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CONTENTS

INFORMATION OF THE COMPANY.2

NUMBER OF EMPLOYEES..3

SKETCH OF THE ORGANIZATION..5

COST ANALYSE.6

INTRODUCTION6

CASTING OF METALS.7

WELDING1

!A"# $%&'()*..12

!I)%"+ *,- $%&'()*.1

HEAT TREATMENT.16

!S/0+%)()*..17

!H,"'%)()*2

!F/"*()*.2

TURNING.26

MILLING..32

DRILLING35

GRINDING...3

PRESSWORKING...3

CNC MACHINES1

CONCLUSION.2

1

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INFORMATION OF THE COMPANY

C/4,) ),% Kayacan malat ve Kalp Sanayi Ltd. ti.

L/#,+(/) 690. Sokak No: 41 vedik Orani!e Sanayi "enima#alle$%NK%&%

Kayacan 'a( )o*nded in 199+ ,y -an O%N and /(eyin K%&%K%"% '#o are (tillt#e mem,er( o) t#e manaement o) t#e company. #e p*rpo(e o) t#e )o*ndation 'a( to prod*ce t#etractor part( )or 2 3 rk raktr 2a,rika( 5. #ey #ad (i vario*( 'ork,enc#e( and nat*rally t#e

prod*ction 'a( limited. 7*t no' t#ey #ave +6 'ork,enc#e( (*c# a( drill8 lat#e8 millin mac#ine etc.

and t#ey try to increa(e t#e n*m,er o) t#em.

ean'#ile -an O%N )a,ricated #i( (pecial mac#ine '#ic# i( called am,*r; ,y t#eemployee( and t#ey *(ed it to o,tain t#e (moot# (*r)ace o) t#e part(.

No'aday( company (till prod*ce( t#e tractor part( 3< =>5 )or t#e rk raktr 2a,rika( ? 2iat-orporation and t#e re(t )or t#e di))erent companie( (*c# a( @rk*nt.

%ll o) t#e employee( in Kayacan #ave eno*# in)ormation a,o*t tec#nical dra'inA t#ey #ave totake le((on( in t#e company time ,y time. @very proce(( i( (*pported ,y t#e B*ality control manaer'it# t#e iven operation pae( '#ic# are incl*ded t#e dra'in and t#e vario*( in)ormation a,o*t t#eoperation. Ci(tri,*tor (*pport8 dry air )ilter (*pport8 (ealed oil level rod a((em,ly8 ca, r*,,er mo*nt(n*, *pper 'a(#er8 )ied #ine8 #and ,rake ('itc# mo*ntin plate8 additional 'a(#er are t#e eample(o) t#e prod*ced part(.

TAMBUR8

D

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T9% N:;%" O0 E4&/%%- I) K,,#,)

anaerEEEEEEED

F*ality -ontrolEEEE.1

2oremanEEEEEEE1

CriverEEEEEEEE1

Geldin a(terEEEE.+

Hre(( a(terEEEEE..4

Lat#e a(terEEEEE.1

-ookEEEEEEEE.1

F/&&/$()*- ,"% +9% %

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H,)' B",=% S$(+#9 M/:)+()* P&,+%

It #a( ,een prod*ced )or rk raktr 2a,rika( ,y Kayacan.

In t#e con(tr*ction p#a(e o) t#e #and ,rake ('itc# mo*ntin plate )rament8 t#e )ir(t operationi( t#e c*ttin o) t#e ,end 'it# t#e *illotine. In t#e pre(( mac#ine t#e eterior circ*m)erence i( (liced*p. %)ter t#at operation t'o #ole( are ,ored and it( ,order( are c*lled. %)ter t#e moment it( c#ip i(taken in tam,*r8 'it# t#e #ead o) t#e drill8 metric )or matc#maker i( applied. In t#e la(t (tae o) t#e

prod*ction8 ,y (endin t#e )rament( to t#e cro'n atelier8 t#ey are cro'n 'it# !inc. #e rea(on o) t#eoperation o) cro'nin 'it# !inc i( t#e corro(ion re(i(tance.

Z()#inc i( a (ilvery ,l*eJrey metal 'it# a relatively lo' meltin point 3419.>-5 and,oilin point 390-5. G#en *nalloyed8 it( (trent# and #ardne(( i( reater t#an t#at o) tin or lead8 ,*tapprecia,ly le(( t#an t#at o) al*min*m or copper. #e p*re metal cannot ,e *(ed in (tre((edapplication( d*e to lo' creepJre(i(tance. 2or t#e(e rea(on( mo(t *(e( o) !inc are a)ter alloyin 'it#(mall amo*nt( o) ot#er metal( or a( a protective coatin )or (teel. One o) t#e mo(t *(e)*lc#aracteri(tic( o) !inc i( it( re(i(tance to atmo(p#eric corro(ion8 and M*(t over #al) o) it( *(e i( )or t#e

protection o) (teel'ork.

4

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T9% -=%+#9 /0 +9% /"*,)(>,+(/)

>

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%verae epen(e val*e( o) Kayacan i( (#o'n ,elo'E3Salary val*e( are t#e total val*e( )or eac#rank5

COST ANALYSE

!anaer (alarie(: +000 "L

Ja(ter( (alarie( : 4=1> "L

J@lectric invoice : +>0 "L

JGater invoice : D=0 "L

J@ndor(ement : 1400 "L per day

J&entin pay : 1100 "L

JSSK payment : 1=6+ "L

!LiB*id )*el : 400 "L

JOt#er( : 1000 "L

JHro)it : < D0

INTRODUCTION

#e (*,Mect o) t#e (*mmer practice i( to make *( 'ellJin)ormed enineer candidate a,o*t t#eman*)act*rin proce((e(Jtec#niB*e( (*c# a( t*rnin8 millin8 rindin8 drillin etc. %l(o t#eeconomical analy!e )or t#e prod*ct and t#e e))ect( on t#e company.

2ir(tly8 t#i( trainin co*r(e i( very important )or me ,eca*(e it i( t#e )ir(t c#ance to (eeeveryt#in in real li)e. o et more in)ormation a,o*t t#e man*)act*rin proce((e( and improve mytalent(8 i #ave to do more practice and learn more and more. I ,elieve t#at t#e 'ay o) ,ein a ood

enineer (tart( in t#e atelier. S*mmer practice ive( *( a c#ance to apply o*r t#eoretical kno'ledeinto practice.

I #ad an eperience )rom @ 199 in t#e (c#ool and it #ad ,een very *(e)*l )or me and 'ill ,e.7*t @ D99 i( di))erent )rom @ 199 ,eca*(e t#e real li)e and it( condition i( #ard. No,ody (tr*leto teac# (omet#in to yo*8 (o yo* m*(t try to learn or a(k everyt#in. %ll o) t#e 'ork( o on 'it# t#e(trict r*le( and yo* dont #ave c#ance to do (omet#in 'ron8 ot#er'i(e yo* #ave (erio*( pro,lem(.

-on(eB*ently8 t#e (*mmer practice incl*ded a lot o) ,ene)icial in)ormation and o,(ervation8 (o'e m*(t *tili!e it to prepare *( )or t#e real li)e.

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CASTING OF METALS

olten metal( are (#aped ,y po*rin 3ca(tin5 into a mold o) t#e reB*ired )orm8 '#ic# t#eyenter *nder ravity8 centri)*al )orce8 or vario*( deree( o) pre((*re. old( are made o) re)ractorymaterial( like (and8 pla(ter8 rap#ite8 or metal. Sand mold( are )ormed aro*nd a pattern or replica o)t#e part to ,e made8 *(*ally o) 'ood t#o*# pla(tic( or metal may ,e *(ed '#en lare n*m,er( o)mold( )or (imilar part( are to ,e made.

G"%%)!-,)' /&'()*i( *(ed )or mo(t (and ca(tin(8 (and mied 'it# a ,inder ,ein packedaro*nd t#e pattern ,y #and8 'it# po'er tool(8 or in a vi,ratin mac#ine '#ic# may al(o eert acompre((ive )orce to pack t#e rain( more clo(ely. #e term reenJ(and; implie( t#at t#e ,inder i(not c*red ,y #eatin or c#emical reaction(. #e pattern i( made in t'o #alve(8; '#ic# *(*ally areattac#ed to oppo(ite (ide( o) a )lat plate. S#aped ,ar( and ot#er proMection( are )a(tened to t#e plate to)orm connectin c#annel( and )*nnel( in t#e (and )or entry o) t#e molten metal into t#e ca(tincavitie(. #e (and i( (*pported at t#e plate ede( ,y a ,oJ(#aped )rame or )la(k8 'it# locatin ta,(t#at alin t#e t'o mold #alve( '#en t#ey are later a((em,led )or t#e po*rin operation.

/ollo'( and *nderc*t (*r)ace( in t#e ca(tin are prod*ced ,y core(8 al(o made )rom (and8 t#at

are placed in po(ition ,e)ore t#e mold i( clo(ed8 and #eld in place ,y tenon( in roove( 3called print(5)ormed in t#e (and ,y pattern proMection(. %n *nderc*t (*r)acei( one )rom '#ic# t#e pattern cannot ,e'it#dra'n in a (trai#t line8 (o m*(t ,e )ormed ,y a core in t#e mold. G#en t#e po*red metal #a((olidi)ied8 t#e )rame i( removed and t#e (and )all( or i( cleaned o))8 leavin t#e )ini(#ed ca(tin readyto ,e c*t )rom t#e r*nner(.

ray ironi( ea(ily ca(t in comple (#ape( in reenJ(and and ot#er mold( and can ,e mac#inedreadily. #e iron *(*ally contain( car,on8 1.?4.>8 and (ilicon8 1?+ per cent ,y 'ei#t. @ce(( car,onin t#e )orm o) rap#ite )lake( prod*ce( t#e ray (*r)ace )rom '#ic# t#e name i( derived8 '#en aca(tin i( )ract*red.

S9%&& /&'()*invented ,y a erman enineer8 -ronin8 *(e( a re(in ,inder to lock t#e rain(o) (and in a 1P4J to +P=Jin.Jt#ick layer o) (and$re(in mit*re8 '#ic# ad#ere( to a #eated pattern plate

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a)ter t#e ma(( o) t#e mit*re #a( ,een d*mped ,ack into t#e container. #e #ot re(in B*ickly #arden(eno*# to make t#e (#ell t#*( )ormed (*))iciently riid to ,e removed )rom t#e pattern8 prod*cin a#al) mold. #e ot#er #al) mold i( prod*ced on anot#er plate ,y t#e (ame met#od. Hattern proMection()orm r*nner c#annel(8 ,a(in(8 core print(8 and locatin tenon( in eac# mold #al). -ore( are in(erted to)orm internal pa((ae( and *nderc*t(. #e (#ell a((em,ly i( placed in a moldin ,o and (*pported

'it# (ome ot#er material (*c# a( (teel (#ot or coar(e (and8 '#en t#e molten metal i( to ,e po*red in.Some (#ell mold( are (tron eno*# to ,e )illed 'it#o*t ,ack*p8 and t#e t'o mold #alve( are merelyclamped toet#er )or metal to ,e po*red in to make t#e ca(tin.

QJHroce(( i( a met#od '#ere,y dry8 *n,onded (and i( #eld to t#e (#ape o) a pattern ,y avac**m. #e pattern i( provided 'it# m*ltiple vent pa((ae( t#at terminate in vario*( po(ition( allover it( (*r)ace8 and are connected to a common plen*m c#am,er. % #eatJ(o)tened8 0.00D?0.00>Jin.Jt#ick pla(tic( )ilm i( draped over t#e pattern and a vac**m o) D00?400 mm o) merc*ry i( applied tot#e c#am,er8 (*ckin o*t t#e air ,eneat# t#e )ilm (o t#at t#e pla(tic( i( dra'n into clo(e contact 'it#t#e pattern. % (and ,o or )la(k 'it# 'all( t#at al(o contain #ollo' c#am,er( and a )lat rid t#at (pan(t#e central area i( placed on t#e pattern plate to con)ine t#e dry *n,onded (and t#at i( allo'ed to )all

t#ro*# t#e rid on to t#e pattern.

%)ter vi,ration to compact t#e (and aro*nd t#e pattern8 a )ormer i( *(ed to (#ape a (pr*e c*pinto t#e *pper (*r)ace o) t#e (and8 connectin 'it# a ri(er on t#e pattern8 and t#e top (*r)ace o) t#e(and i( covered 'it# a pla(tic( )ilm t#at etend( over t#e )la(k (ide(. #e #ollo' c#am,er( in t#e )la(k'all( are t#en connected to t#e vac**m (o*rce. #e vac**m i( (*))icient to #old t#e (and rain( int#eir packed condition ,et'een t#e pla(tic( )ilm( a,ove and ,eneat#8 )irmly in t#e (#ape de)ined ,y t#e

pattern8 (o t#at t#e )la(k and t#e (and #al) mold can ,e li)ted )rom t#e pattern plate. atc#in #al)mold( made ,y t#e(e proced*re( are a((em,led into a complete mold8 'it# core( in(erted i) needed.Git# ,ot# mold #alve( (till #eld ,y vac**m8 molten metal i( po*red t#ro*# t#e (pr*e c*p into t#emold8 t#e pla(tic( )ilm ,et'een t#e mold (*r)ace( ,ein melted and evaporated ,y t#e #ot metal. %)ter(olidi)ication8 t#e vac**m i( relea(ed and t#e (and8 toet#er 'it# t#e ca(tin8 )all( )rom t#e mold)la(k(. #e ca(tin( emere cleanly8 and t#e (and need( only to ,e cooled ,e)ore re*(e.

P%",)%)+ /&', or*",?(+ '(%8 ca(tini( mainly *(ed )or non)erro*( metal( and alloy(. #emold 3or die5 i( *(*ally iron or (teel8 or rap#ite8 and i( cooled ,y 'ater c#annel( or ,y air Met( on t#eo*ter (*r)ace(. -avity (*r)ace( in metal die( are coated 'it# a t#in layer o) #eatJre(i(tant material. #emold or die de(in i( *(*ally in t'o #alve(8 alt#o*# many m*ltipleJpart mold( are in *(e8 'it# loo(e(and or metal core( to )orm *nderc*t (*r)ace(. #e ca(t metal i( (imply po*red into a )*nnel )ormed int#e top o) t#e mold8 alt#o*# ela,orate tiltin mec#ani(m( are o)ten *(ed to control t#e pa((ae o)

metal into 3and emerence o) air )rom5 t#e remote portion( o) die cavitie(.

7eca*(e t#e die temperat*re varie( d*rin t#e ca(tin cycle8 it( dimen(ion( varycorre(pondinly. #e die i( opened and eMector( p*(# t#e ca(tin o*t a( (oon a( it( temperat*re i( lo'eno*# )or (*))icient (trent# to ,*ild *p. C*rin t#e period a)ter (olidi)ication and ,e)ore eMection8coolin contin*e( ,*t (#rinkae o) t#e ca(tin i( re(tricted ,y t#e die. #e alloy ,ein ca(t m*(t ,e(*))iciently d*ctile to accommodate t#e(e re(triction( 'it#o*t )ract*rin. %n alloy t#at tear( or (plit(d*rin coolin in t#e die i( (aid to ,e #ot (#ort and cannot ,e ca(t in riid mold(. Cimen(ion( o) t#eca(tin at (#op temperat*re( 'ill ,e related to t#e die temperat*re and t#e dimen(ion( at eMection.&*le( )or ca(tin (#rinkae t#at apply to )ria,le 3(and5 mold( do not #old )or riid mold(. Ce(iner( o)metal mold( and die( rely on temperat*reJ,a(ed calc*lation( and eperience in evolvin (#rinkae

allo'ance(.

=

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L/$!4"%--:"% #,-+()* *(e( mold or die de(in( (imilar to t#o(e )or ravity ca(tin. #econtainer 3cr*ci,le5 )or t#e molten metal #a( provi(ion )or an airti#t (eal 'it# t#e mold8 and '#en a(or air pre((*re 36?10 l,$in.D5 i( applied to t#e ,at# (*r)ace in(ide t#e cr*ci,le8 t#e metal i( )orced *p a#ollo' re)ractory t*,e 3(talk5 proMectin )rom t#e die *nder(ide. #i( (talk etend( ,elo' t#e ,at#level (o t#at metal enterin t#e die i( )ree )rom oide( and imp*ritie( )loatin on t#e (*r)ace. #e rate

o) )illin i( controlled (o t#at air can ,e epelled )rom t#e die ,y t#e enterin metal. Git# ood de(inand control8 #i#JB*ality8 nonporo*( ca(tin( are made ,y ,ot# ravity and lo'Jpre((*re met#od(8t#o*# t#e etra pre((*re in lo'Jpre((*re die ca(tin may increa(e t#e den(ity and improve t#ereprod*ction o) )ine detail in t#e die.

S@:%%>% #,-+()**(e( a metal die8 o) '#ic# one #al) i( clamped to t#e ,ed o) a lare 3*(*ally5#ydra*lic pre(( and t#e ot#er to t#e vertically movin ram o) t#e pre((. olten metal i( po*red into t#elo'er die and t#e *pper die i( ,ro*#t do'n *ntil t#e die i( clo(ed. #e amo*nt o) metal in t#e die i(controlled to prod*ce a (li#t over)lo' a( t#e die clo(e( to en(*re complete )illin o) t#e cavity. #e#eated die( are l*,ricated 'it# rap#ite and pre((*re( *p to D> ton( per (B*are inc# may ,e applied ,yt#e pre(( to (B*ee!e t#e molten metal into t#e tinie(t rece((e( in t#e die. G#en t#e pre(( i( opened8 t#e

(olidi)ied ca(tin i( p*(#ed o*t ,y eMector(.

F()(-9()* O4%",+(/)- 0/" C,-+()*-

&emoval o) ate( and &i(er( )rom -a(tin(J%)ter t#e molten iron or (teel #a( (olidi)ied andcooled8 t#e ca(tin( are removed )rom t#eir mold(8 eit#er man*ally or ,y placin t#em on vi,ratorymac#ine( and (#akin t#e (and loo(e )rom t#e ca(tin(. #e ate( and ri(er( t#at are not ,roken o)) int#e (#akeJo*t are removed ,y impact8 (a'in8 (#earin8 or ,*rninJo)) met#od(. In t#e impact met#od8a #ammer i( *(ed to knock o)) t#e ate( and ri(er(. G#ere t#e po((i,ility ei(t( t#at t#e )ract*re 'o*ldetend into t#e ca(tin it(el)8 t#e ate( or ri(er( are )ir(t notc#ed to a((*re )ract*re in t#e proper place.Some ri(er( #ave a neckedJdo'n (ection at '#ic# t#e ri(er ,reak( o)) '#en (tr*ck. Spr*eJc*ttermac#ine( are al(o *(ed to (#ear o)) ate(. #e(e mac#ine( )acilitate t#e removal o) a n*m,er o) (mallca(tin( )rom a central r*nner. 7and (a'(8 po'er (a'( and a,ra(ive c*tJo)) '#eel mac#ine( are al(o*(ed to remove ate( and ri(er(. #e *(e o) ,and (a'( permit( )ollo'in t#e conto*r o) t#e ca(tin'#en removin *n'anted appendae(. %,ra(ive c*tJo)) '#eel( are *(ed '#en t#e ca(tin( are too#ard or di))ic*lt to (a'. Oyacetylene c*ttin torc#e( are *(ed to c*t o)) ate( and ri(er( and to o*eo*t or remove (*r)ace de)ect( on ca(tin(. #e(e torc#e( are *(ed on (teel ca(tin( '#ere t#e ate( andri(er( are o) a relatively lare (i!e. S*r)ace de)ect( are (*,(eB*ently repaired ,y conventional 'eldinmet#od(.

%ny *n'anted material in t#e )orm o) )in(8 ate(8 and ri(er pad( t#at come a,ove t#e ca(tin(*r)ace8 c#aplet(8 partinJline )la(#8 etc.8 i( removed ,y c#ippin 'it# pne*matic #ammer(8 or ,yrindin 'it# (*c# eB*ipment a( )loor or ,enc#J(tand rinder(8 porta,le rinder(8 and ('inJ)ramerinder(.

B&,-+ C&%,)()* /0 C,-+()*-!7la(t cleanin o) ca(tin( i( per)ormed to remove ad#erin (and8to remove core(8 to improve t#e ca(tin appearance8 and to prepare t#e ca(tin( )or t#eir )inal )ini(#inoperation8 '#ic# incl*de( paintin8 mac#inin8 or a((em,lin. Scale prod*ced a( a re(*lt o) #eattreatin can al(o ,e removed. % variety o) mac#ine( are *(ed to #andle all (i!e( o) ca(tin. #emet#od( employed incl*de ,la(tin 'it# (and8 metal (#ot8 or ritA and #ydra*lic cleanin or t*m,lin.

In ,la(tin8 (#arp (and8 (#ot8 or rit i( carried ,y a (tream o) compre((ed air or 'ater or ,y centri)*al)orce 3ained a( a re(*lt o) '#irlin in a rapidly rotatin mac#ine5 and directed aain(t t#e ca(tin

9

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(*r)ace ,y mean( o) no!!le(. #e operation i( *(*ally per)ormed in ca,inet( or enclo(ed ,oot#(. In(ome (et*p( t#e ca(tin( are placed on a revolvin ta,le and t#e a,ra(ive )rom t#e no!!le( t#at areeit#er mec#anically or #andJ#eld i( directed aain(t all t#e ca(tin (*r)ace(. *m,lin mac#ine( areal(o employed )or cleanin8 t#e ca(tin( ,ein placed in lare revolvin dr*m( toet#er 'it# (l*(8

,all(8 pin(8 metal p*nc#in8 or (ome a,ra(ive8 (*c# a( (and(tone or ranite c#ip(8 (la8 (ilica8 (and8 or

p*mice. F*ite )reB*ently8 t#e t*m,lin and ,la(tin met#od( are *(ed toet#er8 t#e part( t#en ,eint*m,led and ,la(ted (im*ltaneo*(ly. -a(tin( may al(o ,e cleaned ,y #ydro,la(tin. #i( met#od *(e(a 'aterJti#t room in '#ic# a mit*reo) 'ater and (and *nder #i# pre((*re i( directed at t#e ca(tin( ,y mean( o) no!!le(. #e action o) t#e'ater and (and mit*re clean( t#e ca(tin( very e))ectively.

/eat reatment o) Steel -a(tin(JSteel ca(tin( can ,e #eat treated to ,rin a,o*t di))*(ion o)car,on or alloyin element(8 (o)tenin8 #ardenin8 (tre((Jrelievin8 to*#enin8 improvedmac#ina,ility8 increa(ed 'ear re(i(tance8 and removal o) #ydroen entrapped att#e (*r)ace o) t#eca(tin. /eat treatment o) (teel ca(tin( o) a iven compo(ition )ollo'( clo(ely t#at o) 'ro*#t (teel o)(imilar compo(ition.

E-+(,+()* C,-+()* W%(*9+!G#ere no pattern or die #a( yet ,een made8 a( '#en preparin aB*otation )or makin a ca(tin8 t#e 'ei#t o) a ca(t component can ,e e(timated 'it# )air acc*racy ,ycalc*latin t#e vol*me o) eac# o) t#e ca(tin )eat*re(8 (*c# a( ,oJ or rectan*larJ(ection )eat*re(8cylindrical ,o((e(8 #o*(in(8 ri,(8 and ot#er part(8 and addin t#em toet#er. Several comp*ter

proram(8 al(o mea(*rin mec#ani(m( t#at can ,e applied to a dra'in8 are availa,le to a((i(t 'it#t#e(e calc*lation(. G#en t#e vol*me o) metal #a( ,een determined it i( nece((ary only to m*ltiply ,yt#e *nit 'ei#t o) t#e alloy to ,e *(ed8 to arrive at t#e 'ei#t o) t#e )ini(#ed ca(tin. #e co(t o) t#emetal in t#e )ini(#ed ca(tin can t#en ,e e(timated ,y m*ltiplyin t#e 'ei#t in l, ,y t#e co(t$l, o) t#ealloy. %llo'ance( )or meltin lo((e(8 and )or t#e etra metal *(ed in ri(er( and r*nner(8 and t#eco(t o) meltin and mac#inin may al(o ,e added to t#e co(t$l,. @(timate( o) t#e co(t( o) patternJ ordieJmakin8 moldin8 po*rin and )ini(#in o) t#e ca(tin8 may al(o ,e added8 to complete t#eB*otation e(timate.

WELDING

W%&'()* i( t#e proce(( o) permanently Moinin t'o or more metal part(8 ,y meltin ,ot#material(. #e molten material( B*ickly cool8 and t#e t'o metal( are permanently ,onded. Spot'eldin and (eam 'eldin are t'o very pop*lar met#od( *(ed )or (#eet metal part(. Spot 'eldin i(

primarily *(ed )or Moinin part( t#at normally *p to + mm 30.1D> in5 t#ickne((. SpotJ'eld diameter(

rane )rom + mm to 1D.> mm 30.1D> to 0.> in5 in diameterM,+%"(,&-

Lo' car,on (teel i( mo(t (*ita,le )or (pot 'eldin. /i#er car,on content or alloy (teel( tend to)orm #ard 'eld( t#at are ,rittle and co*ld crack. #i( tendency can ,e red*ced ,y temperin.

%*(tenitic Stainle(( (teel( in t#e +00 (erie( can ,e (pot 'elded a( al(o t#e 2erritic (tainle(((teel(. arten(itic (tainle(( (teel( are not (*ita,le (ince t#ey are very #ard.

%l*min*m( can ,e 'elded *(in #i# po'er and very clean oide )ree (*r)ace(. -leanin t#e

(*r)ace to ,e oideJ)ree8 add( etra co(t( 3t#at can ,e avoided 'it# lo' car,on (teel5.

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Ci((imilar material( cannot ,e (pot 'elded d*e to di))erent melt propertie( and t#ermalcond*ctivitie(. Hlated (teel 'eldin take( on t#e c#aracteri(tic( o) t#e coatin. Nickel and c#rome

plated (teel( are relatively ea(y to (pot 'eld8 '#erea( al*min*m8 tin and !inc need (pecial preparationin#erent to t#e coatin metal(.

M,):0,#+:"()* C/)-('%",+(/)-

#ickne(( o) t#e part( to ,e 'elded (#o*ld ,e eB*al or t#e ratio o) t#ickne((e( (#o*ld ,e le((t#an +:1. Spacin o) 'eld( in. Geld to 'eld (pacin R 10 Stock t#ickne((

-enter o) 'eld to ede di(tance R D 'eld diameter8 minim*m.

Geld to )orm di(tance R 7end &adi*( 1 'eld diameter8 minim*m.

%deB*ate acce(( )or (pot 'eldin (#o*ld ,e con(idered. Small )lane( in T c#annel( )oreample may re(trict t#e electrode )rom enterin t#e part.

2lat (*r)ace( are ea(ier to (pot 'eld d*e to ea(y acce((. *ltiple ,end( impo(e acce((re(triction(8 and (pecial )it*re( may #ave to ,e de(ined to #andle t#e part(8 i) acce(( i( not a

pro,lem.

Hrior to )ini(#in8 t#e (pot 'eld( #ave to ,e (anded or ro*nd to ,lend t#e 'eld( 'it# t#e re(to) t#e (*r)ace. It i( ,e(t to c#oo(e t#e (ame (pot 'eld (i!e8 to minimi!e (et*p( and increa(e t#ro*#p*t.

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Hlatin o) (pot 'elded a((em,lie( can ca*(e pro,lem( '#en t#e (#eet metal i( overlapped. #i(can ca*(e platin (alt( to ,e trappedJreB*irin (pecial cleanin8 or potential lonJterm corro(ion

pro,lem(. 7y care)*lly de(inin t#e a((em,ly to allo' ea(y drainin o) platin (ol*tion( t#i( can ,eavoided.

#e matin part( can ,e (el)JMied )or ea(y location prior to 'eldin. #i( can ,e done ,ylancin one part and locatin in a corre(pondin (lot in t#e ot#er partA or ,y ,o(( type etr*(ion8 'eld

,*tton(8 in part locatin to a (lot in t#e ot#er. #i( type o) de(in can o)ten eliminate t#e need )oreternal )it*re(.

A"# W%&'()*

%rc 'eldin i( one o) (everal )*(ion proce((e( )or Moinin metal(. 7y applyin inten(e #eat8metal at t#e Moint ,et'een t'o part( i( melted and ca*(ed to intermi J directly8 or more commonly8

'it# an intermediate molten )iller metal. Tpon coolin and (olidi)ication8 a metall*rical ,ond i(created. Since t#e Moinin i( an intermit*re o) metal(8 t#e )inal 'eldment potentially #a( t#e (ame(trent# propertie( a( t#e metal o) t#e part(. #i( i( in (#arp contra(t to nonJ)*(ion proce((e( o) Moinin3i.e. (olderin8 ,ra!in etc.5 in '#ic# t#e mec#anical and p#y(ical propertie( o) t#e ,a(e material(cannot ,e d*plicated at t#e Moint.

In arc 'eldin8 t#e inten(e #eat needed to melt metal i( prod*ced ,y an electric arc. #e arc i()ormed ,et'een t#e act*al 'ork and an electrode 3(tick or 'ire5 t#at i( man*ally or mec#anically*ided alon t#e Moint. #e electrode can eit#er ,e a rod 'it# t#e p*rpo(e o) (imply carryin t#ec*rrent ,et'een t#e tip and t#e 'ork. Or8 it may ,e a (pecially prepared rod or 'ire t#at not onlycond*ct( t#e c*rrent ,*t al(o melt( and (*pplie( )iller metal to t#e Moint. o(t 'eldin in t#e

man*)act*re o) (teel prod*ct( *(e( t#e (econd type o) electrode.

#e ,a(ic arcJ'eldin circ*it

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B,-(# W%&'()* C("#:(+

%n %- or C- po'er (o*rce8 )itted 'it# '#atever control( may ,e needed8 i( connected ,y a'ork ca,le to t#e 'orkpiece and ,y a U#otU ca,le to an electrode #older o) (ome type8 '#ic# make( anelectrical contact 'it# t#e 'eldin electrode.

%n arc i( created acro(( t#e ap '#en t#e eneri!ed circ*it and t#e electrode tip to*c#e( t#e

'orkpiece and i( 'it#dra'n8 yet (till 'it# in clo(e contact.

#e arc prod*ce( a temperat*re o) a,o*t 6>00V2 at t#e tip. #i( #eat melt( ,ot# t#e ,a(e metaland t#e electrode8 prod*cin a pool o) molten metal (ometime( called a Ucrater.U #e crater (olidi)ie(

,e#ind t#e electrode a( it i( moved alon t#e Moint. #e re(*lt i( a )*(ion ,ond.

A"# S9(%&'()*

/o'ever8 Moinin metal( reB*ire( more t#an movin an electrode alon a Moint. etal( at #i#

temperat*re( tend to react c#emically 'it# element( in t#e air J oyen and nitroen. G#en metal int#e molten pool come( into contact 'it# air8 oide( and nitride( )orm '#ic# de(troy t#e (trent# andto*#ne(( o) t#e 'eld Moint. #ere)ore8 many arcJ'eldin proce((e( provide (ome mean( o) coverint#e arc and t#e molten pool 'it# a protective (#ield o) a(8 vapor8 or (la. #i( i( called arc (#ieldin.#i( (#ieldin prevent( or minimi!e( contact o) t#e molten metal 'it# air. S#ieldin al(o may improvet#e 'eld.

#i( (#o'( #o' t#e coatin on a coated 3(tick5 electrode provide( a a(eo*( (#ield aro*nd t#e arc anda (la coverin on t#e #ot 'eld depo(it.

#e etr*ded coverin on t#e )iller metal rod8 provide( a (#ieldin a( at t#e point o) contact'#ile t#e (la protect( t#e )re(# 'eld )rom t#e air.

#e arc it(el) i( a very comple p#enomenon. InJdept# *nder(tandin o) t#e p#y(ic( o) t#e arc

i( o) little val*e to t#e 'elder8 ,*t (ome kno'lede o) it( eneral c#aracteri(tic( can ,e *(e)*l.

N,+:"% /0 +9% A"#

%n arc i( an electric c*rrent )lo'in ,et'een t'o electrode( t#ro*# an ioni!ed col*mn o) a(.

% neatively c#ared cat#ode and a po(itively c#ared anode create t#e inten(e #eat o) t#e 'eldinarc. Neative and po(itive ion( are ,o*nced o)) o) eac# ot#er in t#e pla(ma col*mn at an acceleratedrate.

In 'eldin8 t#e arc not only provide( t#e #eat needed to melt t#e electrode and t#e ,a(e metal8,*t *nder certain condition( m*(t al(o (*pply t#e mean( to tran(port t#e molten metal )rom t#e tip o)

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t#e electrode to t#e 'ork. Several mec#ani(m( )or metal tran()er ei(t. 'o 3o) many5 eample(incl*de:

S*r)ace en(ion ran()er J a drop o) molten metal to*c#e( t#e molten metal pool and i( dra'ninto it ,y (*r)ace ten(ion.

Spray %rc J t#e drop i( eMected )rom t#e molten metal at t#e electrode tip ,y an electric pinc#propellin it to t#e molten pool. 3reat )or over#ead 'eldinW5

I) an electrode i( con(*ma,le8 t#e tip melt( *nder t#e #eat o) t#e arc and molten droplet( aredetac#ed and tran(ported to t#e 'ork t#ro*# t#e arc col*mn. %ny arc 'eldin (y(tem in '#ic# t#eelectrode i( melted o)) to ,ecome part o) t#e 'eld i( de(cri,ed a( metalJarc. In car,on or t*n(ten3I5 'eldin t#ere are no molten droplet( to ,e )orced acro(( t#e ap and onto t#e 'ork. 2iller metali( melted into t#e Moint )rom a (eparate rod or 'ire.

ore o) t#e #eat developed ,y t#e arc i( tran()erred to t#e 'eld pool 'it# con(*ma,le

electrode(. #i( prod*ce( #i#er t#ermal e))iciencie( and narro'er #eatJa))ected !one(.

Since t#ere m*(t ,e an ioni!ed pat# to cond*ct electricity acro(( a ap8 t#e mere ('itc#in ono) t#e 'eldin c*rrent 'it# an electrically cold electrode po(ed over it 'ill not (tart t#e arc. #e arcm*(t ,e inited. #i( i( ca*(ed ,y eit#er (*pplyin an initial voltae #i# eno*# to ca*(e a di(c#areor ,y to*c#in t#e electrode to t#e 'ork and t#en 'it#dra'in it a( t#e contact area ,ecome( #eated.

%rc 'eldin may ,e done 'it# direct c*rrent 3C-5 'it# t#e electrode eit#er po(itive orneative or alternatin c*rrent 3%-5. #e c#oice o) c*rrent and polarity depend( on t#e proce((8 t#etype o) electrode8 t#e arc atmo(p#ere8 and t#e metal ,ein 'elded.

INERT GAS WELDING

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M%+,& I)%"+ G,- MIG W%&'()*: %n arc i( (tr*ck ,et'een a con(*ma,le electrode and t#e(#eet metal to ,e 'elded. #e con(*ma,le electrode i( in t#e )orm o) contin*o*( )iller metal. %n inerta( (*rro*nd( t#e arc and (#ield( it )rom t#e am,ient to prevent oidation.-ar,on (teel(8 lo' alloy (teel(8 (tainle(( (teel(8 mo(t al*min*m alloy(8 !inc ,a(ed copper alloy( can ,e'elded *(in t#i( proce((.

T:)*-+%) I)%"+ G,- TIG W%&'()*: %n arc i( tr*ck ,et'een a t*n(ten electrode 3nonJcon(*ma,le5 and t#e (#eet metal to ,e 'elded. %n inert a( (#ield( t#e arc )rom t#e am,ient to preventoidation. % )iller material i( optionalA

-ar,on (teel(8 lo' alloy (teel(8 (tainle(( (teel(8 mo(t al*min*m alloy(8 !inc ,a(ed copper alloy(can ,e 'elded *(in t#i( proce((. I i( B*ite (*ita,le )or 'eldin di((imilar material(8 ,*t *(*alca*tion( o) alvanic corro(ion (till apply.

#e I proce(( i( a (lo'er proce(( compared to t#e I proce((8 ,*t t#e B*ality o) 'eld i(co(metically ,etter. #ere i( no 'eld (patter8 and t#e B*ality o) 'eld( i( #i#er t#an I 'eldin.

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M,):0,#+:"()* C/)-('%",+(/)-

I 'eldin can ,e done )or t#ickne((e( ranin )rom 0.> mm to 6.+ mm 30.0D0 to 0.D>0 in5.I can ,e *(ed )or t#ickne((e( a( lo' a( 0.1D> mm 30.00> in5.

Geld (trent# can ,e *p to t#e (trent# o) t#e *nderlyin material. o improve overall (y(temro,*(tne(( it i( ,etter to increa(e material t#ickne(( rat#er t#an over (peci)yin t#e 'eld.

M,+%"(,& T9(#=)%-- ,)' W%&' S+"%)*+9

#e (*r)ace to ,e 'elded need( to ,e clean and derea(ed and any )orein de,ri( (#o*ld ,eremoved. In t#e ca(e o) #otJrolled (teel or al*min*m8 'ire ,r*(#in may need to ,e done to remove(cale( and oide(8 )or t#e #i#e(t B*ality 'eld(.

Geld di(tortion occ*r( '#enever a 'eld i( done. #i( can ,e minimi!ed ,y (pacin t#e 'eldtack( at lea(t >0 mm 3D in5 apart. Geldin di(tortion can al(o ,e minimi!ed ,y )it*rin 3and

clampin5 '#ile 'eldin a( 'ell a( #eat (inkin.

Hart( (#o*ld ,e de(ined 'it# )eat*re( t#at are (el)Jlocatin 'it# re(pect to matin part(. #i(remove( t#e need )or dedicated )it*re( and it( co(t(. 2it*re( al(o introd*ce additional tolerance( d*eto de)lection( impo(ed on t#e part( ,y t#e clampin pre((*re. 2it*re( can al(o (lo' do'n prod*ctiond*e to )act t#at part( #ave to ,e placed in t#e )it*re and clamp( 3i) any5 t#at need to ,e activated.

Geld( location( (#o*ld ,e located 'it# operator acce(( in mind. I) it i( not acce((i,le to a 'eldelectrode8 it i( not 'elda,le. #*(8 in de(in( t#at involve (ection( (*c# a( c#annel(8 ,oe( acce(( o)electrode( need( to ,e con(idered.

olerancin o) 'elded part( i( *(*ally enero*(. #i( allo'( t#e part( to ,e 'elded 'it#o*t toom*c# ela,orate )it*rin or (econdary proce((in (*c# a( rindin. I) ti#t tolerancin i( de(ired8 it i(

,e(t ac#ieved ,y (el)Jlocatin )eat*re( on t#e matin part(.

HEAT TREATMENT

/eat reatment i( t#e controlled #eatin and coolin o) metal( to alter t#eir p#y(ical andmec#anical propertie( 'it#o*t c#anin t#e prod*ct (#ape. /eat treatment i( (ometime( doneinadvertently d*e to man*)act*rin proce((e( t#at eit#er #eat or cool t#e metal (*c# a( 'eldin or

)ormin.

/eat reatment i( o)ten a((ociated 'it# increa(in t#e (trent# o) material8 ,*t it can al(o ,e*(ed to alter certain man*)act*ra,ility o,Mective( (*c# a( improve mac#inin8 improve )orma,ility8re(tore d*ctility a)ter a cold 'orkin operation. #*( it i( a very ena,lin man*)act*rin proce(( t#atcan not only #elp ot#er man*)act*rin proce((8 ,*t can al(o improve prod*ct per)ormance ,yincrea(in (trent# or ot#er de(ira,le c#aracteri(tic(.

Steel( are partic*larly (*ita,le )or #eat treatment8 (ince t#ey re(pond 'ell to #eat treatment andt#e commercial *(e o) (teel( eceed( t#at o) any ot#er material

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C//) H%,+ T"%,+%)+-

, S/0+%)()*: So)tenin i( done to red*ce (trent# or #ardne((, remove re(id*al (tre((e(8 improveto*#ne((8re(tore d*ctility, re)ine rain (i!eorc#ane t#e electromanetic propertie( o) t#e (teel.

&e(torin d*ctility or removin re(id*al (tre((e( i( a nece((ary operation '#en a lare amo*nto) cold 'orkin i( to ,e per)ormed8 (*c# a( in a coldJrollin operation or 'iredra'in. %nnealinX)*ll Hroce((8 (p#eroidi!in8 normali!in and temperin X a*(temperin8 martemperin are t#e

principal 'ay( ,y '#ic# (teel i( (o)tened.

S/0+%)()*

%nnealin i( t#e proce(( o) (lo'ly rai(in t#e temperat*re a,o*t >0 V- 390 V25 a,ove t#e%*(tenitic temperat*re line %+ or line %- in t#e ca(e o) /ypoe*tectoid (teel( 3(teel( 'it# Y 0.0 V- 390 V25 into t#e %*(teniteJ-ementite reion in t#e ca(e o) /ypere*tectoid (teel(3(teel( 'it# Z 0.< -ar,on5.

It i( #eld at t#i( temperat*re )or (*))icient time )or all t#e material to tran()orm into %*(teniteor %*(teniteJ-ementite a( t#e ca(e may ,e. It i( t#en (lo'ly cooled at t#e rate o) a,o*t D0 V-$#r 3+6V2$#r5 in a )*rnace to a,o*t >0 V- 390 V25 into t#e 2erriteJ-ementite rane. %t t#i( point8 it can ,ecooled in room temperat*re air 'it# nat*ral convection.

#e rain (tr*ct*re #a( coar(e Hearlite 'it# )errite or -ementite 3dependin on '#et#er #ypo or#yper e*tectoid5. #e (teel ,ecome( (o)t and d*ctile.

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N/",&(>()*i( t#e proce(( o) rai(in t#e temperat*re to over 60 V - 310= V25. It i( #eld at t#i(temperat*re to )*lly convert t#e (tr*ct*re into %*(tenite8 and t#en removed )orm t#e )*rnace andcooled at room temperat*re *nder nat*ral convection. #i( re(*lt( in a rain (tr*ct*re o) )ine Hearlite'it# ece(( o) 2errite or -ementite. #e re(*ltin material i( (o)tA t#e deree o) (o)tne(( depend( ont#e act*al am,ient condition( o) coolin. #i( proce(( i( con(idera,ly c#eaper t#an )*ll annealin

(ince t#ere i( not t#e added co(t o) controlled )*rnace coolin.

#e main di))erence ,et'een )*ll annealin and normali!in i( t#at )*lly annealed part( are*ni)orm in (o)tne(( 3and mac#ina,lilty5 t#ro*#o*t t#e entire partA (ince t#e entire part i( epo(ed tot#e controlled )*rnace coolin. In t#e ca(e o) t#e normali!ed part8 dependin on t#e part eometry8 t#ecoolin i( nonJ*ni)orm re(*ltin in nonJ*ni)orm material propertie( acro(( t#e part. #i( may not ,ede(ira,le i) )*rt#er mac#inin i( de(ired8 (ince it make( t#e mac#inin Mo, (ome'#at *npredicta,le. In(*c# a ca(e it i( ,etter to do )*ll annealin.

P"/#%-- A))%,&()* i( *(ed to treat 'orkJ#ardened part( made o*t o) lo'J-ar,on (teel( 3Y0.D>< -ar,on5. #i( allo'( t#e part( to ,e (o)t eno*# to *ndero )*rt#er cold 'orkin 'it#o*t

)ract*rin. Hroce(( annealin i( done ,y rai(in t#e temperat*re to M*(t ,elo' t#e 2erriteJ%*(tenitereion8 line %1on t#e diaram. #i( temperat*re i( a,o*t D V- 31+41 V25 (o #eatin it to a,o*t 00 V-31D9D V25 (#o*ld (*))ice. #i( i( #eld lon eno*# to allo' recry(talli!ation o) t#e )errite p#a(e8 andt#en cooled in (till air. Since t#e material (tay( in t#e (ame p#a(e t#ro*# o*t t#e proce((8 t#e onlyc#ane t#at occ*r( i( t#e (i!e8 (#ape and di(tri,*tion o) t#e rain (tr*ct*re. #i( proce(( i( c#eapert#an eit#er )*ll annealin or normali!in (ince t#e material i( not #eated to a very #i# temperat*re orcooled in a )*rnace.

S+"%-- R%&(%0 A))%,& i( *(ed to red*ce re(id*al (tre((e( in lare ca(tin(8 'elded part( andcoldJ)ormed part(. S*c# part( tend to #ave (tre((e( d*e to t#ermal cyclin or 'ork #ardenin. Hart( are#eated to temperat*re( o) *p to 600 J 6>0 V- 3111D J 1D0D V258 and #eld )or an etended time 3a,o*t 1#o*r or more5 and t#en (lo'ly cooled in (till air.

S49%"/('(>,+(/) i( an annealin proce(( *(ed )or #i# car,on (teel( 3-ar,on Z 0.60 to =00 V- 31+=DJ14D V25 and #old )or (everal #o*r( )ollo'ed,y (lo' coolin.

%ll t#e(e met#od( re(*lt in a (tr*ct*re in '#ic# all t#e -ementite i( in t#e )orm o) (malllo,*le( 3(p#eroid(5 di(per(ed t#ro*#o*t t#e )errite matri. #i( (tr*ct*re allo'( )or improved

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mac#inin in contin*o*( c*ttin operation( (*c# a( lat#e( and (cre' mac#ine(. Sp#eroidi!ation al(oimprove( re(i(tance to a,ra(ion.

T%4%"()* i( a proce(( done (*,(eB*ent to B*enc# #ardenin. F*enc#J#ardened part( areo)ten too ,rittle. #i( ,rittlene(( i( ca*(ed ,y a predominance o) arten(ite. #i( ,rittlene(( i(

removed ,y temperin. emperin re(*lt( in a de(ired com,ination o) #ardne((8 d*ctility8 to*#ne((8(trent#8 and (tr*ct*ral (ta,ility. emperin i( not to ,e con)*(ed 'it# temper( on rolled (tockJt#e(etemper( are an indication o) t#e deree o) cold 'ork per)ormed.

#e mec#ani(m o) temperin depend( on t#e (teel and t#e temperin temperat*re. #eprevalent arten(ite i( a (ome'#at *n(ta,le (tr*ct*re. G#en #eated8 t#e -ar,on atom( di))*(e )romarten(ite to )orm a car,ide precipitate and t#e conc*rrent )ormation o) 2errite and -ementite8 '#ic#i( t#e (ta,le )orm. ool (teel( )or eample8 lo(e a,o*t D to 4 point( o) #ardne(( on t#e &ock'ell -(cale. @ven t#o*# a little (trent# i( (acri)iced8 to*#ne(( 3a( mea(*red ,y impact (trent#5 i(increa(ed (*,(tantially. Sprin( and (*c# part( need to ,e m*c# to*#er X t#e(e are tempered to am*c# lo'er #ardne((.

emperin i( done immediately a)ter B*enc# #ardenin. G#en t#e (teel cool( to a,o*t 40 V-3104 V25 a)ter B*enc#in8 it i( ready to ,e tempered. #e part i( re#eated to a temperat*re o) 1>0 to400 V- 3+0D to >D V25. In t#i( reion a (o)ter and to*#er (tr*ct*re roo(tite i( )ormed. %lternatively8

t#e (teel can ,e #eated to a temperat*re o) 400 to 00 V- 3>D to 1D9D V25 t#at re(*lt( in a (o)ter(tr*ct*re kno'n a( Sor,ite. #i( #a( le(( (trent# t#an roo(tite ,*t more d*ctility and to*#ne((.

#e #eatin )or temperin i( ,e(t done ,y immer(in t#e part( in oil8 )or temperin *pto +>0 V-366D V25 and t#en #eatin t#e oil 'it# t#e part( to t#e appropriate temperat*re. /eatin in a ,at# al(oen(*re( t#at t#e entire part #a( t#e (ame temperat*re and 'ill *ndero t#e (ame temperin. 2ortemperat*re( a,ove +>0 V- 366D V25 it i( ,e(t to *(e a ,at# o) nitrate (alt(. #e (alt ,at#( can ,e #eated*pto 6D> V- 311> V25. &eardle(( o) t#e ,at#8 rad*al #eatin i( important to avoid crackin t#e (teel.%)ter reac#in t#e de(ired temperat*re8 t#e part( are #eld at t#at temperat*re )or a,o*t D #o*r(8 t#enremoved )rom t#e ,at# and cooled in (till air.

A:-+%4%"()* i( a B*enc#in tec#niB*e. #e part i( not B*enc#ed t#ro*# t#e arten(itetran()ormation. In(tead t#e material i( B*enc#ed a,ove t#e temperat*re '#en arten(ite )orm( S8aro*nd +1> V- 3600 V25. It i( #eld till at t#i( temperat*re till t#e entire part reac#e( t#i( temperat*re. %(t#e part i( #eld loner at t#i( temperat*re8 t#e %*(tenite tran()orm( into 7ainite. 7ainite i( to*#eno*# (o t#at )*rt#er temperin i( not nece((ary8 and t#e tendency to crack i( (everely red*ced.

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M,"+%4%"()*i( (imilar to %*(temperin ecept t#at t#e part i( (lo'ly cooled t#ro*# t#emarten(ite tran()ormation. #e (tr*ct*re i( marten(ite8 '#ic# need( to tempered M*(t a( m*c# a(marten(ite t#at i( )ormed t#ro*# rapid B*enc#in. #e ,ie(t advantae o) %*(temperin over rapidB*enc#in i( t#at t#ere i( le(( di(tortion and tendency to crack.

;H,"'%)()*: /ardenin o) (teel( i( done to increa(e t#e (trent# and 'ear propertie(. One o) t#e preJreB*i(ite( )or #ardenin i( (*))icient car,on and alloy content.I) t#ere i( (*))icient -ar,on content t#en

t#e (teel can ,e directly #ardened. Ot#er'i(e t#e (*r)ace o) t#e part #a( to ,e -ar,on enric#ed *(in(ome di))*(ion treatment #ardenin tec#niB*e(.

D(00:-(/) 9,"'%)()*

#e -ar,on content in t#e (teel determine( '#et#er it can ,e directly #ardened. I) t#e -ar,on

content i( lo' 3le(( t#an 0.D>< )or eample5 t#en an alternate mean( ei(t( to increa(e t#e -ar,oncontent o) t#e (*r)ace. #e part t#en can ,e #eatJtreated ,y eit#er B*enc#in in liB*id or coolin in (tillair dependin on t#e propertie( de(ired. Note t#at t#i( met#od 'ill only allo' #ardenin on t#e(*r)ace8 ,*t not in t#e core8 ,eca*(e t#e #i# car,on content i( only on t#e (*r)ace. #i( i( (ometime(very de(ira,le ,eca*(e it allo'( )or a #ard (*r)ace 'it# ood 'ear propertie( 3a( on ear teet#58 ,*t #a(a to*# core t#at 'ill per)orm 'ell *nder impact loadin.

C,";:"(>()*i( a proce(( o) addin -ar,on to t#e (*r)ace. #i( i( done ,y epo(in t#e part toa -ar,on ric# atmo(p#ere at an elevated temperat*re and allo'( di))*(ion to tran()er t#e -ar,on atom(into (teel. #i( di))*(ion 'ill 'ork only i) t#e (teel #a( lo' car,on content8 ,eca*(e di))*(ion 'ork( ont#e di))erential o) concentration principle. I)8 )or eample t#e (teel #ad #i# car,on content to ,ein'it#8 and i( #eated in a car,on )ree )*rnace8 (*c# a( air8 t#e car,on 'ill tend to di))*(e o*t o) t#e (teelre(*ltin in Cecar,*ri!ation.

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P,#= C,";:"(>()*: Hart( are packed in a #i# car,on medi*m (*c# a( car,on po'der or ca(tiron (#avin( and #eated in a )*rnace )or 1D to D #o*r( at 900 V- 316>D V25. %t t#i( temperat*re -Oa( i( prod*ced '#ic# i( a (tron red*cin aent. #e red*ction reaction occ*r( on t#e (*r)ace o) t#e(teel relea(in -ar,on8 '#ic# i( t#en di))*(ed into t#e (*r)ace d*e to t#e #i# temperat*re. G#eneno*# -ar,on i( a,(or,ed in(ide t#e part 3,a(ed on eperience and t#eoretical calc*lation( ,a(ed on

di))*(ion t#eory58 t#e part( are removed and can ,e (*,Mect to t#e normal #ardenin met#od(.

#e -ar,on on t#e (*r)ace i( 0.< to 1.D< dependin on proce(( condition(. #e #ardne((ac#ieved i( 60 J 6> &-. #e dept# o) t#e ca(e rane( )rom a,o*t 0.1 mm 30.004 in5 *pto 1.> mm 30.060in5. Some o) t#e pro,lem( 'it# pack car,*ri!in i( t#at t#e proce(( i( di))ic*lt to control a( )ar a(temperat*re *ni)ormity i( concerned8 and t#e #eatin i( ine))icient.

G,- C,";:"(>()*: a( -ar,*ri!in i( concept*ally t#e (ame a( pack car,*ri!in8 ecept t#at-ar,on onoide 3-O5 a( i( (*pplied to a #eated )*rnace and t#e red*ction reaction o) depo(ition o)car,on take( place on t#e (*r)ace o) t#e part. #i( proce(( overcome( mo(t o) t#e pro,lem( o) packcar,*ri!in. #e temperat*re di))*(ion i( a( ood a( it can ,e 'it# a )*rnace. #e only concern i( to

(a)ely contain t#e -O a(. % variation o) a( car,*ri!in i( '#en alco#ol i( dripped into t#e )*rnaceand it volatili!e( readily to provide t#e red*cin reaction )or t#e depo(ition o) t#e car,on.

L(@:(' C,";:"(>()*: #e (teel part( are immer(ed in a molten car,on ric# ,at#. In t#e pa(t8(*c# ,at#( #ave cyanide 3-N5 a( t#e main component. /o'ever8 (a)ety concern( #ave led to nonJtoic

,at#( t#at ac#ieve t#e (ame re(*lt.

N(+"('()* i( a proce(( o) di))*(in Nitroen into t#e (*r)ace o) (teel. #e Nitroen )orm(Nitride( 'it# element( (*c# a( %l*min*m8 -#romi*m8 oly,den*m8 and Qanadi*m. #e part( are#eatJtreated and tempered ,e)ore nitridin. #e part( are t#en cleaned and #eated in a )*rnace in anatmo(p#ere o) di((ociated %mmonia 3containin N and /5 )or 10 to 40 #o*r( at >00J6D> V- 39+D J11> V25. Nitroen di))*(e( into t#e (teel and )orm( nitride alloy(8 and oe( to a dept# o) *p to 0.6>mm 30.0D> in5. #e ca(e i( very #ard and di(tortion i( lo'. No )*rt#er #eat treatment i( reB*iredA in)act8 )*rt#er #eat treatment can crack t#e #ard ca(e. Since t#e ca(e i( t#in8 (*r)ace rindin i( notrecommended. #i( can re(trict t#e *(e o) nitridin to (*r)ace( t#at reB*ire a very (moot# )ini(#.

C,";/)(+"('()*proce(( i( mo(t (*ita,le )or lo' car,on and lo' car,on alloy (teel(. In t#i(proce((8 ,ot# -ar,on and Nitroen are di))*(ed into t#e (*r)ace. #e part( are #eated in an atmo(p#ereo) #ydrocar,on 3(*c# a( met#ane or propane5 mied 'it# %mmonia 3N/+5. #e proce(( i( a mi o)-ar,*ri!in and Nitridin.

-ar,*ri!in involve( #i# temperat*re( 3aro*nd 900 V-8 16>D V25 and Nitridin involve( m*c#lo'er temperat*re( 3aro*nd 600 V-8 111D V25. -ar,onitridin i( done at temperat*re( o) 60 J =0 V-31400 J 1>9= V258 '#ic# i( #i#er t#an t#e tran()ormation temperat*re( o) (teel t#at i( t#e reion o) t#e)aceJcentered %*(tenite.

It i( t#en B*enc#ed in a nat*ral a( 3Oyen )ree5 atmo(p#ere. #e(e B*enc#e( are le(( dra(tict#an 'ater or oilJt#*( le(( di(tortion. /o'ever t#i( proce(( i( not (*ita,le )or #i# preci(ion part( d*eto t#e di(tortion( t#at are in#erent. #e #ardne(( ac#ieved i( (imilar to car,*ri!in 360 J 6> &-5 ,*t nota( #i# a( Nitridin 30 &-5. #e ca(e dept# i( )rom 0.1 to 0.> mm 30.004 to 0.0+0 in5. #e ca(e i(ric# in Nitride( a( 'ell a( arten(ite. emperin i( nece((ary to red*ce t#e ,rittlene((.

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C//) S%&%#+(?% H,"'%)()* P"/#%--%-

F&,% H,"'%)()*: % #i# inten(ity oyJacetylene )lame i( applied to t#e (elective reion. #etemperat*re i( rai(ed #i# eno*# to ,e in t#e reion o) %*(tenite tran()ormation. #e Uri#tUtemperat*re i( determined ,y t#e operator ,a(ed on eperience ,y 'atc#in t#e color o) t#e (teel. #e

overall #eat tran()er i( limited ,y t#e torc# and t#*( t#e interior never reac#e( t#e #i# temperat*re.#e #eated reion i( B*enc#ed to ac#ieve t#e de(ired #ardne((. emperin can ,e done to eliminate

,rittlene((.

#e dept# o) #ardenin can ,e increa(ed ,y increa(in t#e #eatin time. %( m*c# a( 6.+ mm30.D> in5 o) dept# can ,e ac#ieved. In addition8 lare part(8 '#ic# 'ill not normally )it in a )*rnace8can ,e #eatJtreated.

I)':#+(/) H,"'%)()*: In Ind*ction #ardenin8 t#e (teel part i( placed in(ide a electrical coil'#ic# #a( alternatin c*rrent t#ro*# it. #i( eneri!e( t#e (teel part and #eat( it *p. Cependin on t#e)reB*ency and amperae8 t#e rate o) #eatin a( 'ell a( t#e dept# o) #eatin can ,e controlled. /ence8

t#i( i( 'ell (*ited )or (*r)ace #eat treatment. #e detail( o) #eat treatment are (imilar to )lame#ardenin.

L,-%" B%, H,"'%)()*: La(er ,eam #ardenin i( anot#er variation o) )lame #ardenin. %p#o(p#ate coatin i( applied over t#e (teel to )acilitate a,(orption o) t#e la(er enery. #e (electedarea( o) t#e part are epo(ed to la(er enery. #i( ca*(e( t#e (elected area( to #eat. 7y varyin t#e

po'er o) t#e la(er8 t#e dept# o) #eat a,(orption can ,e controlled. #e part( are t#en B*enc#ed andtempered. #i( proce(( i( very preci(e in applyin #eat (electively to t#e area( t#at need to ,e #eatJtreated. 2*rt#er8 t#i( proce(( can ,e r*n at #i# (peed(8 prod*ce( very little di(tortion.

E&%#+"/) B%, H,"'%)()*: @lectron 7eam /ardenin i( (imilar to la(er ,eam #ardenin. #e#eat (o*rce i( a ,eam o) #i#Jenery electron(. #e ,eam i( manip*lated *(in electromanetic coil(.#e proce(( can ,e #i#ly a*tomated8 ,*t need( to ,e per)ormed *nder vac**m condition( (ince t#eelectron ,eam( di((ipate ea(ily in air. %( in la(er ,eam #ardenin8 t#e (*r)ace can ,e #ardened very

preci(ely ,ot# in dept# and in location.

H,"')%--i( a )*nction o) t#e -ar,on content o) t#e (teel. /ardenin o) (teel reB*ire( a c#anein (tr*ct*re )rom t#e ,odyJcentered c*,ic (tr*ct*re )o*nd at room temperat*re to t#e )aceJcenteredc*,ic (tr*ct*re )o*nd in t#e %*(tenitic reion. #e (teel i( #eated to %*tenitic reion. G#en (*ddenlyB*enc#ed8 t#e arten(ite i( )ormed. #i( i( a very (tron and ,rittle (tr*ct*re. G#en (lo'ly B*enc#edit 'o*ld )orm %*(tenite and Hearlite '#ic# i( a partly #ard and partly (o)t (tr*ct*re. G#en t#e coolin

rate i( etremely (lo' t#en it 'o*ld ,e mo(tly Hearlite '#ic# i( etremely (o)t.

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/ardena,ility8 '#ic# i( a mea(*re o) t#e dept# o) )*ll #ardne(( ac#ieved8 i( related to t#e typeand amo*nt o) alloyin element(. Ci))erent alloy(8 '#ic# #ave t#e (ame amo*nt o) -ar,on content8'ill ac#ieve t#e (ame amo*nt o) maim*m #ardne((A #o'ever8 t#e dept# o) )*ll #ardne(( 'ill vary'it# t#e di))erent alloy(. #e rea(on to alloy (teel( i( not to increa(e t#eir (trent#8 ,*t increa(e t#eir#ardena,ility 8 t#e ea(e 'it# '#ic# )*ll #ardne(( can ,e ac#ieved t#ro*#o*t t#e material.

T(*ally '#en #ot (teel i( B*enc#ed8 mo(t o) t#e coolin #appen( at t#e (*r)ace8 a( doe( t#e#ardenin. #i( propaate( into t#e dept# o) t#e material. %lloyin #elp( in t#e #ardenin and ,ydeterminin t#e ri#t alloy one can ac#ieve t#e de(ired propertie( )or t#e partic*lar application.

S*c# alloyin al(o #elp( in red*cin t#e need )or a rapid B*enc# coolinA t#ere,y eliminatedi(tortion( and potential crackin. In addition8 t#ick (ection( can ,e #ardened )*lly.

:%)#9 M%'(,

:%)#9()*i( t#e act o) rapidly coolin t#e #ot (teel to #arden t#e (teel.

W,+%": F*enc#in can ,e done ,y pl*nin t#e #ot (teel in 'ater. #e 'ater adMacent to t#e#ot (teel vapori!e(8 and t#ere i( no direct contact o) t#e 'ater 'it# t#e (teel. #i( (lo'( do'n coolin*ntil t#e ,*,,le( ,reak and allo' 'ater contact 'it# t#e #ot (teel. %( t#e 'ater contact( and ,oil(8 areat amo*nt o) #eat i( removed )rom t#e (teel. Git# ood aitation8 ,*,,le( can ,e prevented )rom(tickin to t#e (teel8 and t#ere,y prevent (o)t (pot(.

Gater i( a ood rapid B*enc#in medi*m8 provided ood aitation i( done. /o'ever8 'ater i(corro(ive 'it# (teel8 and t#e rapid coolin can (ometime( ca*(e di(tortion or crackin.

S,&+ W,+%"Salt 'ater i( a more rapid B*enc# medi*m t#an plain 'ater ,eca*(e t#e ,*,,le(are ,roken ea(ily and allo' )or rapid coolin o) t#e part. /o'ever8 (alt 'ater i( even more corro(ivet#an plain 'ater8 and #ence m*(t ,e rin(ed o)) immediately.

O(&Oil i( *(ed '#en a (lo'er coolin rate i( de(ired. Since oil #a( a very #i# ,oilin point8t#e tran(ition )rom (tart o) arten(ite )ormation to t#e )ini(# i( (lo' and t#i( red*ce( t#e likeli#ood o)crackin. Oil B*enc#in re(*lt( in )*me(8 (pill(8 and (ometime( a )ire #a!ard.

P/&%" @:%)#9Holymer B*enc#e( t#at 'ill prod*ce a coolin rate in ,et'een 'ater and oil.#e coolin rate can ,e altered ,y varyin t#e component( in t#e mit*reJa( t#e(e are compo(ed o)'ater and (ome lycol polymer(. Holymer B*enc#e( are capa,le o) prod*cin repeata,le re(*lt( 'it#

le(( corro(ion t#an 'ater and le(( o) a )ire #a!ard t#an oil. 7*t8 t#e(e repeata,le re(*lt( are po((i,leonly 'it# con(tant monitorin o) t#e c#emi(try.

C"/*%)(# :%)#9-ryoenic( or deep )ree!in i( done to make (*re t#ere i( no retained%*(tenite d*rin B*enc#in. #e amo*nt o) arten(ite )ormed at B*enc#in i( a )*nction o) t#e lo'e(ttemperat*re enco*ntered. %t any iven temperat*re o) B*enc#in t#ere i( a certain amo*nt o)arten(ite and t#e ,alance i( *ntran()ormed %*(tenite. #i( *ntran()ormed %*(tenite i( very ,rittleand can ca*(e lo(( o) (trent# or #ardne((8 dimen(ional in(ta,ility8 or crackin.

F*enc#e( are *(*ally done to room temperat*re. o(t medi*m car,on (teel( and lo' alloy(teel( *ndero tran()ormation to 100< arten(ite at room temperat*re. /o'ever8 #i# car,on and

#i# alloy (teel( #ave retained %*(tenite at room temperat*re. o eliminate retained %*(tenite8 t#eB*enc# temperat*re #a( to ,e lo'ered. #i( i( t#e rea(on to *(e cryoenic B*enc#in.

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F/"*()* i( t#e proce(( ,y '#ic# metal i( #eated and i( (#aped ,y pla(tic de)ormation ,y(*ita,ly applyin compre((ive )orce. T(*ally t#e compre((ive )orce i( in t#e )orm o) #ammer ,lo'(*(in a po'er #ammer or a pre((.

2orin re)ine( t#e rain (tr*ct*re

and

improve( p#y(ical propertie( o) t#e metal. Git# properde(in8 t#e rain )lo' can ,e oriented in t#e direction o) principal (tre((e( enco*ntered in act*al *(e.rain )lo' i( t#e direction o) t#e pattern t#at t#e cry(tal( take d*rin pla(tic de)ormation. H#y(ical

propertie( 3(*c# a( (trent#8 d*ctility and to*#ne((5 are m*c# ,etter in a )orin t#an in t#e ,a(emetal8 '#ic# #a(8 cry(tal( randomly oriented.

2orin( are con(i(tent )rom piece to piece8 'it#o*t any o) t#e poro(ity8 void(8 incl*(ion( andot#er de)ect(. #*(8 )ini(#in operation( (*c# a( mac#inin do not epo(e void(8 ,eca*(e t#ere aren[tany. %l(o coatin operation( (*c# a( platin or paintin are (trai#t)or'ard d*e to a ood (*r)ace8'#ic# need( very little preparation.

2orin( yield part( t#at #ave #i# (trent# to 'ei#t ratioJt#*( are o)ten *(ed in t#e de(in o)aircra)t )rame mem,er(.

% 2ored metal can re(*lt in t#e )ollo'in

J Increa(e lent#8 decrea(e cro((J(ection8 called dra'in o*tt#e metal.J Cecrea(e lent#8 increa(e cro((J(ection8 called *p(ettin t#e metal.

J -#ane lent#8 c#ane cro((J(ection8 ,y (B*ee!in in clo(ed impre((ion die(. #i( re(*lt( in)avora,le rain )lo' )or (tron part(

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C//) F/"*()* P"/#%--%-

#e metal can ,e )ored #ot 3a,ove recry(talli!ation temperat*re(5 or cold.

O4%) D(% F/"*()*- H,)' F/"*()*-: Open die )orin( or #and )orin( are made 'it#

repeated ,lo'( in an open die8 '#ere t#e operator manip*late( t#e 'orkpiece in t#e die. #e )ini(#edprod*ct i( a ro*# approimation o) t#e die. #i( i( '#at a traditional ,lack(mit# doe(8 and i( an oldman*)act*rin proce((.

I4"%--(/) D(% F/"*()*- P"%#(-(/) F/"*()*-: Impre((ion die )orin( and preci(ion)orin( are )*rt#er re)inement( o) t#e ,locker )orin(. #e )ini(#ed part more clo(ely re(em,le( t#edie impre((ion.

% proper l*,ricant i( nece((ary )or makin ood )orin(. #e l*,ricant i( *(e)*l in preventin(tickin o) t#e 'orkpiece to t#e die8 and al(o act( a( a t#ermal in(*lator to #elp red*ce die 'ear.

P"%-- F/"*()*-: Hre(( )orin *(e a (lo' (B*ee!in action o) a pre((8 to tran()er a reatamo*nt o) compre((ive )orce to t#e 'orkpiece. Tnlike an openJdie )orin '#ere m*ltiple ,lo'(tran()er t#e compre((ive enery to t#e o*t(ide o) t#e prod*ct8 pre(( )orin tran()er( t#e )orce*ni)ormly to t#e ,*lk o) t#e material. #i( re(*lt( in *ni)orm material propertie( and i( nece((ary )orlare 'ei#t )orin(. Hart( made 'it# t#i( proce(( can ,e B*ite lare a( m*c# a( 1D> k 3D60 l,5 and+m 310 )eet5 lon.

U4-%+ F/"*()*-: Tp(et )orin increa(e( cro((J(ection ,y compre((in t#e lent#8 t#i( i( *(edin makin #ead( on ,olt( and )a(tener(8 valve( and ot#er (imilar part(.

R/&& F/"*()*-: In roll )orin8 a ,ar (tock8 ro*nd or )lat i( placed ,et'een die roller( '#ic#red*ce( t#e cro((J(ection and increa(e( t#e lent# to )orm part( (*c# a( ale(8 lea) (prin( etc. #i( i(e((entially a )orm o) dra' )orin.

S$,*()*: S'ain J a t*,e or rod i( )orced in(ide a die and t#e diameter i( red*ced a( t#ecylindrical o,Mect i( )ed. #e die #ammer( t#e diameter and ca*(e( t#e metal to )lo' in'ard ca*(int#e o*ter diameter o) t#e t*,e or t#e rod to take t#e (#ape o) t#e die.

N%+ S9,4% N%,"!N%+ S9,4% F/"*()*: In net (#ape or nearJnet (#ape )orin8 )orin re(*lt(in 'a(tae o) material in t#e )orm o) material )la(# and (*,(eB*ent mac#inin operation(. #i('a(tae can ,e a( #i# a( 0 < )or ear ,lank(8 and even 90 < in t#e ca(e o) aircra)t (tr*ct*ral part(.

NetJ(#ape and nearJnetJ(#ape proce((e( minimi!e t#e 'a(te ,y makin preci(ion die(8 prod*cin part('it# very little dra)t anle 3le(( t#an 1V5. #e(e type( o) proce((e( o)ten eliminate or red*cemac#inin.#e proce((e( are B*ite epen(ive in term( o) toolin and t#e capital ependit*re reB*ired.#*(8 t#e(e proce((e( can ,e only M*(ti)ied )or c*rrent proce((e( t#at are very 'a(te)*l '#ere t#ematerial (avin( 'ill pay )or t#e (ini)icant increa(e in toolin co(t(.

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TURNING

T:")()*i( t#e mac#inin operation t#at prod*ce( cylindrical part(. In it( ,a(ic )orm8 it can ,ede)ined a( t#e mac#inin o) an eternal (*r)ace:

J 'it# t#e 'orkpiece rotatin8J 'it# a (inleJpoint c*ttin tool8 andJ 'it# t#e c*ttin tool )eedin parallel to t#e ai( o) t#e 'orkpiece and at a di(tance t#at 'ill removet#e o*ter (*r)ace o) t#e 'ork.

aper t*rnin i( practically t#e (ame8 ecept t#at t#e c*tter pat# i( at an anle to t#e 'ork ai(.Similarly8 in conto*r t*rnin8 t#e di(tance o) t#e c*tter )rom t#e 'ork ai( i( varied to prod*ce t#ede(ired (#ape.

@ven t#o*# a (inleJpoint tool i( (peci)ied8 t#i( doe( not ecl*de m*ltipleJtool (et*p(8 '#ic# are

o)ten employed in t*rnin. In (*c# (et*p(8 eac# tool operate( independently a( a (inleJpoint c*tter.

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L,+9%

*rnin prod*ce( (olid( o) revol*tion '#ic# can ,e ti#tly toleranced ,eca*(e o) t#e

(peciali!ed nat*re o) t#e operation. *rnin i( per)ormed on a mac#ine called a lat#e in '#ic# t#e tooli( (tationary and t#e part i( rotated. #e )i*re ,elo' ill*(trate( an enine lat#e. Lat#e( are de(ined

(olely )or t*rnin operation(8 (o t#at preci(e control o) t#e c*ttin re(*lt( in ti#t tolerance(. #e 'orkpiece i( mo*nted on t#e c#*ck8 '#ic# rotate( relative to t#e (tationary tool.

C9:#=-

T9"%%!,$ C9:#=

% (piral ear me(#e( 'it# co teet# on t#e Ma'( to move all t#ree Ma'( in or o*t (im*ltaneo*(ly.

Hart( can ,e )it*red on o*ter or inner (*r)ace( (ince t#ere are rippin (*r)ace( on t#e inner and o*ter(*r)ace( o) t#e c#*ck Ma'(.

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F/:"!,$ C9:#=

I) t#e part need( to ,e o)) center or i( not a (olid o) revol*tion 3aially (ymmetric58 a )o*rJMa'c#*ck 'it# independentlyJact*ated Ma'( need( to ,e *(ed

A':-+,;&% #:++()* 0,#+/"- () +:")()*

#e t#ree primary )actor( in any ,a(ic t*rnin operation are (peed8 )eed8 and dept# o) c*t. Ot#er)actor( (*c# a( kind o) material and type o) tool #ave a lare in)l*ence8 o) co*r(e8 ,*t t#e(e t#ree aret#e one( t#e operator can c#ane ,y adM*(tin t#e control(8 ri#t at t#e mac#ine.

S4%%'al'ay( re)er( to t#e (pindle and t#e 'orkpiece. G#en it i( (tated in revol*tion( permin*te3rpm5 it tell( t#eir rotatin (peed. 7*t t#e important t#in )or a partic*lar t*rnin operation i(t#e (*r)ace (peed8 or t#e (peed at '#ic# t#e 'orkpiece material i( movin pa(t t#e c*ttin tool. It i((imply t#e prod*ct o) t#e rotatin (peed time( t#e circ*m)erence 3in )eet5 o) t#e 'orkpiece ,e)ore t#ec*t i( (tarted. It i( epre((ed in (*r)ace )eet per min*te 3()pm58 and it re)er( only to t#e 'orkpiece.@very di))erent diameter on a 'orkpiece 'ill #ave a di))erent c*ttin (peed8 even t#o*# t#e rotatin(peed remain( t#e (ame.

F%%'al'ay( re)er( to t#e c*ttin tool8 and it i( t#e rate at '#ic# t#e tool advance( alon it(c*ttin pat#. On mo(t po'erJ)ed lat#e(8 t#e )eed rate i( directly related to t#e (pindle (peed and i(epre((ed in inc#e( 3o) tool advance5 per revol*tion 3o) t#e (pindle58 or ipr.

D%4+9 /0 C:+i( practically (el) eplanatory. It i( t#e t#ickne(( o) t#e layer ,ein removed )romt#e 'orkpiece or t#e di(tance )rom t#e *nc*t (*r)ace o) t#e 'ork to t#e c*t (*r)ace8 epre((ed ininc#e(. It i( important to note8 t#o*#8 t#at t#e diameter o) t#e 'orkpiece i( red*ced ,y t'o time( t#edept# o) c*t ,eca*(e t#i( layer i( ,ein removed )rom ,ot# (ide( o) t#e 'orld

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LATHE RELATED OPERATIONS

#e lat#e8 o) co*r(e8 i( t#e ,a(ic t*rnin mac#ine. %part )rom t*rnin8 (everal ot#er operation(can al(o ,e per)ormed on a lat#e.

B/"()*7orin al'ay( involve( t#e enlarin o) an ei(tin #ole8 '#ic# may #ave ,een made ,ya drill or may ,e t#e re(*lt o) a core in a ca(tin. %n eB*ally important8 and conc*rrent8 p*rpo(e o),orin may ,e to make t#e #ole concentric 'it# t#e ai( o) rotation o) t#e 'orkpiece and t#*( correctany eccentricity t#at may #ave re(*lted )rom t#e drill[( #avin dri)ted o)) t#e center line. -oncentricityi( an important attri,*te o) ,ored #ole(. G#en ,orin i( done in a lat#e8 t#e 'ork *(*ally i( #eld in ac#*ck or on a )ace plate. /ole( may ,e ,ored (trai#t8 tapered8 or to irre*lar conto*r(. 7orin i(e((entially internal t*rnin '#ile )eedin t#e tool parallel to t#e rotation ai( o) t#e 'orkpiece.

F,#()*2acin i( t#e prod*cin o) a )lat (*r)ace a( t#e re(*lt o) a tool[( ,ein )ed acro(( t#e endo) t#e rotatin 'orkpiece. Tnle(( t#e 'ork i( #eld on a mandrel8 i) ,ot# end( o) t#e 'ork are to ,e)aced8 it m*(t ,e t*rned end )or end a)ter t#e )ir(t end i( completed and t#e )acin operation repeated.

#e c*ttin (peed (#o*ld ,e determined )rom t#e lare(t diameter o) t#e (*r)ace to ,e )aced. 2acinmay ,e done eit#er )rom t#e o*t(ide in'ard or )rom t#e center o*t'ard. In eit#er ca(e8 t#e point o) t#etool m*(t ,e (et eactly at t#e #ei#t o) t#e center o) rotation. ,eca*(e t#e c*ttin )orce tend( to p*(#t#e tool a'ay )rom t#e 'ork8 it i( *(*ally de(ira,le to clamp t#e carriae to t#e lat#e ,ed d*rin eac#)acin c*t to prevent it )rom movin (li#tly and t#*( prod*cin a (*r)ace t#at i( not )lat. In t#e )acino) ca(tin or ot#er material( t#at #ave a #ard (*r)ace8 t#e dept# o) t#e )ir(t c*t (#o*ld ,e (*))icient to

penetrate t#e #ard material to avoid ece((ive tool 'ear.

P,"+()*Hartin i( t#e operation ,y '#ic# one (ection o) a 'orkpiece i( (evered )rom t#eremainder ,y mean( o) a c*to)) tool. 7eca*(e c*ttin tool( are B*ite t#in and m*(t #ave con(idera,leover#an8 t#i( proce(( i( le(( acc*rate and more di))ic*lt. #e tool (#o*ld ,e (et eactly at t#e #ei#t

o) t#e ai( o) rotation8 ,e kept (#arp8 #ave proper clearance anle(8 and ,e )ed into t#e 'orkpiece at aproper and *ni)orm )eed rate.

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T9"%,'()* Lat#e provided t#e )ir(t met#od )or c*ttin t#read( ,y mac#ine(. %lt#o*# mo(tt#read( are no' prod*ced ,y ot#er met#od(8 lat#e( (till provide t#e mo(t ver(atile and )*ndamentally(imple met#od. -on(eB*ently8 t#ey o)ten are *(ed )or c*ttin t#read( on (pecial 'orkpiece( '#ere t#econ)i*ration or non(tandard (i!e doe( not permit t#em to ,e made ,y le(( co(tly met#od(. #ere aret'o ,a(ic reB*irement( )or t#read c*ttin. %n acc*rately (#aped and properly mo*nted tool i( needed

,eca*(e t#read c*ttin i( a )ormJc*ttin operation. #e re(*ltin t#read pro)ile i( determined ,y t#e(#ape o) t#e tool and it( po(ition relative to t#e 'orkpiece. #e (econd ,y reB*irement i( t#at t#e toolm*(t move lonit*dinally in a (peci)ic relation(#ip to t#e rotation o) t#e 'orkpiece8 ,eca*(e t#i(determine( t#e lead o) t#e t#read. #i( reB*irement i( met t#ro*# t#e *(e o) t#e lead (cre' and t#e(plit *nit8 '#ic# provide po(itive motion o) t#e carriae relative to t#e rotation o) t#e (pindle.

CUTTING TOOLS FOR LATHES

T//& G%/%+"2or c*ttin tool(8 eometry depend( mainly on t#e propertie( o) t#e toolmaterial and t#e 'ork material. 2or (inle point tool(8 t#e mo(t important anle( are t#e rake anle(and t#e end and (ide relie) anle(.

#e ,ack rake anle a))ect( t#e a,ility o) t#e tool to (#ear t#e 'ork material and )orm t#e c#ip. Itcan ,e po(itive or neative. Ho(itive rake anle( red*ce t#e c*ttin )orce( re(*ltin in (mallerde)lection( o) t#e 'orkpiece8 tool #older8 and mac#ine. I) t#e ,ack rake anle i( too lare8 t#e (trent#o) t#e tool i( red*ced a( 'ell a( it( capacity to cond*ct #eat. In mac#inin #ard 'ork material(8 t#e

,ack rake anle m*(t ,e (mall8 even neative )or car,ide and diamond tool(.#e #i#er t#e #ardne((8t#e (maller t#e ,ack rake anle. 2or #i#J(peed (teel(8 ,ack rake anle i( normally c#o(en in t#e

po(itive rane.

#ere are many type( o) c*ttin tool( )or di))erent operation( (*c# a(:

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o(t lat#e operation( are done 'it# relatively (imple8 (inleJpoint c*ttin tool(. On ri#tJ#andand le)tJ#and t*rnin and )acin tool(8 t#e c*ttin take( place on t#e (ide o) t#e toolA t#ere)ore t#e (iderake anle i( o) primary importance and deep c*t( can ,e made. On t#e ro*ndJno(e t*rnin tool(8c*to)) tool(8 )ini(#in tool(8 and (ome t#readin tool(8 c*ttin take( place on or near t#e end o) t#e

tool8 and t#e ,ack rake i( t#ere)ore o) importance. S*c# tool( are *(ed 'it# relatively li#t dept#( o)c*t. 7eca*(e tool material( are epen(ive8 it i( de(ira,le to *(e a( little a( po((i,le. It i( e((ential8 at t#e(ame8 t#at t#e c*ttin tool ,e (*pported in a (tron8 riid manner to minimi!e de)lection and po((i,levi,ration.

#e tool ,it (#o*ld ,e clamped in t#e tool #older 'it# minim*m over#an. Ot#er'i(e8 tool c#atterand a poor (*r)ace )ini(# may re(*lt. In t#e *(e o) car,ide8 ceramic8 or coated car,ide( )or ma((

prod*ction 'ork8 t#ro'a'ay in(ert( are *(edA t#e(e can ,e p*rc#a(ed in reat variety o) (#ape(8eometric( 3no(e radi*(8 tool anle8 and roove eometry58 and (i!e(.

TURNING MACHINES

#e t*rnin mac#ine( are8 o) co*r(e8 every kind o) lat#e(. Lat#e( *(ed in man*)act*rin can ,ecla((i)ied a( enine8 t*rret8 a*tomatic(8 and n*merical control etc.

#ey are #eavy d*ty mac#ine tool( and #ave po'er drive )or all tool movement(. #eycommonly rane in (i!e )rom 1D to D4 inc#e( ('in and )rom D4 to 4= inc#e( center di(tance8 ,*t('in( *p to >0 inc#e( and center di(tance( *p to 1D )eet are not *ncommon. any enine lat#e( areeB*ipped 'it# c#ip pan( and ,*iltJin coolant circ*latin (y(tem.

*rret Lat#e(. In a t*rret lat#e8 a lonit*dinally )eeda,le8 #eaon t*rret replace( t#e tail(tock.#e t*rret8 on '#ic# (i tool( can ,e mo*nted8 can ,e rotated a,o*t a vertical ai( to ,rin eac# toolinto operatin po(ition8 and t#e entire *nit can ,e moved lonit*dinally8 eit#er ann*ally or ,y po'er8 to

provide )eed )or t#e tool(. G#en t#e t*rret a((em,ly i( ,acked a'ay )rom t#e (pindle ,y mean( o) acap(tan '#eel8 t#e t*rret indee( a*tomatically at t#e end o) it( movement t#*( ,rinin eac# o) t#e(i tool( into operatin po(ition. #e (B*are t*rret on t#e cro(( (lide can ,e rotated man*ally a,o*t avertical ai( to ,rin eac# o) t#e )o*r tool( into operatin po(ition. On mo(t mac#ine(8 t#e t*rret can ,emoved tran(ver(ely8 eit#er man*ally or ,y po'er8 ,y mean( o) t#e cro(( (lide8 and lonit*dinallyt#ro*# po'er or man*al operation o) t#e carriae.

#ro*# t#e(e ,a(ic )eat*re( o) a t*rret lat#e8 a n*m,er o) tool( can ,e (et on t#e mac#ine and

t#en B*ickly ,e ,ro*#t (*cce((ively into 'orkin po(ition (o t#at a complete part can ,e mac#ined'it#o*t t#e nece((ity )or )*rt#er adM*(tin8 c#anin tool(8 or makin mea(*rement(.

SinleJSpindle %*tomatic Scre' ac#ine(. #ere are t'o common type( o) (inleJ(pindle (cre'mac#ine(8 One8 an %merican development and commonly called t#e t*rret type 37ro'n \ S#arp5. #eot#er i( o) S'i(( oriin and i( re)erred to a( t#e ('i(( type. #e 7ro'n \ S#arp (cre' mac#ine i(e((entially a (mall a*tomatic t*rret lat#e8 de(ined )or ,ar (tock8 'it# t#e main t*rret mo*nted on t#ecro(( (lide. %ll motion( o) t#e t*rret8 cro(( (lide8 (pindle8 c#*ck8 and (tockJ)eed mec#ani(m arecontrolled ,y cam(. #e t*rret cam i( e((entially a proram t#at de)ine( t#e movement o) t#e t*rretd*rin a cycle. #e(e mac#ine( *(*ally are eB*ipped 'it# an a*tomatic rod )eedin maa!ine t#at)eed( a ne' lent# o) ,ar (tock into t#e collect a( (oon a( one rod i( completely *(ed.

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MILLING

illin i( *(ed in t#e metal'ork ind*(try and de)ined a( t#e proce(( o) c*ttin8 (#apin8 and)ini(#in a piece o) metal. It i( one o) (everal metal'orkin proce((e( t#at incl*de t*rnin8 'eldin8and )rinin. illin i( *(ed '#en more comple metal (#ape( are de(ired. #e proce(( i( *(ed to

create a n*m,er o) metal part( and (tr*ct*re( on everyt#in )rom rin( and ,racelet( to ,ride( and)rei#t (#ip(. ypically8 millin involve( c*ttin a'ay piece( o) metal to create dovetail(8 t#read(8

,evel(8 (lot(8 and ride(. #e rooved ede( o) coin( are a (imple eample o) t#e millin proce((.

illin proce((e( are divided into t#ree cateorie(:

P%"(49%",& M(&&()*In perip#eral 3or (la,5 millin8 t#e milled (*r)ace i( enerated ,y teet#located on t#e perip#ery o) t#e c*tter ,ody. #e ai( o) c*tter rotation i( enerally in a plane parallel tot#e 'orkpiece (*r)ace to ,e mac#ined.

F,#% M(&&()*In )ace millin8 t#e c*tter i( mo*nted on a (pindle #avin an ai( o) rotationperpendic*lar to t#e 'orkpiece (*r)ace. #e milled (*r)ace re(*lt( )rom t#e action o) c*ttin ede(located on t#e perip#ery and )ace o) t#e c*tter.

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E)' M(&&()*#e c*tter in end millin enerally rotate( on an ai( vertical to t#e 'orkpiece. Itcan ,e tilted to mac#ine tapered (*r)ace(. -*ttin teet# are located on ,ot# t#e end )ace o) t#e c*tterand t#e perip#ery o) t#e c*tter ,ody.

#e term millin i( applied al(o to t#e proce((in o) ot#er material(8 e..8 (oap8 tetile(8 andmetal(A proce((in e(ta,li(#ment( are o)ten called mill(8 e..8 l*m,er mill or (a'mill8 cotton mill8 and(*ar mill.

illin proce(( i( applied in vario*( 'ay( accordin to t#e nece((ary condition:

U4 M(&&()*Tp millin i( al(o re)erred to a( conventional millin. #e direction o) t#e c*tterrotation oppo(e( t#e )eed motion. 2or eample8 i) t#e c*tter rotate( clock'i(e8 t#e 'orkpiece i( )ed tot#e ri#t in *p millin.

D/$) M(&&()*Co'n millin i( al(o re)erred to a( clim, millin. #e direction o) c*tter

rotation i( (ame a( t#e )eed motion. 2or eample8 i) t#e c*tter rotate( co*nterclock'i(e8 t#e 'orkpiecei( )ed to t#e ri#t in do'n millin.

#e c#ip )ormation in do'n millin i( oppo(ite to t#e c#ip )ormation in *p millin. #e c*ttertoot# i( almo(t parallel to t#e top (*r)ace o) t#e 'orkpiece. #e c*tter toot# ,ein( to mill t#e )*ll c#ipt#ickne((. #en t#e c#ip t#ickne(( rad*ally decrea(e(.

E@:(4%)+-

illin i( done *(in millin mac#ine(8 '#ic# con(i(t o) a c*tter t#at rotate( on an ai( (imilarto a drill ,it and an adM*(ta,le 'orkta,le *pon '#ic# t#e metal i( placed. %cce((ory part( incl*de avi(e or clampin kit t#at attac#e( t#e metal to t#e 'orkta,le8 a diital (cale8 and a point ma(ter. #ec*tter i( )ied into po(ition and can only move *p and do'n8 '#ile t#e 'orkta,le i( a,le to move *pand do'n a( 'ell a( (ide to (ide and )ront to ,ack. In mo(t ca(e( a (inle c*tter i( *(edA #o'ever8 it i(

po((i,le to (im*ltaneo*(ly *(e (everal c*tter( d*rin t#e millin proce((.

#e rotatin c*tter i( *(ed to c*t t#e metal. #ere are (everal type( o) c*tter( or mill( incl*dinend mill(8 )acin mill(8 and )orm mill( JJ eac# (ervin a di))erent p*rpo(e. (illin c*tter( can ,econ(tr*cted )rom one o) t#e )ollo'in material(8 car,ide8 microrain car,ide8 ceramic8 co,alt8 #i#J(peed (teel8 and diamond H-C. -oatin( )or millin c*tter( incl*de titani*m nitride8 titani*mcar,onitride8 titani*m al*min*m nitride8 al*min*m titani*m nitride8 al*min*m oide8 c#romi*m

nitride8 !irconi*m nitride8 and diamond.5 2or eample8 end mill( c*t (lot( and pocket(A )ace mill( c*t)lat (*r)ace(A )orm mill( are *(ed )or millin dovetail( and ,evel( in metal. #e t#ree mo(t important)actor( in t#e millin proce(( are rotation (peed8 t#e c*ttin dept# and t#e (endin (peed8 or t#e rate at'#ic# metal i( )ed to t#e c*tter.

#ere are t#ree di))erent type( o) millin mac#ine(: vertical8 #ori!ontal8 and a com,ination o)t#e t'o. Qertical and #ori!ontal millin mac#ine( are mo(t commonly *(ed. In a vertical millinmac#ine8 t#e c*tter i( mo*nted on a vertical ai(A on a #ori!ontal millin mac#ine8 it i( mo*nted on t#e#ori!ontal ai(.

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http://cutting-tools.globalspec.com/Industrial-Directory/milling_cuttershttp://cutting-tools.globalspec.com/Industrial-Directory/milling_cuttershttp://cutting-tools.globalspec.com/Industrial-Directory/milling_cutters

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M,+%"(,&-

aterial( ,e(t (*ited )or millin are t#e (o)ter metal( and pla(tic(. %l*min*m and ,ra(( are t'ocommonly milled metal(A e)lon and Celrin are commonly milled pla(tic(. /o'ever8 t#e a,ility to milla metal i( typically limited only ,y t#e #ardne(( o) t#e c*tter. Special c*tter( can ,e o,tained )or

millin #arder material( and re)ractorie(. %lternatively very (#arp c*tter( are availa,le )or pla(tic( andeven 'ood.

SetJ*p and )it*rin.

% typical millin Mo, reB*ire( more time to (et *p t#e )it*rin to #old t#e Mo, t#en to act*allycomplete t#e Mo,W #*(8 )it*rin i( a critical part o) t#e millin proce((. 2it*rin may involve)a,rication o) a n*m,er o) ot#er piece( ,e)ore t#e act*al part i( man*)act*red.

CNC ,)' NC

illin can ,e per)ormed *nder comp*ter control. S*c# mill( called -omp*ter N*merical-ontrol or N*merical -ontrol mill( are ,ecomin increa(in common in (mall mac#ine (#op(.

#ere are n*mero*( variation( on t#e(e mill(A t#e mo(t intere(tin 3at lea(t )or @@(W5 are -N-mill( t#at mac#ine (imple circ*it ,oard(.

A'?,)+,*%- /0 (&&()*

JQery ood )or oneJo)) o,Mect(JQirt*ally any material can ,e milled 'it# a proper c*tterJ-omple part( 'it# #i# detailJolerance( o) 0.001U to 0.00+U are po((i,leJGei#t( )rom a )e' ram( to *p to 100 l,(

D(-,'?,)+,*%-

J% more red*ced (et o) )eat*re( po((i,le. -ertain )eat*re( are not po((i,leJore material( 'a(te t#an ca(tin type proce((e(JF*ite (lo'

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DRILLING

Crillin i( ea(ily t#e mo(t common mac#inin proce((. One e(timate i( t#at >< o) all metalJc*ttin material removed come( )rom drillin operation(.

Crillin involve( t#e creation o) #ole( t#at are ri#t circ*lar cylinder(.

#e c#ip( m*(t eit t#ro*# t#e )l*te( to t#e o*t(ide o) t#e tool. #e c*ttin )ront i( em,edded'it#in t#e 'orkpiece8 makin coolin di))ic*lt. #e c*ttin area can ,e )looded8 coolant (pray mi(t can

,e applied8 or coolant can ,e delivered t#ro*# t#e drill ,it (#a)t.

D"(&&()* C9,",#+%"(-+(#-

#e c#aracteri(tic( o) drillin t#at (et it apart )rom ot#er po'ered metal c*ttin operation( are:

J#e c#ip( m*(t eit o*t o) t#e #ole created ,y t#e c*ttin.J-#ip eit can ca*(e pro,lem( '#en c#ip( are lare and$or contin*o*(.J#e drill can 'ander *pon entrance and )or deep #ole(.J2or deep #ole( in lare 'orkpiece(8 coolant may need to ,e delivered t#ro*# t#e drill (#a)t to t#ec*ttin )ront.JO) t#e po'ered metal c*ttin proce((e(8 drillin on a drill pre(( i( t#e mo(t likely to ,e per)ormed ,y(omeone '#o i( not a mac#ini(t.

D"(&& P"%-- W/"= A"%,

#e 'orkpiece i( #eld in place ,y a -Jclamp (ince c*ttin )orce( can ,e B*ite lare. It i(danero*( to #old a 'orkpiece ,y #and d*rin drillin (ince c*ttin )orce( can *npredicta,ly et B*itelare and 'renc# t#e part a'ay. Good i( o)ten *(ed *nderneat# t#e part (o t#at t#e drill ,it canover(#oot 'it#o*t damain t#e ta,le. #e ta,le al(o #a( #ole( )or drill over(#oot a( 'ell a( 'ei#tred*ction. % t#reeJMa' c#*ck i( *(ed (ince t#ree point( determine a circle in t'o dimen(ion(. 2o*rJMa'c#*ck( are rarely (een (ince o))(et o) t#e ,it i( not nece((ary.

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D"(&& P"%--

-ompared to ot#er po'ered metal c*ttin tool(8 a drill pre(( i( )airly (imple8 ,*t it #a( evolvedinto a ver(atile nece((ity )or every mac#ine (#op.

% typical man*al drill pre((:

#e mo(t adM*(ta,le part o) t#e drill pre(( i( t#e vertical movement o) t#e drill ,it8 (ince t#i( i(t#e motion t#at i( *(ed in prod*ction.

J#e cap(tan '#eel 3%5 move( t#e drill #ead *p and do'n.J#i( movement can ,e locked 3C5Jand t#ere are pointJtoJpoint (top( 375 )or maintainin a (peci)ic lent# o) travel.Jradation( marked on t#e (tationary part o) t#e drill pre(( 3-5 let t#e operator kno' '#ere #e i(

vertically.J7ot# t#e drillin #ead and ta,le can move vertically and rotate a,o*t t#e vertical *ide po(t 3,5.J#e ,a(e o) t#e drill pre(( incorporate( a 'ork (*r)ace (imilar to t#e ta,le( )or over(i!e 'orkpiece(.#e ,a(e can ,e ,olted do'n8 ,*t o)ten i( not (ince )orce( on a drill pre(( do not typically ca*(e it totip over.

#e drill i( po'ered ,y an electric motor 3I5.

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D"(&&%' P,"+ D%-(*)

#e )ollo'in are *ideline( )or drilled part de(in.

1J%dvantae( o) drilled #ole( incl*de acc*racy and (#arpne(( o) ede(. Since mac#inin i( epen(ive

compared to ot#er man*)act*rin proce((e(8 drillin to create a #ole (#o*ld ,e M*(ti)ied ,y lookin atalternative(. 7e)ore addin drilled #ole( to a de(in8 a(k yo*r(el) '#et#er t#e #ole i( needed and$or'#et#er it can ,e ca(t8 molded8 or pierced 'it# (*))icient acc*racy in(tead o) drilled.

DJSpeci)y (tandard drill ,it (i!e(. Tn*(*al #ole (i!e( ,rin *p t#e co(t o) man*)act*rin t#ro*#

p*rc#a(in and inventory co(t(.+J#ro*# #ole( are pre)erred over ,lind #ole(. #i( #a( to do 'it# t#e )act t#at a ,lind #ole doe( not

provide a( m*c# lee'ay )or c#ip eit and coolin. Operation( (*c# a( reamin and t#readin a)terdrillin are more ea(ily cond*cted on a t#ro*# #ole.

4JCo not (peci)y )latJ,ottomed #ole(. 'i(t drill( create coneJ,ottomed #ole( and )latJ,ottom #ole(ca*(e pro,lem( 'it# reamin8 etc.>JI) po((i,le8 do not (peci)y #ole( t#at are (maller t#an oneJei#t# inc#e( in diameter. Crill( )or(maller #ole( tend to ,reak and )or convenient ma(( prod*ction8 are not recommended.6J2or lare #ole(8 try to ca(t in a preliminary #ole t#at m*(t only ,e ,ored o*t to (peci)ication. #i((ave( material8 tran(portation co(t8 and drillin co(t.JG#en dimen(ionin #ole(8 it i( ,etter to *(e rectan*lar rat#er t#an an*lar 3or polar5 coordinate(.%n*lar coordinate( 'ill reB*ire t#e mac#ini(t to (et *p a dividin #ead or to reJdimen(ion t#e part8

,ot# o) '#ic# take time.=Jinimi!e t#e n*m,er o) drilled #ole (i!e( (o t#at tool c#ane( are minimi!ed.9Jinimi!e t#e n*m,er o) direction( on t#e part t#at #ole( m*(t ,e drilled )rom.10J#e entrance and eit (*r)ace( o) a drilled #ole (#o*ld ,e perpendic*lar to t#e #ole ai(. #erea(on( )or t#i( are a( )ollo'(:

a5 Tpon entrance o) t#e drill8 t#e drill tip 'ill 'ander i) t#e (*r)ace t#at t#e tip contact( i( notperpendic*lar to t#e drill ai(.

,5 @it ,*rr( 'ill ,e *neven aro*nd t#e circ*m)erence o) t#e eit #ole. #i( can make ,*rr removaldi))ic*lt.

7ad and ood eample( o) entrance and eit land(

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11JInter(ection( o) drilled #ole( 'it# ot#er cavitie( (#o*ld ,e avoided i) at all po((i,le. I) inter(ection'it# a cavity i( *navoida,le8 t#e drill ai( (#o*ld at lea(t ,e o*t(ide o) t#e cavity.

1DJ On dra'in(8 m*ltiple #ole( in a )lat (*r)ace (#o*ld ,e located )rom t#e (ame #ori!ontal andvertical dat*m(.1+J I) t#ere are protr*(ion( (*rro*ndin a drilled #ole8 it may ,e di))ic*lt to ,rin t#e drill pre(( #eadclo(e to t#e entrance (*r)ace8 re(*ltin in a drill ,it t#at i( prone to 'anderin8 c#atter8 and ot#er

in(ta,ilitie(. #i( pro,lem can ,e (olved ,y providin a )it*re 'it# a drill ,*(#in clo(e to t#e drill,it. /o'ever8 part de(in m*(t allo' )or t#e operation.

14JCrilled /ole Cept#: Ceep8 narro' #ole( 'it# lent# to diameter ratio( o) larer t#an t#ree (#o*ld,e avoided. Ceeper #ole( are po((i,le ,*t t#e drill 'ill tend to 'ander and po((i,ly ,reak. One 'ay toavoid a deep8 narro' #ole i( to *(e a (tepped entrance. 7lind #ole( (#o*ld ,e drilled to a dept# D>