 0 through 2 For step 3 however the modeI and mode Il stressintensity factors were deter-mined at 27 points along the crack front This wadue to the way the FRANC3D program extendedthe crack surface of the third step For tep 0through 2 the crack front wa a member of one
continuous geometry face (FRANC3D defines lt1
(3) geometry face as a 3- or 4-sided surface) For
Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
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APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
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IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
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FlARteR
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at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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Heel
Tooth
fillet
Cracksurface
Toe
Figure 12-0Bmiddot58 spiralbevel pinion tooth crackpropagation simulation after seven steps
Figure J3-Comparisoll ofOB58 spiralbellelpin-ion tooth crack propagation simulation toexperi-mentsstep 3 the crack front was a member of threeadjacent geometry faces thus producing 27 pointsalong the crack front
Figure 10 shows the stress intensity factor dis-tribution along the crack front for step 1 (crack areaof 596 mm2 (0009 in2raquo Similar to the spur gearanalyses K[ was larger as the load moved from theroot to the tip due to the larger load lever armOther than absolute magnitude the K distributionsalong the crack front looked similar for the variousload cases Figure 11 depicts the stress intensityfactors plotted against load case (at a point alongthe front biased toward the toe normalized posi-tion along the crack front of 083) This figureshows the simulated distribution as the pinionengages in mesh with the gear Note again that theratio of KI to K was not constant during engage-ment
noted that the loading was placed only at theHPSTC for the last three steps This was due tomodeling difficulties encountered using themulti-load analysis It was felt that this simplifi-cation did not significantly affect the results dueto the smoothing curve-fit used In addition thetangential stress near the crack tip was eitherlargest or near its largest value when the loadwas placed at the HPSTC
Comparison to Experiments Figure 13showsthe results of the analysis compared to experimen-tal tests The experimental tests were performed inan actual helicopter transmission test facility Aswas done with the gear fatigue tests describedbefore notches were fabricated in the fillet of theOH-58 pinion teeth to promote fatigue crackingThe pinion was run at full speed and with a varietyof increasing loads until failure occurred Shownill the figure are three teeth that fractured from thepinion during the tests (Fig 13b) Although thenotches were slightly dLfferent in size the frac-tured teeth had basically the same shape
A side view of the crack propagation simula-tion is shown in Figure 13a for comparison tothe photograph of the tested pinion in Figure13b From the simulation the crack immediatelytapered up toward the tooth tip at the heel endThis trend matched that seen from the tests Atthe toe end the simulation showed the crack pro-gressing in a relatively straight path This alsomatched the trend from the tests Toward the lat-ter stages of the simulation however the cracktended to taper toward the tooth tip at the toeend This did not match the tests One problemencountered in the simulation during the latersteps was that the crack at the heel end of thetooth became close to the actual contact ellipsesIt was felt that the crack-contact interaction mayhave influenced the trajectory predictions tocause the discrepancy
Spievak (Ref 22) reported on another methodto account for the non-uniform Ku to K[ ratioduring pinion tooth engagement This methodconsidered contributions from all load cases inthe crack angle prediction scheme and presenteda method to accumulate the load effects Fromthese studies reported crack propagation sirnula-tion of an OH-58 pinion also predicted the erro-neous taper toward the tooth tip at the toe endAgain the crack-contact interaction may haveinfluenced the trajectory predictions to cause thediscrepancy Spievak also reported on a simula-tion using only the load at the HPSTC The crack
Figure 12 shows exploded views of the pinion trajectories from that simulation were similar tocrack simulation after seven steps It should be the trajectories in the current study It should be
20 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGYmiddot wwwgeartechnofogycom bull wwwpowertrensmissloncom
ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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The new Mitsubishi Gear lechnology Centeris your siinsle source for the broadest arrayof gear production technoiogy in the worldFrom our patented high-speed dry cuttingmachines and hobs through gear shapersshavers and honing machinest to completestand-alonegear production centers
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If your current manu~acturingchallenges require the detailed focus of thewonds foremost authority on gear produc-tlonsive us a calliAfter alit were in theneighbo~hood
ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
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IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
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wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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Midwest Gear Corp2182 IEAurora Rd
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IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
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I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
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IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
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I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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ReferencesI Abersek B and J Flasker Stress Intensity Factorfor era ked Gear Tooth Theorerical and AppliedFracture Mechanics 1994 VoL 20 No2 pp 99-1042 Abersck B and J Flasker Experimental Analysisof Propagation of Fatigue Crack on GearsExperimental Mechanics 1998 Vol 38 No3 pp226-230 3 ~n MA AJ Tarhan and OS Yahoj LifeEstimate of a Spur Gear with a Tooth Cracked at FilletRegion Proceedings of lhe ASME DesignEngineering Technical Conference 1998 Athnta GA4 Au JJ and IS Ke Correlation Between FatigueCrack Growth Rale and Fatigue Slrialioil Spacing inAIS] 9310 (AMS 6265) Steel fracography andMaterial Science ASTM STP 733 1981 pp 202-2215 Blarasin A M Guagllano and L Verganj FatigueCrack Growth Predictions in Specimens Similar toSpur Gear Teeth Fatigue amp Fracture of EnRineeringMalerials amp Structures 1997 Vol 20 No8 pp1171-11826 Ciavarella M and G Demello Numerical Methodsfor the Optimization of Specific Sliding StressConcentration and Fatjgue Life of GearsInternational Journal oj Fatigue 1999Vol 21 No5pp 465-4747 Curtin TJ RA Adey lMW Baynham and P
pOIillUlransmssloncom wwgeueclnologycom GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 21
noted that the proposed method in the currentludy to account for moving tooth load for the
three-dimen ionaI analysis was extremely cum-bersome It is therefore felt that the analysisusing only the load a the HPSTC appeared accu-rate as long a the crack did not approach thecontact region on the tooth
ConclusionsA study to determine the effect of moving
gear tooth load on crack propagation predictionswas performed Two-dimensional analysis of aninvolute spur gear using Ule finite elementmethod wa investigated AI o three-dimen ion-al analysis of a piral-bevel piniongear using theboundary element method was discu sed Thefollowing conclusions were derived
I) A modified theory for predicting gear crackpropagation paths based on thecriteria ofErdogan and Sih was validated This theory slat-ed that as a cracked gear tooth was engaged inme h the crack extension started at the crack tipand grew ill tile direction of the greatesttangen-tial stress during mesh
2) For two-dimensional analy is crack sirnu-lation based on calculated stre intensity factorsand mixed mode crack angle prediction tech-ruques can use a imple tatie analy is in whichthe tooth load i located at the highest point ofsingle tooth contact
3) For three-dimensional analysis crack simu-lation can also use a simple static aaalysi in whichthe tooth load i located at We highest point of In-gle looth contact as long as the crack does notapproach the contact regien on the tooth 0
Marais Patigue Crack Growth Simulation forComple~ Three-Dimerraquo ional Geometry and LoadingProceedings from the 2nd Joint NASAlFAAJDODConference on Aging Aircraft 1998 WHliamsburgVA8 Erdogan F and GC Sih On the rack Extensionin Plates Under Plane Loading and Tran verse ShearJournal of Basic Engineering 13 Vol 85 pp519-5279 Glodez 5 S Pehan and 1 Flasker ExperimentalResults of the Fatigue Crock Growth in a Gear TootbRoot International Ioumal oj Fatigue 1998 Vol 20No9 pp 669-67510 Handschuh RF and TP Kicher A Method forThermal Analysis of Spiral Bevel Gears Journal ofMechanical Design 1996 Vol 118 No4 pp580-58511 Handschuh RFand FL Litvin A Method forDetermining Spiral-Bevel Gear Tooth Geometry fOJFinite Element Analysi NASA TP-3096 AVSCOMTR~91-Cmiddot020 199112Inoue K and M Kala Crack Growth ResistanceDue to Shot Peening in Carburized Gear Presentedat the 30th A1AAlASMEJSAEJASEE Joint PropulsionConference 1994lndia_napoJjs IN13 Lewicki DG and R Ballarini Effect of RimThieknest on Gear Crack Propagation Path Ioumaiof Mechanical Design 1997 Vol 119 No1 pp8amp-9514 Lewicki DG AD Sane RJ Drago and PAWawrzynek Three-Dirnensional Gear CrackPropagation Studies Proceedings of the 4th W~rldCongress on Gearing and Power Transmission ParisFrance 1999 Vol 3 pp231-232415 Lin HH RL Huston and JJ Coy On DynamicLoads in Parallel Shaft Transmissions Part I -Modeling and Analysis Journal of MechanismsTransmissions and Automation ill Desigll198B Vol110 No2 pp 221-22516 Litvin FL and Y Zhang Local Synthesis andTooth Contact Analysis of Face-Milled Spiral Beve]Gears NASA Contractor Report 4342middot AVSCOMTechnical Report 9QwC-028 199117 Nicolette G Approximate Sire s Intensity Factorsfor Cracked Gear Teeth Ellgineering FractureMechanics 1993 Vol 44 No 2 pp 231-24218 Paris Pe and F Erdogan A Critical Analysis ofCrack Propagation Laws Journal of BasicEngineering 1963 Vol 85 pp 528-53419 Pehan S TK Hellen J Flasker and S GlodezNumerical Methods for Determining Stress IntensityFactors Y$ Crack Depth in Clear Tooth RootsInternational Journal of Fatigue 1997 Vol 19 No 10pp 677-68520 Rice lR A Path Independent Integral and theApproximate Analysi of Strain Concentration byNotches and Cracks Journal of Applied Mechanics1968 Vol 35 pp 379-38621 Sfakiotakis VGbull DE Katsareas and NKAnifantis Boundary Element Analy i of Gear TeethFracture Engineering Analsis with BoundaryElements 1997 Vol 20 No2 pp 169~17522 Spievak LE SimulatLng Fatigue Crack Growth inSpiral Bevel Gears Masters of Science ThesisCornell University 199923 Wawrzynek PA Discrete Modeling of CrackPropagation Theoretical Aspects lind Implementa-tionIssues in Two and Three Dimensions PhDDissertation Cornell U ni versity 199124 Williams ML On the Stress Distribution at theBase of a Stationary Crack Journal of AppliedMechanics 1957 VoL 24 No I pp 109--114
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The new Mitsubishi Gear lechnology Centeris your siinsle source for the broadest arrayof gear production technoiogy in the worldFrom our patented high-speed dry cuttingmachines and hobs through gear shapersshavers and honing machinest to completestand-alonegear production centers
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If your current manu~acturingchallenges require the detailed focus of thewonds foremost authority on gear produc-tlonsive us a calliAfter alit were in theneighbo~hood
ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
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IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
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Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
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GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
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wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
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Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
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I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
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I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
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d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
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lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
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o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
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APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
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PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
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at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
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A very exceUentgear wordlbull
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
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Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
Home Page httpvVWwpurdytransmissonscomE-Mail salesputdytransmissionscom
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
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Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
Home Page httpvVWwpurdytransmissonscomE-Mail salesputdytransmissionscom
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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For addmanar tnlarmaltan on itiIlll~ andoT tluJctfOllgl QUI
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
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401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
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SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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CIRCLE 147
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marrufacwre bullbull to iIeIJIeI)COUllrm
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
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ALTERNATIIVE IGiEARMlANUFAC1iURING
This paper was Iprevi-ously presented at lhe
International Conferenceon Mechanical Trans-missions Chongqing
China AprU5-91
2001
------
- -
Net-Shape ForgedGears-The State of thleArt
Trevor ADean and Zhongmin Hu
A commercial process for forging bevel gears(Ising hot workpieces for automobile differential
i gears was available by the early I960s (Ref 1)
111IInIIii
~--------------------------------~ Ii
IntroductionTraditionally high-quality gears are cut to
shape from forged blanks Great accuracy call beobtained through shaving and grinding of toothfOnTIS enhancing the power capacity Life andquietness of geared power transmissions In the1950s a process was developed for forging gearswith teeth that requires little or no meta] to beremoved to achieve final geometry The initialprocess development was undertaken in Germanyfor the manufacture of bevel gears for automobiledifferentials and was stimulated by the lack of I
iavailable gear cutting equipment at that time iLater attention has turned to the forging of spur i
i
r--~~~~~--~i iii
IiI
IIiiiI
Figllre1-Flash bevel gear die
Top punch
and helical gears which are more difficultto formdue to the radial disposition of their teeth com-pared with bevel gears The main driver of thesedevelopments in common with most componentmanufacturing is cost Forming gears rather thancutting them results in increased yield from rawmaterial and also can increase productivityForging gears is therefore of greater advantage forlarge balch quantities such as required by theautomotive industry
Cold forging (forging wilh workpieces at roomtemperature) results in parts with the highest accu-racies Differential bevel gears can be forged cold tofinished geometry (net-shape) However it is nor-mally cheaper to forge them with a small amount ofexcess metal (near net-shape) and use a simplemachining operadonon their back faces to bringthem to finished size No machining of teeth is nec-essary Depending on overall geometry some spurand helical gears can be cold extruded with a net-shape tooth form But gears that have large diame-ter-re-width ratios-typical of those used in gear-boxes and other power transmitting systems-mustbe forged in completely dosed cavity tool usingpreheated workpieces Thus such gears are at bestnear net-shape and considerable efforts are beingundertaken to devise a second cold forming opera-tion that will improve their tooth accuracy to net-shape standard A cutting operation subsequent toforging results in an uneconomic processing route
It has been shown that forged gears have highertrength than cut ones and this offers the opportu-
nity for using them at higher power density ratingsThis is attractive where weight is II penalty such asin automobiles
Die clamping force
Bottom punOh
Bevel Gears
The accuracy of the tooth form of the as-forged
FigureZ-Flashless bevel gear die
gears was sufficient for the automobiles of thatperiod but the design of the forging tool resultedin flash being fanned (Fig I) Also post-forgemachining was required on the back race and thebore of the components Continual developments
26 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeart6chnologycom bull WWWpOW6ftfBflsmlssloflcom
of the process have resulted in tool sets with com-
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
Gleason Pfallteramp Gleason Phoenix
Liebherr Klingelnbergl- Oerlikon-Opal Hoeflerbull Hun_hbull Kapp-Niles SamputensilimiddotIMikmn-IMaagtsellel
We offer eur customelS Highest Accuracy Fas1est IDelivery
bull Competitive Prices Relapamp Illeplating Service
Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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CIRCLE 107
--_--------- bullbull ALTERNATIIVE GEAR MANUFACTURING~ ~~1111~~~~~~_-1pletely enclo ed die cavities (Fig 2) Using the e gear shaped so that the punch can slide in the eav-cavities it is possible to forge net-shape bevel tty and dose its upper end The load cell shown is
gears But mo l ofien the bore is ftllis formed in u ed for experimental purpose only and i 110tsubsequent operations not intheforging tool It likely to be found in commercia situations Amay be said with little qualification that the tech- gear i forged by placing a cylindrical billet on
notogy for forging radial-and spiral-toothed bevel the ejector in the cavity and squeezing it sideways
gears i virtually developed to it ultimate sage into the teeth of the insert under tlte force of the
of commercial refinement downward moving punch When the punch has
Spur and Helical GealiS moved upwards the forging is removed from theExtruded gear jOfflU Essentially two types of cavity by forcing the ejector upwards This design
forming processes may be used to form the e can be u ed only for spur gears asthe nece arygears If the aspect ratio (widthdiameter) is large rotation of thepunch to enable it to mate with athey can be formed by extrusion Iypicalextrud- helical die insert is not practicable An alternativeed part type are the tarter motor pinion and the tool design that is suitable for a wide range of
helical shaft gear shown in Figure 3 Depending spur and helical gear shapes is shown in Figure 6on the compo ition of the workpiece teel these The important features of this design that differparts may be extruded at room temperature (cold from the previous one are as followstanned) This results in high accuracy and the The die insert is supported on light spring andtooth forms usually do not have to be finish can move vertically guided by an external cylin-machined A gear of lower aspect ratio which has der The punch does not enter the die insert butbeen cold extruded is shown in Figure 4 A 0011- contacts it on its lop face Thus as the punch
iderable amount of metal has to be machined move downward it do es the top end of the diefrom the end faces which have been distorted cavity and pushe the insert downwards
during extru ion The los of metal in machining The diameter of the ejector i the arne as thethese faces will be a consideration in judging theeconomic viability of extra ion
Obviously the distortion arising in extrusion ofgears of even lower aspect ratio would render the
process uneconomical because the amount of metalto be removed would be 100 high a proportion ofthe total For this reason such gears are forged incavities in the manner or bevels However due tothe fact that the teeth of pur and helical gears radi-ate normally 10 the axis of symmetry they are moredifficult to forge than bevel gears
Forging machines amp tooliflg Forged geartechnology is directed to high-volume produc-
tion and the forging machine most suitable forthis is a mechanical pre s However virtually anyforging machine with contmllable stroke load orenergy having accurate guidance can be used ifeconomic considerations allow
Several forms of roo ling designs are usable forgear forging and the be t choice depends on the
geometry of the particular gear to be forged Asimple design that has been used to undertakeearly experiments at the University of Birmjng-ham in England is shown in Figure 5 (Ref 2)E senti ally il consist of a die jnsert with afemale form of the gear teeth to be forged in itsbore A gear-shaped ejector which can slidealong the gear teeth closes the bottom of the diecavity The periphery of the punch which iattached to the slide of the forging machine is
wporransmluioncom gltsrlschlloloQycom bull GEAR TECHNOLOGY JANUARYfFEBRUARY 2002 21
IFigure3-ExtrusionmiddotfoIgldgear fann
Fillur81f-Throughmiddotaxtrudmiddotelf spur gear -
Dr Trevor A Deanis emeritus profes or ofmanufaelllring illginltringat the University ofBinningham located inEngland He also I~leaderof tire metal formiIlg groupin lire IInilersitys school ofmurwfaclilrillll tmdmechanical engineeringThe group works 011
aspects of precision-form-ing tIIgineerillg campo-netus A mechanical engi-nflr Dean has worked 011
the forming of near-net andnet-shape sears for morethan 20 ear O1d haspub-lished more than 140papers on the subj(I
Gearmiddotshaped die insert Shrink ring Die Clamp ring
Dr Zhongmin Hui a IIsearch scientist inIhe University of Binni~lg-hams School of Manulllturfrg and MechanirolEngineering in Ihl
schools metal forminggraup A mechanica (ngimiddotneer he works 011 IIJI ne-shape forgillg of gearsaerofoil blades and othercomponents His mailresearch work is infiniteelement analysis frictionQlld lubrication and sur-face topograph)Qf fQrgilHproducts
Figurels-Slmple too] set design
Mandrlll WolIltpiece
figure amp-Gear forging tool sel with springcontainar
1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
J---1-I--+--i--~IFI--j-1 rr-r--r---+L-t
-02 I J II Productthermal I I
-l3 ~ ~------
04 -- -- r--Die ~re Oia 6350mm---r4-J
-os t--~ 1
I
Jj ------ Ibull Ult 46 i I
I II--H
Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
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MarchAprIl Heat Treating
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APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
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1-_~~~~~~~~~~A~[T~ER~N~A~J~IV~E~G~iEA~R~M~A~N~U~FACTUIRINGbullbullbullbullbullbullbullbullbullbull _ i mot diameter of the gear teeth allowing it to be ai simple cylindrical shapeI
Figure 7--Gorrectian factor in dies
02 Dieel-+-l -4--- I i I I01 L I I II 1-
Dietlgter~I-11 - - T--~=-1-middotT--1~t00 +-~-7TOO--750+-800r---_-t-IIOO+--i950r---l-+000~-1050+-- Il-oo-iso--t200--I
II ForgingTempeltature(C) I01
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04 -- -- r--Die ~re Oia 6350mm---r4-J
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Figure 8-Temperature variations
lemperature Range 1000 - 1250middotC Over ACI BelowAcl Room TempDecarbonized layer [mm) 03 - 04 010 - 025 01 0Roughness [Aa I gt 100 11m gt 50 JIm gt 20 11m gt 10 11mDraft lt 7 lt lt = OmiddotActura cy [11m) ~O5 - t10 toOS - fO2 to05 - to15 plusmn0005middot fOThickness (mm) to50middot 115 plusmn020 - plusmnD4D toIO - to25 to Ia - 1020Eccentricity [mmJ 05 -15 D1O - 070 010 - O4lI 005 - 025
-- ---
400c
i -g 300
3s 200secte 100
500
54
2 Vgtr--
2 3 4 567 aDisplacement(mm)
a) LoadidiSjllaoement CUIrEi
Figure9-load variation and tooth tilling
b) Filling stage or precislon forged geaf
A mandrel is mounted on the punch enablinghollow workpieces to be used Thus only a
small amount of metal has to be removed to fin-ish the bores
There are eighteen different practical configu-rations of the four elements of the tool set-punch insert ejector and mandrel-which may
be used on a press with one moving slide (Ref 3)
Each has advantages and disadvantages and thebe t design depends on the overall geometry of
tbe gear to be produced
Factors affecting accuracy The dimensionalaccuracy of a forging is affected by tooling and
the process by basically three factors shown dia-grammatically in Figure 7
Most die cavities are made by EDM and to
compensate for spark gap andor wire thicknesan allowance G on nominal dimensions is made
Elastic expansion of the die Ue is caused byforging pressures
Thermal expansion of the die VI occur as itis preheated to reduce thermal shock when forgoing is being undertaken at elevated temperature
Post-forging thermal contraction Uc of aforging made at elevated temperature occurs afterit is removed from the die
The relative magnitudes of die thermal and dieelastic effects can be seen by referring to Figure 8which shows values obtained for a steel forging ofnominal diameter 635 mm forged in steel dies and
which are qualitatively applicable to all sizes offorging n can be seen that as the temperaaire of theforging is increased the elastic expansion of the diedecreases This is because the strength of the work-piece metal reduces 3S temperamre is increased andstresses on the die wall are reduced Also it may beseen that the higher the forging temperature thegreater is the increase in forged dimension due to thethermal expansion of the die This is due to the
greater amount of heat transferred from hot work-piece to die at higher forging temperature The
greatest absolute effect and also the effect thatvaries most with change in forging temperature is
the thermal contraction of the forging From this fig-ure it can be deduced that dimensional consistencycan be achieved only if workpiece temperature andforging stresses are closely controlled As forging
stresses are related 10 billet size temperature andtool lubrication the whole production process-from incoming raw material to release of forging
from the die-must be executed with utmost controlif dimensional consistency is to be achieved In an
I
Z8 JANUABYIFEBBUARY 2002 GEAR TECHNOLOGYmiddot wWW9eSflechnologycom bull wwwpowrlr~nsmissioncom
_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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~UN_U8Pht3l~- 32OI1IM2ID
Err-aII ~~
pawerlrllnsmlssoncom wwwgesrtchnoagycam GEAR TECHNOLOGY JANUARYFEBRUARY 2002 391
CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
I
onmMilRoo bullbull Warren MI middot1109
CONTACTCRAIG 1)1RGSS(586) 754middot8923
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
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401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
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SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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_----------ALTERNAnvE GEARMANUIFACTURiING _ideal situation ifthennal di tortion could be predict-ed and contmlled preheating billets alone would notaffect accuracy However practical limitatiolls ontemperature control and the sensitivity of dimen-sions to temperature leads to the situation that accu-racy decreases as forging temperature increasesThu unheated (cold) fbrging is the technology thatenables the greatest accuracies and the rna t consis-tent dimensions to be achieved in forging produc-tion Accuraeie typical of cold- hot-and warm-fo~ged components are given in Table 1
o reduce elmiddot tic eli Ionian of the die loads andIre s must be kept as low as possible Ftgure 9
shows the load associ ated with a given level of toothfilling during a forging operation A noticeableincrease in load arises whenihe workpiece reacheshe roots of the teeth in the die cavity (Point 1)When the metal reache the tip of the teelh in the diecavity the load increase with ram displacement isvery rapid and increases dramatically asthe comersare filled As the comers of gear teeth are usuallychamfered it is possible not to forge them fully [0
the case of the example shown a load reduction ofabout 50 could be achieved Mathematical treat-ment of the distortions arising in tooling describedabove enable computer-based predictive programsto be developed so thai corrections [0 cavitygeome-tries may be introduced during manufacture so thaithe teeth of forged gears may be close to the speci-fied hape Figure 10 ltRef 4) show the variation inforged tooth profile thai arise with changing work-piece temperature as predicted in theory andobtained experimentally for a 13-tooth gear with508 module and 20 pre ure angle Figure lOashows hat at room temperature theoretical forgedand die tooih profiles are closely matched above thebase circle and the forged base circle correspondsclosely to that of the die The tooth forged al10000 C (Fig lOb) is smaller than that of the die asis fhe base circle diameter The differences betweentheoretical and experimental profiles between baseand root circles is because the computer programwas not arranged to allow for undercutting of heteeth that was machined into me die
Forged gears Net-shape processing routes forboth spur and helical gears are under considerableinve tlgation by 11 number of in titutionsObviously whether or not a gear form is net-shapedepends on the quality tandard peeified by thecustomer But as it appear that forged gearsarelikely to be commercially viable when made inlarge batch quantitie bull the standards being aimedfor are those of automotive manufacturers Foruse in gearboxe ISO standard grade 5 i
l~
~ Forged tooth profile
experiment)a) Superimposition or lIIe experimentally obtainedprolile of a forged tooth on Iheoretlcel profiles of thecorresponding die III1d final lor919 for forging atroom temperaturE
Ii1 prama (apenment)
b) Superimposition oll11e eXl)Erimentalty obtained proilie 01 IIforged tooth on tIleoreticel proflles of 1118CQT9Spondlng dieand final forging for forging at IOOOmiddotC temperature
Forged tooth
Figur1D-Thearetlcal andactual toath profile
Tool changlng sysl9m
WaJm forging press
StlUal(Coldsindparts)
Cold lubncanon line
Still II
IIrWWpOWIIJIlsmissioncommiddot wwwgearIIJchn0ofiycom bull GEAR TECHNOLOGYmiddot JANUARYIFEBRUARY 2002 291
lliigure 12-Equipmenllayoutfor warmcold fO~ling
~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
Tell Us What You Think If you found this article of interest andor usefulplease circle 311If you did not care for this article circle 312
30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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586 Hilliard Street POBox 1898 Manchester cr 06045-1898 USATelephone 860 649-0000- Fax 860 645-6293
Home Page httpvVWwpurdytransmissonscomE-Mail salesputdytransmissionscom
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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A very exceUentgear wordlbull
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~_~~~~~~I~~~A-~LTER~N~A~JI~V-E~OE~-A~R~M~A~N~U~IFACTURING bull
[IJI_I tral hole and finish forging in a die with appro- priate peripheral tooth form The operations are
shown diagrammatically in Figure 13 The resul-
mups_81 tant forging is II near net-shape gear and is over-sized by between 01 mm and 02 mm on all sur-faces The gears are cooled cleaned and coatedwith a lubricant suitable for cold forging Theytmiddot
Punch Scrap are then passed through an ironing die to bringthem to specified dimensions his the cold-fin-ishing operation that is still the subject of inten-sive research activity
A drawing of the tool set used at the University
of Birmingham is shown in Figure 14 Figure 15isa photograph of the tool set mounted on a crankpress A schematic of the ironing die is given in
Figure 16 Some preliminary results from a gear-ironing operation are given in Table 2 Theimprovements brought about by ironing are obvi-ous but the quality of the ironed gear is le stham
ISO grade 5 One of the reasons for this is that thequality of the ironing die was not high enough
Coneluding RemarksThe technology for net-shape forging of spur
and helical gears is now weI esrabli hedThe major remaining task is to develop a
forming technique by which teeth of high accura-cy may be produced with good productivity and
Figare 13--forging s1lIges ofDlgeBf
Figure 15--Jhoto of gearforging die
Figure 14-Drawingl 01gear die
Figure 16--Schematic ofgear ironing die
left Hand Right Hand LH RH lH RHPressure Angle (1 012 010 I 073 058 019 016Involute ~ml 15 13 57 46 27 22Tooth Trace (iJml 8 5 105 94 93 66
I Max Cum Pitch (~ml 38 25 180 163 113 101Adj Pitch (~ml 12 9 73 28 21 116Tooth Thickness (iJm 31 12 468 285 55 46Hunout Ium] 32 96 62
requiredexcept for the reverse idler gear whichmay be ISO standard grade ]0 Currently inves-tigations are underway at the University ofBirmingham with the aim of developing commer-cial processing routes for the three gears hown inFigure l l It is envisioned that a shop floor set up
similar to that shown in Figure 12 will be utilizedBillets are sawed or sheared from rolled bars with
circular cross-section weighed heared to aboutWOdegC and coated in a water-based graphite lubri-cant They are then heated in a second inductionheater to a preheat temperature appropriate t0 thesize shape and alloy of tile gear That temperaturewill normally be in the region of 900deg C which iswithin the warm forging range The billets arethen forged on the first press in three operationsupsetting (squeezing them in a cylindrical diecavity) to produce a prescribed diameter and acentral web piercing of the web to produce a cen-
at acceptable costsAcknowledgments
The experimental work reported in this paperwas undertaken with support of the Engineeringand Physical Science Research Council of theUnited Kingdom
RefuencelI Lacy K Hot Forged Gears to Pine TolerancesMetalworking Production 19672 Sadeghi MH and TA Dean Analysis of DimensionalAccuracy of Precision Forged Axisymmetric ComponentsProceedings of Institution of Mechanical Engineering PanC 1991 2053 Tuncer C and TA Dean Die Design Alternatives forPrecision Forging in Completely-Close Die CavitiesProceedings of the 25th Iniernational Machine TooDesignand Research Conference 1985479-4834 DeIl11 TA Precision Forging of Spur amp HelicaJ gearForms Proceedings of Drives amp Controls ConferenceBritish Gear Association Annual Congress 199766-725 Abdel-Rahrnan ARO and TA Dean The Quality ofHOi Forged Spur Gear Porms Part I Mechanical ampMetallurgical Properties International Journal ofMachine Tools amp Malltlacllre Design Research andApplication 1981 Vol 21 No2 109-127
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30 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwQeartechnaragycam wwwpawertransmissoncom
_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
THE PURDYCORPORATION
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
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If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
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APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
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l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
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FlARteR
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
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_----------ALTERNATIViE GiEA_R MANuFACTURING -- II
rolling velocity is (vl+vZ)J2With thiste ring method the typical
loading and sliding conditions of plasticgears can be simulated (Ref 15) Gearswere tested using a back-to-hack lestconfiguration (Refs 7-8 13-14 and 116)The material used were PA66 (RWOO)and short-glass-fiber reinforced PA66(RFL4036) (Ref ]7) The proportion ofglass fiber added was 30 by weight 0
ensure proper contact along the facewidth of the disc all of the specimenswere prepared by machining 20 11mfromthe molded surface and then polishing toa surface roughnes of around 5 11m
Yong Kang Chen Nlick Wright bullChris J Hooke and Stephen N IKukurekal
IntreducelonPlasacsas gear materials represent an
interesting development for gearing be-cause they offer high trength-to-weightratios ease of manufacture and excellenttribological properties (Refs 1-7) In par-ticular there isa sound prospect that plas-tic gears can be applied for power tran -mis ion of up to IOkW (Ref 6)
Typical pIa tic such polyamide 66more commonly known as nylon 66have long been known as uitable mate-rials for gearing Wt was reponed thatpolyamide gear experienced fatiguefailure before significant wear wasob erved (Refs 6-7) but crack initiationand propagation mechanisms wereunclear The failure mechani m ofpoJyamide 66 (PA66) gears when run inlike pairs are still not clear (Ref 6-15)and as 11 result bullPA66 users have to sub-stantiajly underrate their designs forgears
In a previous study (Ref 15) arolling-sliding te t rig for other types ofplastic gears has proved capable ofmeasuring both friction and wear contin-uously during tests This has enabledconsiderable detail to be obtained aboutI~----------------------------------------------------~
the wearprocesse in polymer gears Thetests are thus a versatile way of studyingwear mechanisms in Order to contributeto accurate life predictionfor gears
This pre ent work was thusinitiatedto study wear and friction mechanisms ofPA66 and it composites It was hopedthat this investigation would enable thefailure mechanism of PA66 gears 10 beinterpreted
ExperimentaJ AppaxstusandProcedure
The twin-disc wear testing machineu ed in our previous work (Ref 15) wasagain employed in this investigationWith (his machine measurements ofboth the frictional force and wearbetween two discs ill contact can bemade continuously so that both the wearprocess and frictionbehavior during testscan be monitored Experiments were car-ried out either at different slip ratiounder a given normal load or al differentloads with a fixed slip ratio
Slip ratio is defined here as the ratiobetween sliding and rolling velocities Ifthe tangential velocities on both contactsurfaces are VI and v2 respectively thenthe sliding velocity is (vI-va) and the
03
1O~
-6- IJnreinforced PA66- - 30 shert-qlass-fiber reinforced PA66
Slip ratio
DrYong Kang Chenis a senior lecturer if the aerospace civiland mechanical engineering depamnent atthe Univeristy of Hertfordshire located illHatfield Eglcmd Cilerl $ research interestsinclude tribological chnrocltrizalioll ofpolymers and polymer composites Gild
fatigue assessrmml of composites
lOrNick Wrightis II tnalerialmiddot deeopmelll engineer willICosworth Racing Ltd located inNorthampton England He is responsiblefor developing materials and processes forbuilding racing engines used ill Formula 1CART and World Raf) Car He holds adoctorate in lilt fribK) of polymer matrixcomposites for gearing applicaiions
Dr Chris J Hookeis a research scientist il applied mlchallicsin the University of BirminghamsEngineering School located in EdgbostoraquoEngland HI has published more 11111l50papers Oil trlboloK) He has researched theVeal medwlII~llu 0 polymers ill IIIlubFimiddotcared concentraied contacts such ax gearand their relationship to surf act tempera-lure and stress sliding spud and materialcompositioll
Dr Stephen N IKukurekalis a senior lecturer ill ~IlIinlerig at thUniversity of Birmingham s lnstitute ofMtwIIITgy and Materials Science locatedin Birminghasn Engtand Hi holds a doc-torate in male rials science and has writtenmore than 40lJapers 01 polymtrs cmd cam-posltes
Filure 1-Wear ~ate lIersUsslip ratio for PAampampat 200 N and 1Il00 lJIm and for 3U by wei ght short-gllass-fiber reinforced PoS1i6atlOO N lamll 11000rpm~
WWWpowBrtfllftSmlssloncommiddot wwwgurtechnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 3~
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
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b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
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f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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CIRCLE 107
III ALTERNATIVE GEAR MANUFACTURING bull1
1(t4 1 1 1 1 I 16 Unreinfarced PA66 at 004 slip ratio Glass-fiber reinforced PA66 at 004 slip ratio
6
lti1O-~ E 6
u -~E3- l El 6~ ro 10-6 t- 6~
10-) 1 1 1 1 I 1
0 100 200 300 400 500 600 700Normal load (NI
Figura Z-Varialion of wear rate wilh normal load for PAG6 and PA66 composite runningst 1000 fpm
Both the discs were 30 mm in diameter
and ]0 mm in face widthBefore testing the samples were
cleaned with methanol They were then
run at the test conditions for an extendedperiod to remove the machining asperi-ties and any subsurface layer affected bythe manufacturing process After running
them they were dried at 700C for 15hours to remove any absorbed water that
might affect the measurement of wearand then weighed Finally they were leftunder atmospheric conditions for about
two weeks to allow the water content toreturn to equilibrium conditions
After this preliminary treatment the
specimens were remounted in the test rig
in an identical position to that underwhich they had been run-in Tests wererun for running peed of 1000 rpm andata range of loads and slip ratios The
slip ratios used were between 0 and 028Tests were performed under dry unlubri-cated conditions at ambient temperature22plusmn i)degC until failure or for up to 10contact cycles
At the end of the tests the discs wereagain dried at the same temperature andfor the same rime period as they werebefore they were tested Then the discs
were weighed to measure the weight lossof each disc With this drying procedurethe measurement of wear by weighing isaccurate to about plusmnW-5g Finally the
worn surfaces were observed in detail byusing a mOL JSM6300 scanning elec-tron microscope
Figure 3--TypIcal PA6Ii worn sur1ace Funning atDOOislip ratio 3Z MPa and 1OOO rpm di rectlon offricti on force from bOIlOmllO top
Figure 4--Transverse cross section through thodisc paraUel to diredionof friction foree runninglat 014 slip ratio 32 iMPa and 10110rpm directionof friction fnrce from Ileft to right
IAgure 5-Geomotry andl dimension of tvipicaldebris to be produced on the PA6Ii worn sulfacerunning at 8Iransition slip ratio 0011 32 MPand 111100rpm direction of friction forcefrom lopto bottom
i Experimental Results Wearrate Wear rate is defined here as
11 the average depth of material removedfrom each disc per rolling cycle (Refs 15
and 18-19) and was calculated by meas-
11 uring the weight loss of the specimensFigure I shows how the wear rate of
i unreinforced PJ66 varies with IIp ratio1 for a fixed normal force of 200 N and a
I
I
II
1
I
i
constant running speed of I 000 rpm Itcan be seen that slip ratio has a ignifi-cant effect on wear rate The wear rate
rises slightly with an increase of slip ratiowhen the slip ratio is less than 009 at
which point di colored material appears
011 the contact surfaces during the testsThe wear rate starts to increase sharplyfrom 20 x 10-6 urncycle to 70 X 10-5
urncycle as the slip ratio increases from006 to 009 and the wear rate reaches itshighest value of 104 jlmlcycIe at a slip
ratio of 011The unique characteristic property of
this material is that a furthermcrease illslip ratio from 011 resultsin a dramaticdeerea e in wear rate When the slip ratioincreases to 014 the wear rate decreasesrapidly from 10-4Jlmlcycle to 80 x 10-6
Ilmlcyc1e and discolored material returnsto the contact surfaces The difference
between the two wear rates is more thantenfold while that between the two slipratios is approximately 27 After this
considerable decrease the wear rateincreases slowly to 10 x 1()-5 Jlmlcycle
as slip ratio increases to 021 ]t is sug-gested that the slip ratio of 0_11 is a crit-ical one corresponding with maximumwear rate
Figure 2 shows the effect of normalload on the wear rase at 11 given slip ratioand running speed (at 1000 rpm with aslip ratio of 0(4) It can be seen that thewear rate varies in the range from 2_0 x1O) j1mJcycle to 40 x lO) unfcycleWhen the load is between 300 N and 500N the wear rate statts to increase signifi-cantly from 20 x 10-6 urncycle to 30 x
10-5 Jlmlcyc1eThe effect oj short-glass fibers
Reinforcement with short-glass fibershas significant effects on wear and fric-tion As shown in Figure 1 both wear
32 JANUARYFEBRUARY 2002 GEAR TECHNOLOGYmiddot wwwgeartechnoJogycom wwwpowertrsnsmissloncom
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
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wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
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auick Turnaround
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MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
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I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
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CIRCLE 107
I
J_----------ALTERNATIIVE GEARIMANUFACTiURING _and friction are dominated bythe abilityor inability of a thin layer of self-lubri-cating film to be formed continuouslyand to be retained on the surfaces in con-tact (Ref 18) Similar to the case forPA66 at low slip ratio when the filmwa found on the contact urface weardebris could hardly be Db ervedand fric-ucncoefficient was less than 01 UnlikePA66 once the film was disrupted thefriction coefficient of short-glass-fiberreinforced PA66 varied between 025and 03 while that of unreinforced PA66was in the range of 042 to 072
Figure 2 shows the effect of normalload 011 the wear rate of 30 short-glass-fiber reinforced P1I66 compo ite at afixed slip ratio of 1104 and a constantrunning peed of l(JOOrpm Here thewear rateincreases uniformly ana loga-rithmic scale from I 01umcycle to ]35x lijc5 urncycle a the normal loadincrease from 100N to 500 N
Figure 1 shows the wear rate of 30shen-glas -fiber reinforced PA66 com-po ites as a function of slip ratio for 91
fixed normal force of 300 N and con-stant funning speed of 1000 rpm Theself-lubricating film on the contact sur-faces exists during all of Figure 1 swear-rate measurements It can be seenthat the wear rate increases nearly loga-rithmically from 10-6 urncycle to 1OS
jlmcycle as the slip ratio increases from004 to 021 The wear rate is of thesame order of magnitude as that ofunreinforced PA66 apart from theunique peak in the wear rate
DiscussionThe wear mechani rns of di cs can
be used to explain wear behavior of gearteeth Figure 3 shows the early stage of ageneral surface damage on 3 disc afterrunning for 58 x 1()6cycles when theslip ratio was 006 and less than its criti-cal value of 0]1 It can be seen that thelength of these cracks varies from a cou-ple of micron 10 len of microns Thesecracks eventually propagated across thewhole width of ihe disc and were per-pendicular to the direction of the frictionforce that moves from hebottom to thetop
FigUICe4 show a section through thedisc parallel to the direction of the fric-tion force when the slip ratio was 0]4which is greater than its critical value ofO11It can be seen that the typical widthbetween two fully developed cracks is200-400 um and that the distancebetween two sub-cracks is less than lOOlm This can be comparee with thismaterials typical Hertzian contact width
of 400-980 urn (Ref 19) It can be seenthat as shown in Figure 4 the maincracks initiated in the radial directionperpendicular to the friction force Theilthey propagated ill a direction at an angleto tile friction force instead of perpendic-ular to the friction force The depth towhich the main cracks propagated variedfrom 150lm to 450 urn
Between these main cracks there
UNIVIRSITYrWISCONSIN
lMMllLWAUKEE~-- -
Gear Technolo9ySeminarspresented by Ray Draqo P E
bull IFulndaimentals of Gear DesignMay s 0 and September 11-13 2002
Brief HistoryGear NomenclatureDrawing Data Requirements
formats and SpecificationsTheory of Gear looth ActionGear Types and Arrangements
1 Advanced Gear Design amp TheoryMarch 20-22 and lDecember4-6t 2002
Review of Fundamental ConceptsManufacturing lnspectlon olnd QCMaterials and Heat TreatmentLubrication Types and Methodsload Capaci1y Rating BasicsFcilure Modes amp Prevenflon
All presentations supported by extensive physical gear sampleshandouts of presentation graphics and detailed text materials
All courses are held in Milwaukee WIFor course details go to our web site at
VlIIOIVengoulreachuwmeu
wwwpowsrlransmlssloncom WWWgS8fI8chnologycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 33CIRCllE 130
1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
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APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
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l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
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SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
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CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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IDirect your inquilies tDRon Humphrey General Manager
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
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Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
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------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
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1II AIlTERNATIVE GEAR MANUFACTURING _were some sub-cracks The main crackspropagated up to 450 11m and tile smallcracks propagated to about a quarter ofthe depth of the main cracks These sub-cracks eventually joined the main cracksAs shown in Figure 4 a sub-crack initiat-ed from the contact surface and propa-gated in an arc towards the adjacent maincrack Since the sub-crack is wider at hecontact surface than beneath it it is sug-
gested that the small crack was initiatedfrom the contact surface rather than frombeneath it (Ref ]9) Some cracks propa-gated to join their neighbor and as aresult the material between the twocracks was fractured severe spallingoccurred and debris was fanned It wasnoted that the crack propagated and frac-tured gradually rather than suddenly This compares well with the wear
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observed on a PA66 gear tooth surfaceas shown in Figure 8
Figure 5 shows a general view whenthe slip ratio reached irs critical valuethat is 011 Tile worn surface showsunique characteristics but is not discol-ored A large quantity of roll-like debrisis attached to the surface and tends toaccumulate on the surface It can be seenthat roll-like debris consists of the mid-dle part of he mil and two tails on bothsides The length of roll-like debrisvaries from tens of microns to a coupleof hundred microns The diameter of themiddle part is about LO-1O0 11m A tailhas a very small diameter (about 01 11m)and is very long (about 100 11m) Mosttails were broken and separated fromtheir body during the friction process
It was observed that before roll-likedebris on the worn surface was fannedthe surface suffered a very deep sheardeformation and surface material movedin the direction of friction This de-formed material was gradually rolled inthe direction of friction Asa result thebody of a piece of roll-like debris wasformed as shown in Figure 5 It wasnoted that there was overall a great dealof debris collected during the test andthat it appeared very thin and lang Sincethe slip ratio along gear tooth profile incontact varies and covers the lip ratiorange of 0-028 it is suggested that fail-ure mechanisms of PA66 gears are severewear due to a critical slip ratio and toothfracture due to macrotraasverse crackson the contact surface
The reinforcement of PA66 withshort-glass fiber also has an effect ontransverse cracks which occur whenPA66 is in non-contormal tolling-slidingcontact Although the wear mechanismsare very complicated as shown inFigures 6-7 no transverse cracks on theworn surfaces were observed under avariety of test conditions
Because of the film on the surface asshown ill Figure 7 the friction coeffi-cient can be below 01 and as a resultthe shear tress at the interface betweenthe filius should be low This low shearstress may play an important role in the
self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
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Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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marrufacwre bullbull to iIeIJIeI)COUllrm
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addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
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self-lubricating property of the compos-
ite Also becau e of the low frictioncoefficiem the maximum heal tres inot at the contact surface but 011 the ub-
urface and there i little chance for atran verse crack to initiate on the contacturface (Ref 18)
Figure 6 how a surface in theevere weal stage obtained from a di c
run at 1bull000 rpm with a 300-N load anda 028 slip ratio It can be seen thai thefibers on the urface were highly aligned
and approximately parallel 10 the frictionforce Figure 6 also indicates that both
long and bon broken fibers can move onthe surface causing alignment from aninitially random di tribution It iob erved that the aligned broken fibersdo not remain on the urface indefinitelybtl are expelled oul as debri It appeaTh
that in the rapid wear ct~ge wear is dueto the removal of unworn but fragment-
ed fibers rather fhan 10 their gradualabrasion Thi also compare well withthe wear observed at the composite gear
tooth surface as shown in Figure 9These test results clearly explain why
PA66 gear teeth fracture near the pitchlinearea with little debris where the stid-ing ratio between gear teeth in mesh ivery small IRet 6-8 and 13) Fromlheabove tudy of non-conformal unlubri~cated rosling-sliding contact one of thedominating factors in surface failure atlow and high hp ratios ilnulsversecrack propagation 0[1 the urface in con-
tact Also there was not much debrisbefore cracks fully developed andspalled Since the slip ratio on the gearteeth in contact varies and is around0-021 near the pitch line (Refs 6--8 and
13) the behavior of crack propagation 011
n gear tooth urfaee hould be imilar tothai on di c surfaces In other word
the e cracks 011 a gear tooth propagatenot only across the gear face width bUI
also into the subsurface of llIe gear loothAfter a certain number of cycle the
crack win propagate down to a depth of05 mm near the dedendum of a geartooth-in the region near initial conta I
on a driving gear tooth-where a high lip ratio i expected and near the pitch
line area on the gear tooth where a [ow
lip ratio occurs For a gear of module 2mUI a reduction of 05 mm of the tooththiekne near the dedendum i consider-ably signifiearu Sire eoncerurauons at
the tip of cracks are severe Therefore
the bending stress on the dedendum ofthe tooth could be much higher than thetooth was designed for Near the pitchline area on a gear tooth correspondingto lower slip ratio bull bending tresse arehigh since this is the position where onlya pair of gear teeth are in contact Crackpropagation al lower slip ratios will also
cause severe sires concentrations at thetip of cracks if the [ooth is subjected 10 a
rea onably higher bending momentUnder high bending stresses it is sug-
ge ted that the severe tress concentra-
tion re ults in the tooth fracture near thepitch line area 011 the gear toothTherefore it i uggested thattooth frac-ture in PA66 gears is due to initiatien andpropagation of transverse cracks rather
than creep as shown in Figure 8Conclusions
The failure mechanisms of polymer-ic (PA66 and PAM composite) gearhave been investigated by testing plasticagainst plastic in counter-conformaluolubricated rolhng-sliding contact overa wide range of slip ratios loads andrunning speeds Comparisons betweentests on discsat varying slip ratiosandthe result of gear te IS under compara-ble conditions have been very favorable
The wear and friction behavior ofPA66 was dominated mainly by threemaj r feature a critical slip ratio undera fixed load and running speed mnero-transverse cracks and a layer of lilm on
tile contact surface These results corre-sponded clo elyto the failure phenome-na of PA66 gears It is uggested thai the
transverse cracks caused the plastic gearteeth to fracture even near the pitch lineThe rnacrotraasverse cracks in Ilte gearteeth on the contact surfaces are OJ seriou di advantage of PA66 gears
To remedy thi the effect of rein-fereem ms of hort-glas fiber on th wearand friction behavior has been tudiedDoth the wear and friction propertie of
IFigure 6-AlIgned broken fibers on Ih- compos-ite surface aher disruption 01 thel surface laJar102B slip Iratio Ii3 MPa and 10001rpm~ direction01 rleli on orce from ibottom to top
Figure l-Transvers8 C~Dss sectiDn of typicalsulface Wm 0111tb= contact sllJface of IbollmiddotgJlIssfiber reinforced PA66running et 1)000 rpm004 slip ralio and 113Mfa direction at frictionfOrCII from leltlo right
IFigure B-TYP[cllsurflca topogrlphy II~ 11 PA66illar running at 11500 rpm andl maximum contactstress of19 IMP I ahe r 225 x UJIi cycles
lliillllfl ~TVJlicll luncI future 011 be corIblClIlLrfUI of sbol1middotIIlaslmiddotfib~r IlIinforeed ~A66drivmiddotling gear running t UiOO rpm and 166 MPal after 22)x11J6cycles (Pilch lin not in pIlDtD T1 pltl
portllnmuoncom wwwSftlllrtltchnologycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 35
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
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36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
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For addmanar tnlarmaltan on itiIlll~ andoT tluJctfOllgl QUI
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
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If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
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We offer eur customelS Highest Accuracy Fas1est IDelivery
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
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GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
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AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
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bull Wormlbull SpurI Helical
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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CIRCLE 107
CIRCLE 328
4 Yamaguchi Y Tribology of PlasticsMaterials Elsevier New York 19905 Guicheaar PJ Bernard S Levy andNM Parikh Gear Manufacture andPerformance American Society forMetals Orno USA 19746 Crippa G and P Davoli Fatigueresistance of polyamide 6 gearsKunststoffe 1991811477 Mao K CJ Hooke and D WaltonThe wear behaviour of polymer com-posite gears Synthetic Lubrication [I~~~~~~---------
1995 12 (4)337 18 Breeds AR SN Kukureka K Mao bullD Walton and CJ Hooke Wear 1993 ~ I
16685 I If youdidnotcare for this articlecirele315 I9 Clerico M A study of the friction i
and wear of nylon against metals Wear i If you would like to respond to this or any1969 I3 183 i ~her article in this edition of Gear
echnology please fax your response to the10 Clerico M Sliding wear meCha- attention of Randy Stottmanaging editor atnisms of polymers Proceedings of the 847-437-6618 or send e-mail messages to
peoplegeanechngycomInternational Conference on the Funda- i1 ---1
unreinforced PA66 were improved COIl-
siderably by the reinforcement of 30by weight short-glass fiber This rein-forcement prevented both the initiationand propagation of transverse cracks onthe contact surfaces that occurred in theunreinforced material Also it decreasedboth the wear rate and the friction coeffi-cient substantially A thin fi1m on thecontact surfaces was observed andplayed a dominant role in the self-lubri-cating behavior of the composite and insuppressing the transverse cracks Theseresults offer the prospect of enhancedapplicability of polyamide 66 in gears
AcknowledgmentsWe would like to thank Brian Duke
of Davall Gear Co and Davall MouldedGears Ltd for the supply of several com-ponents of the test rig and for many use-ful discussions
ReferencesL British Standard BS 6168 Specifi-cation for non-metallic spur gearsLondon 19872 Polypenco Gear Design PolypencoCorp USA 19853 Drago Rl Fundamentals of GearDesign Butterworths Boston MA1988
mentals of Tribology NP Suh and NSaka Eds MIT Press MA USA19787691L Clerico M and V Patiemo Wear19795327912 Clerico M Wear 19806425913 Hooke CJ K Mao D Walton ABreeds and S r Kukureka Measure-ment and prediction of the surface tem-perature in polymeric gears and its rela-tionship to gear wear Transactions ofthe ASME Journal of Triboiogy 1993Vol 115 p 11914 Hooke C 1 K Mao D Walton ABreeds and SN Kukureka Temper-amre prediction in polymer gears 3rdWorld Congress on Gearing and PowerTransmission Paris 199215 Kukureka SN YK Chen CoJHoole and P Liao Wear 1995 185 116 Wright N Polymer Matrix Com-posites for Power Transmission Ele-ments MPhil dissertation University ofBirmingham Birmingham United King-dom 1996 17 LNP Engineering Plastics Inc in AGuide to LNPs Internal LubricatedThermoplastics USA 199418 Chen YK SN Kukureka and C JHooke Journal of Materials Science199631564319 Chen YK Tribology of polymers inunlubricared rolling and slidjlg contactPhD dissertation University of Bir-rningham Birmingham United King-dom 1996
This Ipaper was previouslV presentedalthe fh World Congress on Gearing andPower TransmIssion in IParisMarch 1999
Tell Us Whar YoUThink
If you found this article of interest andoruseful please circle 314
36 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgeartechnologycom bull wwwpowertransmissioncom
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
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wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
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CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
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l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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CIRCLE 147
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I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
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I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
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------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
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CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
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CIRCLE 107
_----------AILTERNATIIVE IGEAR MANufACTUR~NG _
case and a core die The rough gear is placed inside the core dieWhen the core die i forced into the tapered die c e the core
die deforms el ticaUy hrinking inward as irs pushed throughthe die ca e Thai inward force form the crowning on the gearteeth When the core diei removed from the die case it returnto it original form expanding away from the part and enablingthe crowned teeth to be removed easily from the mold
Another unique aspect of the Createch die sets i thatthey areequipped with at mechanism to rotate (he core die during ihecrown forging process The friction caa ed between the core die
and the workpiece helps create a homogeneous stre distribu-lion and symmetrical crowning of the tooth nanks Ishida ay
~t also allows for continuous metallic fiber flows at the gear rootproviding high fatigue strength and pilling re [stance
The Createch die sets are made For conventional forging press-es induding hydraulic knuckle link motion am mechanicalpresse commonJy used for forging operations They are mo-tapplicable for high-precision gears such as gears for planetary
reducers and ill some automotive applications says Ishidain e 316
Technology Tidbits
Japanese Companies DevelopIHigh-Strength Plastic Gears
Shin-Kobe Electric Machinery Co Ltd of Tokyo has devel-oped plastic secondary balance shaft gears that greatly reducethe noise ill four-cylinder automobile engines according to thecompany
Plastic gears have been u cd in automobile engine for manyyears-Shin-Kobe developed its flrsl phenol resin balance haftgear ill 195S-but ihis is the first instance they have been usedfor the secondary gear which rotates twice as fast a the pri-mary balance hafl gear Until now steel gears were required for
that application according to Akikazu Tazawa manager of
wwwpowffrransmlssloncomW WI1Urechnolol1ycom GEAR TECHNOLOGY JANUARYFEBRUARY 2002 31
INew Technique for Forlging Cmiddotmwned Helical GearsCreatech Co Ltd II forg-
ing die manufacturer fromShizuoka Japan has devel-oped a net- hape cold-forging
process for forming helicalgears and splines with
crowned teethThe proce is being tested
by bpanese automotive manu-
facturers to replace conventional forging and machiningprocesses Potential advantage include improvement in gear
noise pitting re i lllilce and fatigue strength says HitoshiI Ilida Createcb pre ident and founder Also [here ithepos-ibility of eliminating processe such as tooth shaving or tooth
grindingThe proces is capable of fanning gear teeth to ns 2-3 qual-
ity for pacing error toolh profile error lead error with crown-ing and runout according 10 Ishida That is similar to the qual-
ilYlevel obtained by gears that have been cut and shaved or bur-nished Ishida says
Createch ha created what Ishida refers to as a dialog withmold meaning thai the interaction between the die and theforged materials i so well unde load and controlled if as ifthe mold is speaking with the material I hida says This dia-
log allows a homogeneous distribution of inner suesse in ttie
finished part he addsAccording to Ishida the secret to creating crowned teeth is
radial force With a conventional forging die the material isforced into the mold with axial force Essentially the work
material i pre sed through ahelical die from one end Createchuses a conventional forgLng process ro create rougb helical gearswitholll crowning However becau e crowned teeth are thicker
in the middle than at the end they cannot be formed by uch aproces nor could they be easily removed from the die
To finish the gears the Created die els include a lapered die
Die E
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
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CliRClE 144
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Remove nicks burrs hear IffNJtscaleand Improve gear tooth sul1sce
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pawerlrllnsmlssoncom wwwgesrtchnoagycam GEAR TECHNOLOGY JANUARYFEBRUARY 2002 391
CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
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We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
Gleason Pfallteramp Gleason Phoenix
Liebherr Klingelnbergl- Oerlikon-Opal Hoeflerbull Hun_hbull Kapp-Niles SamputensilimiddotIMikmn-IMaagtsellel
We offer eur customelS Highest Accuracy Fas1est IDelivery
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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RapidDelivery
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
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Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
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GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
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machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
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wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
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wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
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Midwest Gear Corp2182 IEAurora Rd
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IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
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Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
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bull Wormlbull SpurI Helical
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CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
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CIRCLE 107
ALTE RNATIVE GEAR IMANUIFACTURING _
overseas marketing and planning for Shin-KobeThe gears were developed in cooperation with Toyota Motor
Corp and are being used in the four-cylinder engines of theEstima Harrier Kluger Ipusarn and Camry models of Toyota
vehicles according 0 Tazawa The company expects total sales
of the gears to reach 3 billion yen (roughly $24 million) in 2002The new gears are made of KOBE LlTEreg KM-9000 an
aramid-reinforced fiber and polyaminoamide resin resulting inincreased durability and heat resistance when compared to con-ventional plastic gears such as phenolic resin with glass fibersThe gears also significantly reduce noise when compared with
metal gears previou Iy used At 2000 rpm the noise can bereduced by at least 15 decibels Tazawa says
Shin-Kobe uses a special spun yarn to improve the adhesionof the aramid fiber which normally doesnt have a good affini-ty with resin Tazawa says The fibers are arranged so that theyradiate from the center of the gear giving the gear added
strength Aramid also is less damaging to the mating gear teeththan glass or carbon fibers would be
In addition the plastic gears allowed designers to eliminate
backlash shims which were required with metal gears previously
used This saves assembly labor and complexity Tazawa saysCircle 3]7
IGear Parts Win iin PMllCompetitionEach year the Metal Powder Industries Federation (MPIF)
holds a design competition to highlight the best uses of powdermetal technology The 200 I awards included many gears andgear-related items among the winners
The Ferrous Grand Prize went to Stackpole Ltd of Stratford
Ontario Canada for an intricate planetary gear carrier assemblymade for GM Powertrain
Nonferrous GrandiPrize Precision Powdered Metal PartsThe carrier assembly replaces a cast Iron carrier in GMs PT
4L60E heavy-duty transmission which is used in 800 series
vehicles inc1udingthe Sierra Silverado Suburban Escaladeand Corvette
The assembly consists of a low-alloy steel spider and copper-steel clutch hub which are sinter-brazed together into one unit
The multifunctional assembly combines the planetary carrierand cfuteh hub functions afirst for Stackpole The new assem-bly reduces machining reduces the parts weight and increasesdurability without secondary heat treatment of the splines
The Nonferrous Grand Prize also went to companies work-
ing with gears Eight nickel-silver parts including five gearswon that prize The parts were made by Precision Powdered
Metal Parts of Pomona CA for a three-fold fire alarm box man-ufactured by Gamewell Worldwide of Ashland MA
Previously these parts were manufactured by stamping andmachining but the manufacturer was able to reduce costs by50 after switching to powder metal manufacturing
c IBevel1gear indexing ratchets 1iransmission eanier byFerrous GrandiPme Stackpole Itd IbyAllied Sin1erings Inc Keystone Powdered Metal Co38 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgearlecnngycom bull wWWpowBftransmlssloncom
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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For addmanar tnlarmaltan on itiIlll~ andoT tluJctfOllgl QUI
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CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
I
onmMilRoo bullbull Warren MI middot1109
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bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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We offer eur customelS Highest Accuracy Fas1est IDelivery
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
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CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
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lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
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MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
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Contact us todayto ~indout what we can do for YOli
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CIRCLE 107
_ bullbull _AlTiERNATIVE IGEARMANIUFAICTURING_
Other gear-related partsthat won awards were an automotive
manual transmission synchronizer ring made by SinterstahlGmbH of Fussen Gennany a counter-shaft transmission hub
with external involute spline teeth made by Caterpillar IncsAdvanced Compacting Technology Group of Rockwood TN atransmi sion carrier made by Keystone Powdered Metal Co ofSa Marys PA at bevel gearindexing rajchet for at surgical sta-
pler made by Allied Sinterings Inc of Danbury CTand a ratch-
et gear a embly for at cordless drill made by Jenn eng
Industrial oi Taiwan ROCThe annual design competition has awards for different care-
gories of parts The categoriesare injection-molded productsferrou (iron steel or iron-based ) nonferrous (copper copper-based bronze bra s nickel-silver or aluminum) advanced par-
ticulate materials stainless steel and other high alloys (less than50 iron) The organization also pre ents an overseas award
which is open to all material Parts are reviewed by a panel of judges appointed by the
MPIFsindusrry develcpment board and the criteria for awards
are design configuration engineering properties and promotion-al value
The competition is open to MPIlF member companies anddetailed rule can be obtained from MPlF by ending an e-mailmessage to infompiforg
CilCJe 318
CuTenI MIIgIWIc FkPQlbgnlllie~
Magnetic Compaction of IPowdered MetailAP Research Inc of Dayton OH has a process that uses
magnetic forces 110 fonn highly dense parts from powderedmetal materials Those parts may soon include autom tive trans-
mission ring gears[AP has been working with a major US automotive manu-
facturer to adapt the process called dynamic magnetic com-paction (DM ) to produce the ring gears Development testinghas shown thai the gears can be manufacturedtn AGMA 9 quali-ty with material den ity of 76 gcm) in the gear tooth area and
material properties approaching tho e of machined part says EdKnoth senior research engineer for lAP Although the parts meetdesign parameters ~hey need extensive laboratory testing to deter-mine long-Ierm fatigue life and other propesties Knoth says
GROUNDI GEARS - ren or ren ThousandFor small to medium quantities of spurs or helicals thaI have tomeet close-tolerance AGMA or DIN specs our Hsishausr grindersand MampM gear analysis systems arethe perfect combination
For Long runs we offer the unique Liebherr CBN grin dingprocess with full 5PC quality control and documentation
50 whether your needs are lor len or tens 01thousands weinvite you to join the growing list of INSCO customers who rely onus for consistent quality reasonable costs and reliable delivery
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Remove nicks burrs hear IffNJtscaleand Improve gear tooth sul1sce
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~UN_U8Pht3l~- 32OI1IM2ID
Err-aII ~~
pawerlrllnsmlssoncom wwwgesrtchnoagycam GEAR TECHNOLOGY JANUARYFEBRUARY 2002 391
CIRCLE 124
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
I
onmMilRoo bullbull Warren MI middot1109
CONTACTCRAIG 1)1RGSS(586) 754middot8923
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
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401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
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peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
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cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
CIRCLE 156
SPIRAL BEVEL GEARS(Transmissi ODS
Spiral amp Straight Bevel Gen ManufacturingCommercial to aircraft Iqualilygearing
Spur helical splined shafts internal amp externall
shaved amp groundl goalS Spirall bevel grinding Midwestlransmissions amp Reducers
ISO compliant
MIDWEST GEAR~MI - -81 TOOL IINC - -- rE~
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onmMilRoo bullbull Warren MI middot1109
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CIRCLE 1168
bullbull ALTERNATIVE GEARMANUFACTURIINIG-
A container 8ndidiie for making linternal ring gears by magneticcompaction of powdered metal
According to Knoth DMC also i capable of manufacturingother parts with ring-type geometriesand radially ymmetricfeatures The process is targeted for parts requiring high densityand material properties traditionally as oeiated with wrought
metals Knoth is confident that the process is a viable alternativefor many manufacturers I think its ripe for production he
say bull adding that the company is quoting jobs to u ethe processWith the DMC process the powdered metal is loaded into an
electrically conductive container or ring gears the center ofthe container i acore tool with me negativepattem of me gearteeth pound0 be formed Outside the core tool i a ring made of elec-trically conductive material End caps do e off the faces of thecontainer When the container is placed within aninduction coil
the magnetic field forces the outer ring to accelerate at rl1e rateof several hundred meters per second toward the core tool com-
pactmgthe powder in between The ring also decelerates quick-ly causing a high pressure spike in the powder which wveslibematerialit high den ity Knoth says
The process is capable of pressing steel powder to 96 of
full density according to lAP literatureCircle 3W9
Tall Us What YOUI Think
If you found this article of interest andor useful please cirela 309
If you did not care for this article circle 310
If you would like to respond to this or any other article in this edi-tion of Gear Technology please fal( your response to the attention ofRandy Stott managing editor at 847-437-6618 or send e-mail messagesto peoplegeartechnologvcom
4111 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY WWg68ftecllflologycom bull wwwpOW8lrSflsmlssioflcom
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
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Liebherr Klingelnbergl- Oerlikon-Opal Hoeflerbull Hun_hbull Kapp-Niles SamputensilimiddotIMikmn-IMaagtsellel
We offer eur customelS Highest Accuracy Fas1est IDelivery
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Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
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email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
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LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
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1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
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lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
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IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
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847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
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Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
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Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
_------------INDUSTRYNEWS------------ UOM Technologies To Exit Gear
Contract Manutacturing BusinessUQM Technologies Inc announced it
will exit the gear contract manufacturingbusiness because of weak demand forgears in the agricultural and over-the-road truck markets which the companyhas served
In its press release UQM said it plans10 seek buyers for its gear business or-if no buyers are found-s-sell its gearmanufacturing assets and stop opera-lions UQMs gear operations had annu-811 revenue of $]6 million for the fiscalyear that ended March 31 200 I and a(let loss of $1 I million
The revenue represents 6 percent ofannual consolidated revenue The lossrepresents 45 percent of consolidatedoperating los es before items
Our gearing operation has not metourexpectations due to continuing weak-ness in the industry generally and specif-ically in the markets we serve saidWilliam G Rankin UQMs presidentand CEO The outlook for recovery isriot promising a more and more gearpurchasers source their gearing require-ments overseas
Continued weak demand and theresulting poor financial performance ofthis operation has been a continuing drag011 consolidated financial performancefor the Iast couple of years and poorindustry fundamentals and the resultinggrim prospects for near-term recoveryhave led us to the decision to shed thisnon-core operation
Rankin added UQM is receivingincreasing demand for its motor genera-tor and power electronic products
Also Rankin said UQM will continueto produce and supply gears to customersand will consider gear orders from newcustomers until it seUs the business orstops operations He explained that if thebusiness were sold remaining orderswould be completed by the new owner
Lapointe IBu-ysOswald IForstLapointe International Corp bought
Oswald Forst GmbH amp Co KG ofSolingen Germany Forst Broach Ltd ofLeicester England and Cardinal BroachPic of Biggleswade and Ratby England
FarSI provideslrJelical broaching
machines Also Forst designs and manu-factures other broaching machines toolsand broach sharpeners for auto industryproducers and suppliers CardinalBroach PIc designs and manufacturesbroaching machines and tooling for theautomotive and turbine industries
In its press release Lapointe saidForsts helical broaching machineswould give Lapointe an important new
product line to offer to its customersLapointe International Corp of
Worcester MA design and manufac-tures machines and tooling for indu triesthat produce precision forms such ashelical gear rurbine disks and rifled gunbarrels The industries include automo-tive jet engine and land-turbine manu-facturing 0
precisian Ihrough diamond
INNOVATIVE PCD REINFORCINGFOR DIIRECT PlATED DRESSERS
We will design build and guarantee from your gear summary charts gear dressers forReishauer SPA and Fassler DSA Systems --DirectmiddotPlatedor Sintered-Bond Single- orDouble-Sided Dressers
WE also producegear dressers forIt Gleason lAG
Gleason Pfallteramp Gleason Phoenix
Liebherr Klingelnbergl- Oerlikon-Opal Hoeflerbull Hun_hbull Kapp-Niles SamputensilimiddotIMikmn-IMaagtsellel
We offer eur customelS Highest Accuracy Fas1est IDelivery
bull Competitive Prices Relapamp Illeplating Service
Call or fax us your gear dresser requirementsYou will quickly discover what leading US gear producers have learned
DR KAIISER gear dressers are the best value availableDistributed by
SLMunsonamp Company
401 IHuger St Columbia SC 29201Phone 1-800-775-1390 Fax 11-BOH1294l507E-mail infaslmunsancam
wwwpowertransmS$joncom bull wwwgeartechnologycom GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 41CIRCLE 116
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
PreciseProfiles
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
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SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
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f b Ir II n II n v 0 n I n 0 u
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f h h
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
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48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
PRODUCTINEWS _
Gieasolfl Offers New MachineFor Bevel IGear Rolli Testing
Gleason Corp is offering a newmachine for roll testing spiral and hypoidbevel gear sets
In its press release Gleason said itsnew 600 HIT Turbo Tester performsfa ter C C-controlled roll testing ofthose gear ets
The tester can accommodate work-pieces with 600-mm diameters Be idesbasic pattern checking the 600 HTTtests for single-flank transmission errorand trucrure-borne noise for soft andhard parts
According to Gleason the roll testerhas a small-footprint ergonomic easy-to-lise design
For more infosmation visit GleasonCorps website at wwwgleasoncom
Circle 320
Textron Has New HeHcoidal GearGeometry in Gearmolors bullReducers
Textron Power Transmission has anew helicoidal gear geometry for itsSeries B Conex nA helicoidal right anglegearmotors and reducers
According to Textron the new geom-etry called Conextrade inside provideshigh capacity and efficiency The gear-motors and reducers have power capabil-ities up to 20 hp with a maximum torqueof 5000 lb-in They also have gearratios up to 601 in one stage
For more information vi it the com-panys website at wwwtexmmptcom
Circle 321
Samputensili Automates Bevel GearDebuning Chamfering
Sarnputensili has a new machine theS 4501750 DEC Gear Debur Cell thatautomates deburring and chamfering ofbevel gears
The cell uses a FANUC 6-axis servo-driven robot and a programmable con-troller The cell can be used to do top andbottom loath and root gear deburring andchamfering geometry
[11 its press release SU America ilncsaid the S 4501750 reduces the time andcost normally associated with mostdeburring operations It also said the cellprovides more precise consistent part-to-part accuracy
According to SU America the celleliminate the need to manually deburand chamfer gears
The cell is available in two sizes 2through-hole with 18 diameter and 4through-hole with 30 diameter
In North America for more Informs-tion contact SU America throughMaritage Inc of Rockford IL by tele-phone at (815) 484-9250 or by fax at(8IS) 484-9254
Circle 322
Kollene Adapts Ferri1icNitrocarburbing fm Better
Corrosion ResistanceKolene Corp has developed a varia-
tion of its Nu-Tride ferritie nitrocarburiz-ing proces to improve part corrosionresistance and give them a black lowRMS finish The variation called theQPQ process is used to finish automotive
I ~
gears ancl other parts such as hydraulicand pneumatic parts
According to Kolenes press releaseQPQ processing follows Nu-Tride proc-essing and further improves parts corro-sian resistance
For more information contact KoleneCorp of Detroit MI by telephone at(3 [3) 273-9220 or visit its website atwwwkotenecom
Circle 323
Gear Technoloyywelcomes your new prnd-uet announcements for gears gear drivesand products for designing manufacturinglandllestingl gears
Send yournew product releases toGear Technology14011IluntAvenueElk Grove VilHage It 160001FaxB47 middot431middot661 BE-moHpeoplegeanechnologycom
Tell Us What YouThink
If you found this column of interest andoruseful please cilcle 324
If you did not care for this column circle 325
If you would like to respond to this or anyother article in this edition of GeorTechnology please fax your response to theattention of Randy Stott managing editor at847-437-6618 or send e-mail messages to 1
peoplegeartechnalagycam
42 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgeamiddotrtechnologycom bull wwwpowetttsnsmiuioncom
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
PreciseProfiles
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
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h h f
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b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
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d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
bull bullbull _TECIHINICAL CALENDAR 1 bullbullbull _
Jan 29-Heat Treating amp Hardening of Gear Embassy
Suites Nashville-Airport Nashville T Program leaches basic
concepts of heat treatment and hardening of gears and alterna-tive methods Intended for people involved in heat treating qual-
ity control material development or industrial operations $445for SME members $495 for non-members For more informa-
tion contact Lynn Albertson senior program developer bytele-
phone at (80m 733-4763 or bye-mail message atalbelYfIsmeolg
Jan 3O-31-Basic Gear Manufacturing amp Design Embassy
Suites ashville-Airport Nashville TN Program providesbasic concepts of gear design and manufacturing proces e Program can be used by gear de igners and inspectors project
engineers and proce scontrol engineers and technicians $745for SME members 895 for non-members For more informa-
tion contact Lynn Alben on enior program developer at (800)733- 4763 or bye-mail at albelYIIsmeorg
Feb 4I-7-Falk School Gear amp Coupling Workshop FaIlesRenew Busine Unit New Berlin WI Provides hands-on
training to familiarize working maintenance mechanic withfield-practical factory-approved installation alignment mainte-
nance and failure analysis procedures Specific attention to pre-vemative maintenance and early-warning diagnostic proceduresfor all equipment $1495 Course presented throughout 2002
Other upcoming dales are Feb 18-21 March 41-7 and March[1-N For more information contact Falk Corp bye-mail atbstejljalkcorpcom
Feb 18-21-Ghason Corp Gear Fundamentals CourseGleason Cutting Tools Corp Loves Park IL Four-day programfor people who are new to gear-making and want ba ic under-standing of gear geometry nomenclature manufacturing andin pection $895 Course presented throughout 2002 Other
dates of course include April 15-18 and June 24-27 For moreinformatica call (8]5) 877-8900 or vi it wwwgleasoncom
Feb 20--23---Huidtrans Compomac Portello Hall MilanFairground Milan Italy International exposition featuring
fluid power and mechanical motion control component manu-facturers including hydraulic pneumatics electronicsrgearsactuators and motors Admis ion i free Contact the show or-ganizer Fiere amp Mestre Sr1 of Milan Italy by telephone al(39) 02-409493-1 by fax at (39) 02-409493-68 or bye-mail atpromomiddotftcfieremostreit
Tell Us What You Think If you found this column of interest andor useful please circle 330
If you did not care for this column circle 331
If you would like to respond to this or any other article in this editionof Gear Technology please fax your response to the attention ofRandy Stott managing editor at 847-437middot6618 or send e-mail mes-sages to peoplegeartechnologycom
wwpowerlransmissioncom wwwgslIrtechnotogycom bull GEAR TECHNOLOGY JANUARYFEBRUARY 2002 4J
bull New flowline production
Supplier to leadingaerospace manufacturers
Tolerances to AGMAClass 12
Design assistanceavailable
For mora information contact
Aero Gear Inc1050 Day IHill RCIWfndlor CT 06015Tel (860) 6SaG888IFax (e60)2~5-8514
1119--2CERTIFIED
AI9DDD Aero Gear Inc
email buygearsaerogearcom wwWaerogear com
CIRCLE 127
ISO 9001 Certified
TRANSMECANJCA
RapidDelivery
PreciseProfiles
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
LETTER TO THE EDnOR
make in a day The salesman is taught thaitime is money so he only calls Oil the pay-
ing customers the 20 that aCCOIJJtfor
80 of Ills business One solution taken
by some machine tool companies is to setup regional technical ales and servicecenters This is a way ofgetting their cus-
tomers to come to them for service and
technical help It allows them to maintainpersonal relation hips
[ recall telling one of my salesmen to
call on a particular client every Mondaymorning at the same time He objectedsaying mat they never bought anythingfrom him However he followed my
instructions On one occasionjhere wasa serious problem on the factory floor the
morning he madehis weekly call Hewas able to help them out and in tumthey became one of his best customersLucky maybe but it was the personal
calls that made the difference not thecomputer fax machine phone calls
direct mail or telemarketingIam sorryfor the lateness in respond-
ing to your editorial As you have proba-bly guessed Iam a retired machine tool
person formerly vice president of salesfor Waterbury Farrel Division of Textron(Jones amp Lamson turning machines
Cleveland hobbing machines WaterburyFarrel presses Thompson grinders JampLmetrology and JampL grinders)
Returning the Personal Touch to BusinessDear Editor
Your recent editorial Out of theCave which appeared in the Marchi
April 200 1 issue was one of the mosttimely and meaningful messages that hasappeared in a trade journal in a long time
Today as you stated the personal touchinbusiness has been replaced by faxmachine e-mail impersonal direct mail
cell phones Internet andor telernarket-ing The face-to-face sales contact of my
generation has been replaced by these so-called more efficient and less lime-con-suming ways of conducting business
Salespeople today are taught that timeis money to qualify a_naccount and to callahead to make an appointment It is mucheasier to say no to a salesperson over thephone than it is when he is in your lobbyI recall passing a small tool shop andquestioning the salesman Iwas with why
we werent stopping to call on the shopHe said he had called them and they werenot buying any new equipment We
slopped and called on the owner andlearned that they were consideringexpanding as they had just received a
large contract from an automotive suppli-er 1 doubt that we would have receivedthis information over the phone
People still buy from people Personalservice and interacting with manage-ment manufacturing and shop people ona face-to-face basis is still the most effec-tive way of doing business I wish I had
every order I lost because of personalreasons to someone who was closer tothe customer than I was
Very few salespeople today make coldcalls In my dayevery salesman was
required to make cold calls There is aplace for telemarketing and it can produceresults but mere is still a place today forcold calls They can be very productive
I also have a problem with cellphones and how they are used I was witha salesman who called a manufacturingengineer to ask for an appointment He
then called rum to tell him we were leav-
ing the office He calledagain to tell himwe were tied up in traffic and again to
tell him we were in the area He hadinterrupted the manufacturing engineerfour times-twice when the engineerwas in the shop-and when we arrivedwe received less than a warm welcomeWe havent learned how 10 use the toys
we have in the correct manner Trade shows provide a neutral ground
for personal interacting with potential
buyer However unfortunately sales-people on the floor are taught to qualify
tile individual They will ask if you spec-ify equipment how soon you plan to pur-chase a piece of equipment etc and ifthe answers are not positive you are notlikely to receive much time from thesalesperson I recalJ receiving a large
order from a manufacturing engineerWhen he gave me the order he saidYou probably dont remember me but Iwas that student with whom you took
time to show your machines at ruTSmany years ago He had graduated from
engineering school and was now in aposition to buy capital equipment
You are so right that today we focus onprojects meetings and quotas rather thanthe people who help us meet sales goals
and objectives We are driven by the bot-tom line and we forget thai service andpersonal contact are still the best and oldestmethods of dealing with our customers 1
had a standing rule that all proposals andquotations were to be hand deliveredThis
allowed us to look into the eyes of the man-ufacturing engineer or purchasing agent
and obtain an immediate reaction to the
quote It is impossible to get any feedbackfrom a proposal that has been mailed faxedor e-mailed without any personal contact
The unfortunate thing is thatthe cost ofhaving a salesperson on the road continueto increase In addition the congestedair-ways and highways reduce the number ofcalls and contacts that a salesperson can
Regards
Albert B Albrecht
Tell Us What You Think If you would like to respond to this or anyother article in this edition of GearTechnology please tax your response to theattention of Randy Stott managing editor at847-437middot6618
44 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY wwwgaartoOhnoiogycom bull wwwpowearansmissioncom
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
CIRCLE 122
o OU HAVENEXT COVER
re IOOII~ for hJgh-quaiity imagesof gears for wing Issues
MarchAprIl Heat Treating
MayJune Gear Design
JulyAugust Inspection
wwwpowerliltnsmissoncom wwwgesrrechnc)ogycom bull GEAR TECHNOLOGY JANUARYIFEBRUARY 2002 4-5
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
CLASSIFIEDS---
EBSITES- - --
--~--~-------------------=_~_-=-===-1
CIRCLE 160
WEBSITES
APPLIED PROCESSA laader in Ibe heat trelling indtlrtry lor more thanthree decades Applied Process RJld its affiliales II~all$lemperinUI technologies to prodllce llrongerlougher struclur than thllSs producedl with conven-lional hUIlrealments AU5tempering is an isolhermal haat trntmenl lppJ[ed 10 lerrou5 mile rials 10loIQ I wide fange of engineering challenge bull
For more infDrmation visit aur webs ite a1www8ppliedpIOCeSScom
CIRCLE 131
--------
wwwraycargearcomCIRCLE 181l
l-lELP WANTED
IPARKER INIDIJSTFlIES (long Island NewYork) seeks sales-oriented Engineer withsome knowledge of gear cutting tools andrelated products Good technical and commu-nication skills a mustReply in confidence With relevant informaJion 10
IGeorge A ParkerParker Iindustries IlncorpoJated
PO Box 465Bohemia New York 11716
FlARteR
-_ E- III~ __
Rat Line Classified l minimum $325 Additional lines $45 per line (8 lines per inch) Display Classified 3 minimum lX--$735 3X-$685
per insertion 6X-$645 per insertion Addiuonal per inch 1-$255 3X-$235 per insertion 6X-$225 per insertion Caor Classified Add 150
per insertion for color Gear Technology will set type to advertisers layout or design II classified ad at no exira charge Payment Full payment must
accompany cla sified ads Send check drawn in US funds on a US bank or VisalMIl~erCrudlAmcricanExpress number and expiration dale 10Gear
Technology Po Box 1426 Elk Grove VillageJl 6OOCl9Agency Commission No agency commi sian on classified ads Materials Deodlille Ads
must be received by the 15th of the month two months prior to publication Acceptance Publisher reserves the right LO accept or reject advertisements
at hi discretion46 JANUARYFEBRUARY 2002 bull GEAR TECHNOLOGY bull wwwgllarlechnorogycommiddotmiddotwWIIIpOW9rrransmssoncom
~------------- -~-II- bullbull
GLEASON CORPORATION(ika11 i the 1orld 11101 COl1lprdl~lhl
rllln l()J fcar IlKlillILILlllllllf TllIlolmiddotlt~W oltcr a cornprchcn-ivlaquo ~Lar llIlIlIl~
machine pfOltralll for LC]) ~Lar Iltlhhlll~
milling and ~lilldilT~ npplicuion Ill L) lin-dnal IIlJ 1gt11 ltal 1lt lcuu 1110[lthlIl
our Irodlll1 and en i or 10 lind JC
lllll1 information c L1111 ill
wwwgieasoncomCIRCLE 162
SOFTWARE
CAJCULATION IPROGRAM FOR GEA_RBOXESKISSSIIh lSI ComprehRSIH suo 01 caleuttian progrllnadnigned 10enhance speed ad IGCulltr When designingcommon IIchine elements (Gelrs Shills J
KISSoh lutomates Ih design through optimizalion rou-tines The calculation methods arbull accDrding IJI inlammiddotliolilly recoglized uaJldards IAGMAISD DIN 1 aLI
To request more infomation on this product pla e COR-
lIet
1M Schroder 156 Carlllln IDrive IMIIOrelvllle Ne 21117(11)4) 528-1509or infokiss-sohCOIII
CIRCLE 136
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
I - --
I~am the SlJuroe dqualitygears From desIgn to
marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
- ------ ----
SERVICE I-- --
I HiQB SHARIPIENINIGS EIRVIICE
Stsr Eutter Co
I IFJiar7TSTAR UTIER COMPANY Iamp_ 1amp0-9001 CERTIFIED
bull THIN ~ILIM COATINGSWest Branch Industries
Subsidiary of Star Cutter Co2083 W Mmiddot55 West Branch MI48661
lmiddot88amiddotResharp bull middot811l1middot737-4277IPhone (989)345-2865 FAX 1989) 345-15660
CIRCLE 142
l--lINTER Sf ATE TDlOl CORP
CLEVE~ OHIIOI
CUSTOM ENGINEERED ampMANUFA CTURfD CUTTING TOOLS
ESTABLISHED 1960
FORM REUEVED amp PRIIRLE GROIlNDMIWNG CUTTERS
GEAR SHAPER amp SHAVING CunERSALL CLASSES OF HOBS
HSS saun CARBIDE amp CARBIDE TIPPED
WHETHER YOU EED NEW TOOLSMODIFICATIONS RESHARPENINGREPAIRS OR MampM INSPECTIONS
CONTACT US FOR A QUOtE rODAYI
wwwnterslafetootcorcomTel~ 216-611-1017 bull Fax 216-611-5431
CIRCLE151
GEAR TOOTIH GRINIDllNGiSpur Iielical
-IHerringbone (with groove)ICapacity upto IS 1001
1 DPbull 16M faca
AGMA CertificationllnspectionIDeliverytD Meet Your Requirements
Midwest Gear Corp2182 IEAurora Rd
Twinsburg OH 44087Phone 33O-425-4419Fax330-425-B600
IDirect your inquilies tDRon Humphrey General Manager
l~onhmwgeaFcom
OIRCLE 1154
10 pO9tlrnsmissJoncom bull wwwglilurschnologycom bull GEAR TECHNOLOGYmiddot JANUARYFEBRUARY 2002 JCiIRCLE 131
lnduetien HalrdelnlinlgSpeciallists in Tooth by Touth -IContour Hardeniing o lnterml11Spur helical and lJerveearsGur gear hardening equipmentincludes S NAlCO submergedprocess machines and 5 AJAXCNC-contwUed glear scanningmachines Tooth by tooth gearhardening from 5DP-10D~ up to15 tons 200 diameter
American Metall Trea1ing ICompanyCIavelandlbull Illllio
Pholle 1216) l31-449~middotFall 2U) 43~-1508Wemiddot wwwll11llricllamelBlrrrflatiag bullcom
IE-imailmarlritllmericaamstltrBlillg com
IBreakdoWlIl Servic8 Available
HOB SHIAIRPEINIINGI(7i63)1 425-5241 tHIN FILM COATINGS
iSS amp Carbide up to 5 lOiaStraight Gash
Sharpened amp InspectedPer AGMA STANDARDS
auick Turnaround
i I~QIJTHFIa~
KORO SHA_RPENING SERVICE9530middotmiddotmiddot 85TH AVENUE NO
MAPLE GROVE MN 55369CIRCLE 163
13511Windsor RoadLoves PIlJkIL 611111 USA
IPhone Smiddot1S-Sn-8900Fax 815-817-0264
Website wwwgleasoncomIE-Mail middot9ctcgleasoncom
CIRCLE 147
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marrufacwre bullbull to iIeIJIeI)COUllrm
Okamoto Uachlll6lJfer YOUl demsmNngpmislollg Inri II1latea PJMI
lIaIwnlsslDn prOductsLook to l1 middotfor 1M 11__ 1
Pntclmiddotllon0_ bull Spiral Bevel
bull Wormlbull SpurI Helical
bull SplinesCullom dagll6Mlce
HigJ ptotIucflotl captbfJiIyUlJlIllItclwd ql1Blily MYIcIII supplaquot
elIudarlOlumola achlneq
847520-7700 alit IdwwwakmatHQijJcQJp
CIRCLE 153
IGEAR TIOOTiHGRINDING SiERVICESSpur - Helical - OoubleHelical
Capacity up to 6Q11) 011 1 DP 2S
I
Stroke All ground gears certified up toAGMA Class 14+ on Zeiss-Hofler 11602CMM Inventory of grinders melucesHofler BOOHofler 1253 Supra Hofler 11500two Hofler Naval eNC Uloos (FlJlly CNCwith all-board CMM checkerjl and
I Hofler Rapid 1~ FormGrillder
I(i~elterGeaftech2530 Garrow St Houstcn TX 17003Phone 713-237middot917~3Fax 713-237middot12091
I Contact Mr Willie WhittingtonVisit our Website atwwwkreitermiddotgeanechcom
CIRCLE 141- - - - --
HIOB SHARIPENING i
Koepfer America LLC635 Schneider DriveSouth Elgin IL 60171Phone 847-9311-4121Fax 847-9311-4192
0 Statemiddotof-the-art CNCsharpeningand inspection machines
Wet grinding with free-cutting CBNordiamond wheels for ~Burn free sharp-ening of carbide or high speedisteel
bull Optional recoating and stripping
Rush service available
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
------ADDENiDUM _
addendumapexbacklashbeve~concentricitydedendumleccentricityfatiguegearsgrinding
gerrGeargeerrdwerdWorddiSearchsearsh
Find the gear-rellated words listed on the right in the puzzle below The words may be non-zontal vertical or diagonal and may be written forward or backward
I
I S 8 f 9 e n II I p s P II r a I e I
I I1 a t h 9i e a r s p 8 X e v e e xI
I h b
k d f te 9 0 Y u m I m y cy a f a b e d e n d u t v e I wt
f b Ir II n II n v 0 n I n 0 u
I kI r II p P I n 9 e Y c s e w
h I dC 91 n I n 01 n 18 n I e c e
f h h
I 9 u J n 9 n a r p I C ak t f tr a c e u s I a I p n r
I
I
t b II
h h f
Y n JI 9 9 n 9 9 II C
b d
d d d fn I I X n r 8 r u u1 h
h
h Ie w J c gl e II u 8 c r s nc r t t a n s d p r r n 8 e e dc 0 0 p I Ih n s t a n 0 e t r 8
b
d h e 0 n I II J e u c c u r rt b t h k Ih b I Ir n n v m u I C
d
f In a n g u II I W U I 0 n ue c e f v 9 t 0 h d m k 0 v 9 t
I
k t t b t I
I
c c P II I n gl a c v nI b b I b
c w 0 e n v u n II 01 P
d b fI e a 0 n y n n n a p II S nc s r II t e m u d n e d d a 18 I
h d d
hc m 01 J u 0 I 0 P Y I nI
48 JANUARYFEBRUARY 2002 GEAR TECHNOLOGY wwwgBalechnoiogycom wwwpowBrlransmissioncom
honinghelicalherringbonehobbinglh aid_ypOLinvolutepiinlionpittingrackrippling
skewspiraispUnespurtilptoothundercutwearwormwobblle
A very exceUentgear wordlbull
Tell Us WhatYou Think If you found this article ofinterest andor uselulplease circle 340IIyou did not care for thisarticle circle 341
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
e cat IJn a Aour pe8rn~eqaT~e nlen()Y o~ satQaTd and non-sand8rd cu~n~ ~oos
f eaTSo~ eXgeenoe manut8cun~ arcrM pars compe~et1Temesno ead-~mQson ~o~opeand custom jobs
)01Qns o~ locessn~ ses wnn drlVinamp distance~uo-oaded CtlC hoboni and turnna equipmentC~C ~ea and tlnQsha~na up 441 dlameter
c~c utlna Ull 0 30 damee by 2011 tong~ou-axsmlnA up 0 3SIf 8811 onamp~Xle ~ea and spne enampneering staHManAaca~ OpoundM QuatA approvals
oner CNC ~e8 nspeclon-N eXlerenced
Perry Technology CorporatioPo Box 21I 29 Indusrial Park Road
New Hartford T 06057Phone ~860~738-2525
CIRCLE 134 Fax (860)1738-2455E~~a~ sa1esperrygearcornVcbsle www er geareo
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107
Samputensili presents the new modularS-series in a complete diameter rangefrom 100 up to 3000 mm built inChemnitzlGermany the cradle ot gearnobbing -
In addition we provide an unmatchedservice and sales network throughoutthe US by Meritage National Servicesand its aHiliates
SU America Inc8775 Capital AveOak Park Mil 48237leI -1-1248548-7171Fax +1248 548-4443E-mail salessuamericacomhttpwwwsamputensilicomWith this recent addition to our machine
1001 line we are able to offer you completesolutions for your gear cutting needs fromroughing to finishing
Contact us todayto ~indout what we can do for YOli
IS 11cer11lied
~QS--Tl
cerrifieci
Bevel Gear Cutting - Tool and Commodity Management Services (eMS)
CIRCLE 107