M-A18 488 DRILLING METAL MATRIX COMPOSITES(U) ARMY LAO COMMAND /WATERTONN MA MAIERIAL TECHNOLOGY LAB W S RICCI ET ALJAN 88 MTL-TR-VI-i

UNCLASSIFIED F/G 11/4 U

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MICROCOPY RESOLUTION rEST CHART

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DRILLING METAL MATRIX COMPOSITES

AD-A'190 480

WILLIAM S. RICCI, STACY E. SWIDER, and THOMAS J. MOORES- MATERIALS EXPLOITATION DIVISION

January 1988

Approved for public release; distribution unlimited.

N,

S USARMY -

V. LABORATORY COMMAND4.MATERIALS TECHNOLOGY U.S. ARMY MATERIALS TECHNOLOGY LABORATORYPLABORATORY Watertown, Massachusetts 02172-0001

~~~~~. ~ ~ V l r%,. - S4 j iSr - -w ~ .~~

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DRILLING METAL MATRIX COMPOSITES Final Report

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A William S. Ricci, Stacy E. Swider, andThomas J. Moores

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Presented at the Eastern Manufacturing Technology Conference, November 1987,Springfield, MA

9 KEY WORDS (C,toInue ev a, e voe if necesery and ,dewIfv by block number.

DrillsComposites

DiamonI

20 AB'TPRAC T ,Conlnue in reverso -Ie if nec- e .ry end idfntifv by b ock nuitmber)

(SEE REVERSE SIDE)

I

DD I JAN,, 1473 EDITION OF NOV ';S ISBSOLFT UNCLASSIFIED

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Block No. 20

ABSTRACT

- Polycrystalline diamond (PCD) tipped twist and spade drills, diamondplated twist and core drills, and the abrasive waterjet hole cuttingprocess were evaluated for drilling aluminum metal matrix compositesreinforced with SiC fibers or particulates. The diamond tipped twistdrills outperformed all other drills. Core drills were found to beviable alternatives for the production of larger holes in high volumefraction composites. Plated twist drills were viable alternatives forlow volume fraction particulate-ieinforced composites. Spade drillsfailed due to low edge strength. Abrasive waterjet hole cutting wassuccessful for rough, large diameter hole cutting. Recommended drilling

parameters are listed for all of the above techniques.

The failure of diamond coated drills used on metal matrix compositeswas found to have been due to diamond glazing by the hard and abrasivereinforcement material, and loading by the soft metallic matrix. It was

determined that the machinability/clitting rate of metal matrix compositescan be predicted by using the rule of mixtures and machinability data

for the individual components of a composite.TZ-High volume fraction re-inforcement composites were found to necessitate techniques and toolingsimilar to those used for diamond grinding. In contrast, low volume

fraction reinforcement composites required tool geometries similar to thoseused for workpiece materials which plastically deform and readily form

chips.

Accession For

NTIS GRA&IDTIC TABUn, u-,oanr2 cd EJJustification

"Distributicn/A val biiity Codes

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~t ISpecial

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INTRODUCTION

Previous experience has shown that conventional cutting tool materidls andgeometries are not satisfactory for machining metal matrix composites (MIMC). 1 Ofprimary concerns are shortened tool life and damage to the workpiece. The primaryreasons for the short tool life are the hardness and abrasiveness of the reinforcingphase. Damage to the work material is also closely related to the reinforcing phase.For example, delamination near the tool exit side of a fiber-reinforced composite canresult when excessive cutting forces are required whenever dulled tools are used.Figure I shows a severe case of delamination and petalling caused by excessive drillwear and inadequate part fixturing. Figure 2 is a radiograph which shows the extentof lateral fiber damage around an improperly drilled hole.

Diamond tools are used almost exclusively in the traditional machining processesfor composites containing more than 25 volume percent ceramic reinforcement. For 25v/o SiC/Al, a 257 increase in total machining time was needed compared to the samethickness of standard 6061-T6 aluminum alloy. This increases to 300% for 40 v/oSiC /Al composites.2 Other investigators 3 have shown similar results and have

• ,estimated fourfold increases in total machining costs for metal matrix composites.

Nontraditional drilling/hole cutting methods such as rotary ultrasonic drilling,laser, and ram electrical discharge machining (EDM) have been attempted on varioustypes of metal matrix composites. The EDM process was found to provide close dimensionalcontrol4 while laser drilling achieved high material removal rates, even though subsequentmachining operations were required to produce acceptable surface finishes. 5 Theseprocesses, however, are expensive and are often limited by workpiece thickness.

Methods for drilling SiC fiber- and particulate-reinforced aluminum MMC arepresented in this paper. Diamond plated core drills, diamond plated twist drills,and polycrystalline diamond tipped twist and spade drills are evaluated, as well asthe abrasive waterjet hole cutting process. Results of drilling experiments, to

,4'. include mechanisms of tool wear and recommended drilling methods, are also presentedPand are believed to be applicable to many material systems composed of a hard ceramic

reinforcing phase in a ductile metallic matrix.

EXPERIMENTAL

Fiber- and particulate-reinforced MNC were used in this investigation. Thefiber-reinforced material, produced by AVCO Specialty Materials Division, consisted

1. DANIEL, W. K., MARIS, J. L., and VAN FICLEN, R. C. Aluminum Metal Matrix Concepts for Missile Airframes. Vought Missiles andAdvanced Programs Division of LTV Aerospace and Defense Co., Contract F33615-80-324, Final Report, Air Force Wright AeronauticalLaboratory, Wright-Patterson Air Force Base, OH, AFWAL TR 84-3065, September 1984.

2. SCHOUTENS, J. E. Discontinuous Silicon Carbide Reinforced Aluminum Metal Matrix Composites Data Review. MMCIAC No. 461,MMCIAC/Kaman Tempo, Santa Barbara, CA, December 1984.

3. VAN DEN BERGH, M. R. DWAQ 20® Status: Machinability. Hardware Examples. Proceedings, Sixth Annual Discontinuous ReinforcedAluminum Composites Working Group Meeting, Park City, UT, January 4-6, 1984. Published by MMCIAC/Kaman Tempo, Santa Barbara,CA, April 1984.

4. MILLER, M. F., and SCHAEFER, W. H. Development of Improved Metal. Matrix Fabrication Techniques. Convair Aerospace Divisionof General Dynamics Corporation, Contract F33615-70-C-1460, Final Report, Air Force Materials Laboratory, Wright-Patterson Air ForceBase, O1, AFML TR 71-181, July 1971 (AD-890605).

5. HAN LFY, F., and HARDAGE, J. T. Manufacturing Methods for Machining Processes for High Modulus Composite Materials, Volume 1,Composite Machining landbook - Boron. Convair Aerospace Division of General Dynamics Corporation, Contract F33615-72-C-1504,Final Report, Air Force Materials Laboratory, Wright-Patterson Air Force Base, OH, AFML TR 73-124, Vol. 1, May 1973 (AD-766332).

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- -' -. .% - r.1s:," :,- , '.x r- r 7-'', , ,'.r W' mfl ;, I7 : : r : i L: . . ' fl = - -V-T r ;

of 45 v/o unidirectional SCS-2 SiC fibers in a 6061-T4 aluminuim matrix. The particu-late-reinforced material, produced by DWA, contained 30 v/o SiC in a 7091-T6 aluminummatrix. The thicknesses of the fiber- and particulate-reinforced composites were0.375" and 0.500", respectively. Photomicrographs of each workpiece material areshown in Figure 3.

Electroplated diamond core drills, diamond plated twist drills, polycrystallinediamond (PCD) tipped twist and spade drills, and standard carbide twist drills were

used. All drills were 0.50" in diameter. Photographs of each drill type are shownin Figure 4. It should be noted that both 00 negative and 180 positive rake angleswere used on the PCD tipped twist drills.

The test apparatus for conventional drilling consisted of a drill press with

adjustable spindle speed. Cutting forces and torques about the spindle axis weremonitored with a dynamometer attached to the worktable. A dial indicator was used to

measure the depth of cut into the workpiece as a function of time for all experiments.Drilling parameters for representative test runs are shown in Table 1. All thrust

force values were kept constant within +/- 20 lbf except where noted.

Table 1. DRILLING PARAMETERS

Spindle ThrustCr1 Hole Drill Tool Speed Force

No. Type Material Condition (rmp) (lbf) Coolant

1. Core SiCf/Al Dressed 1115 187.5 YP,

2. Jressed 660

3. Dressed 325

. New

5. Dressed

6. Dressed -

7. D i amord Plated New

I.. l75

9.

12. Diamond Tipped 1- .

(leg.) Twist

i3. Diamond Tipped .7.

14. Diamond Tipped

Spade

15. Carbide SiCp/Al

16. Diamond Plated

'7. Iiamond Tipped

S7

IL. 1. / %

iA al .'i% -.

Abrasive waterjet hole cutting was performed on a Flow Systems PASER abrasivewaterjet cutting system using a model 9X intensifier pump. Cutting parameters areshown in Table

T t . ,6RA' :vE qATERJETritJ C!, T T ING PARjI iT AS

-if ice l irnttlr (in.

%oJzzle ')imk,ter in. p

Standoff Distance (in. I .

RESULTS

*The effect of spindle speed on core drill performance_ was dt.'termi ned (hoi,-sItA 3). Of the three spindle speeds evaluated, 1115, 660 , and 32') rpmn no s Ign I f iltdiff"erence in penetration rate was observed. However, the. drill ii,d at I 12 rpmn

fa i Led after penetrating approximately 0. 100" into the workpi. I aI Illy Wa a tIH ited to tool load ing caused by insu ffic ient f lushing o I hi p at Ii i I pill

Thlt e-f fec tiveness of dress ing worn core drill s was, .vI iati L i--', . -la 1 hw

.att tog rate data for hole 4 which was drilIled with ai new tool , and It, 1 wiI ,Itd r IllIed unde r the same cond it ions wi th the same toolI a ft trI r-d rn In Wl!wiIT i ' Idressing stick. Dressing did restore the init ial -kit ting ~~ta . y

dr IllI. Cutting rates for both the new and thi. dr-s--l drill- d- I in. 1 -

af~ter only 0.100"' depth of cut. However, the ratt. oI d,, lint, it) Itt I1: I I .r

for the dressed tool was greater than that of tht-e new tool.

Visual inspection of the drills used for iiil,- Ir~~ u it-fd tt..jt trapid degradation in penetration rate experit'lre.d was- I rr>il t .1 lti;an >1

oa: tihe core drill. Diamond grains were worn flaC .. nd tilt lrn. tw-il ,d',a-

(li amond gra ins and be tween the bond matLr ix and t heL titt I [-, Ix a. 1 tIii. I , WA;re~ducedl. To alleviate the glazing problem, the thrwst tar... oI tHi tool Into ftworkpiece was increased from 187.5 lbf to 375 lbf 1,ir hole t Inl anl alt'npt to mak,

the bond matrix act ''softer.'' Cutting rate data tkir hol, () ea- 6 1It ia liv abouitdouble that of hole 5, but decreased dramatically ait a pprix iri lv 0.20(1" dtpt h o1

Cutt, (see Figure 5).

The rate of change in cutting rate for hole- 6 at 0i.200"' de pth of cut was similar11to that of hole 5 at its maximum penetration dtepth, I indicat ing that the same final;tage mechanism of tool wear was operative. Ther. wais some initial advantage toI!incroasing thrust force, e.g ., the maximum depth of cut be-fore- the rapid decline inlstting rate was delayeud from 0.100'" to 0.200''. It was felt, however, that increasing

thrIit force alone was only a part ial solut ion to thet tool wear problem, since drill sd fr wrkjeces greater than 0.20)0" inthickness woul d have to be redressed

1-,)r, a iingle hol1e could be completed.

3

%

. ~ ~ -*

The of fect of nc r, . d thi' t 1,1r,- on the tool into the workpiece was similarlytested for the diamond pl,l, J dri 1 1 i .ur.- 6, holes 7 and 8), however, no overall

.mprocement wsJ s,5,'n

The efect of proper coo nt apipl ic.ition was determined to be critical for thediamond plated drill hFi,r , i.Vs 14 and 10). Drills used without coolant, awater misc ible fluid, failed within 20 s,-conds and exhibited cutting torques 50%lower than those observed when coolant was used.

Improved f lushig within the cut area was attempted for the core drills. Thiswas accomplished for hole 11 by manually applying a 375 lbf load on the tool into the

-*P workpiece for three to four seconds followed by retracti.n of the tool and flushingOf the cut area for approximately one second. Cutting rate data for hole 11, shown-n Fire , was initially the same as that of hole 6, drilled with constant tool

,'"- load. but did not decrease significantly for the depth of cut tested. Also, the

cutting torque for hole II was 26,, higher than that of hole 6. Intermittent flushingof the c ut with coolant can therefore be used to control tool loading and delay theonset ot the rapid tool wear experienced when machining }I~tC.

Both the positive and the negative rake diamond tipped twist drills penetratedthe SiCf/Al workpiece within 10 seconds. However, the diamond tipped spade drillchipped and failed within 5 seconds.

Depth of cut versus time to attain that depth of cut is plotted for drills 8,11, '.2, and 14, which are representative of the best conditions for each drill type"''sted opn the SiCf/AI, in Figure 7. It is clear that the diamond tipped twist drills(1.5 ipm/0.0046 ipr) outperformed the diamond tipped spade drill (failed), diamondplated twist drill (0.047 ipm/0.00015 ipr) and the diamond plated core drill (0.035ipm, 0.O00 ipr). Although the speeds for the diamond plated twist drills were quite

.imilar to those of the diamond core drills, the core drills could be dressed andr'-e, whereas the diamond plated drills had to be discarded (Figure 8).

. Additional holes were drilled with the negative rake diamond tipped twist drilli"tk tho SiCf/AI composite to determine the drills wear rate and durability. Figure 9is ai plt of the number of holes drilled versus the time to complete each hole.i(7ttin- rate data for the diamond tipped drill declined at a rate of 6.25% per inch

fed. The wear land on the PCD tipped twist drill after 30 holes is shown in

CiiLtin,; performance data for standard carbide twist (hole 15), diamond platedI0 t,.it (holo 16), diamond tipped twist (hole 17) and diamond core drills (hole 18) are

"h,,wn in Fi:,,ure 11 for the 30 v/o SiC particulate reinforced aluminum. Drillingparam,,rtrs for e ach tool are shown in Table 1. The carbide twist drill began to cut,ot wore out after approximately 20 seconds. The diamond tipped twist drill (2.5ipm! 0.007 6 ipr) once again outperformed the diamond plated twist drill (0.42

ipm/0.ipm 0.0013 ipr) and the diamond core drill (0.12 ipm/0.0004 ipr). In addition,S th,- (!i m lnd coat ing on the d iamond plated twist drill used in produc ing hole 16 remained" I t t c t FI r(, 12)

ir i w-n e a d 10 b t d""o

Dri1lin~' performance data for holes S and 16, both drilled with diamond plated-,it Ldril and the same parameters, show the increased machinabilitv rate of the 30V, SiCp/AM composite over that of the 45 v,'o SiCf/AI composite (Figure 13).

>4 5 4

St

% .%%

% %~

,.Jp

Three 0.75" OD core drills were also used to make holes 19 to 21 in SiC 6061-T6Al, and 45 v/o SiCf/AI workpieces under the constant thrust force conditions shown inTable 1. Drilling performance data for these tests are shown in Figure 14. Cuttingrates for the SIC were 0.025 ipm, SiCf/Al 0.088 ipm and 6061-T6 Al 0.132 ipm. Similartests could not be conducted for the other frill types because of their inability tocut the SiC monolithic plate.

A photograph of typical abrasive waterjet holes cut in the SiCf/Al material isshown in Figure 15. Hole quality and dimensional accuracy were found to decrease

*with increased nozzle wear and cutting speed.

DISCUSSION

Experimental results have shown that the rapid wear of diamond plated drills isprimarily due to the onset and degree of glazing. When glazed, diamond grains wearflat and new cutting facets are infrequently exposed. Compounding this problem is

loading by aluminum which reduces the clearance between the bond and the workpiece.

Loading results in a "harder" acting bond since higher mechanical pressures ofdrilling are required to break the bond which holds the dull grains to the cutting

tool.

* Figure 16 is a typical dynamometer recording showing cutting torque versus timefor a core drilled hole in SiCf/Al composites. Figure 17 is a plot of cutting torqueversus depth of cut for this hole. The torque values shown in this figure represent

the torque required to machine through individual plies of SiC fibers which are theminimum values of the cyclic dynamometer torque recording of Figure 16. As shown inFigure 17, these torque values decline with depth of cut, indicating glazing as an

initial mechanism of tool wear. A nominally linear rate of decline in torque valuesoccurs to approximately 0.150" depth of cut and is followed by a more dramaticdecline. This change in slope indicated an additional mechanism of tool wear, loading

by the aluminum, which increases the degree of glazing beyond that which can beattributed to the machining of SiC plies alone.

In summary, the rapid wear rates for diamond plated drills used to machine 111C

are due to a combination of the hard and abrasive reinforcement which results indiamond glazing and the soft metallic matrix which loads the tool and eventually

accelerates the rate of tool glazing by preventing dulled cutting facets from beingdischarged from the tool bond. Low speeds, high feeds, frequent dressing, and proper

* coolant application are therefore recommended for the drilling of both the fiber- and

particulate reinforced composites.

Cutting rate data derived from Figure 14, which shows core drilling results onSiC, 6061-T6 Al, and SiCf/Al, indicate that the cutting rate of SiCf/Al can be pre-dicted by the rule of mixtures using machinability/cutting rate data for the twoindividual components of the composite, SiC and Al. One can assume that this notonly applies to SiCf/Al but to all aluminum matrix composites regardless of matrixand reinforcement composition. The form and distribution of the reinforcement may

-lter this relation in a secondary manner.

" Sine the mechanism of material removal for the reinforcement phase is vast lv"ifi-erent than that of the matrix material, e.g., brittle fracture versus shear,too)ls should be selected based on volume fraction reinforcement. High voimo

5

%

% %~. % %

' raction reinforcements require techniques and tooling similar to diamond grindingwh ile0 low VOIlume fraction reinforcement composites require tooling similar to thatused for materials which plastically deform and readily form chips.

Figure 13 shows that for the 45 v/o SiCf/Al the performance of the diamondplated twist drills and the diamond core drills are quite similar. Since significantwear of the plated twist drill prevented its reuse, core drills are considered to besiuperior to plated twist drills for high volume fraction reinforcement composites.Figure L3. however, also shows that for the 30 v/o SiC /Al, diamond plated twistdrills significantly outperform diamond core drills. The reduced volumo fraction ofSiC, the random dispersion of particulate, and the small 1/d ratio of the reinforcementire all believed to contribute to the enhanced performance of the diamond plated"wist drill on low volume fraction particulate-reinforced materials.

Since the diamond grit size on the plated twist drills is significantly largert han that of the core drills, the plated twist drills can tolerate larger volumefractions of matrix material without loading. However, larger grit sizes also cor-respond to weaker bond strengths which are a disadvantage when penetration throughnt merous plies of continuous fiber reinforcement is required.

A s hole size increases, the force required to remove a unit volume of chipsincreases at a faster rate for the plated twist drills than the core drills. Inaddition, since the diamond coated surface area of twist drills increases fasterV 7

with drill diameter than that of core drills, the cost difference between core and

twist drills decreases with drill size. For example, a 0.125" core drill costs 4rw. t m s much as a diamond plated twist drill of the same size. A 0.750 diameterc.r, drill costs l.5 times more than a twist drill of equivalent size. Therefore, asnol-, eize increases, core drilling and possibily abrasive waterjet cutting become

ztr,, viable 'Aternatives for low volume fraction reinforcement composites.

A similar cost/diameter ralationship exists between the core and diamond tippeddrills. For example, 0.125" diameter diamond tipped twist drills cost 2.5 times thato of tht same diameter core drill, whereas 0. 750" diameter diamond tipped drills may

" cost times as much. Although the cost of diamond tipped drills is high, cuttingspeeds are also high. There may be no other tool capable of producing holes inheavw sections of high volume fraction fiber-reinforced composites. These drillsmay, however, be proned to chipping if misused, as evidenced by the spade drillresults, but may be resharpened if removed from service before wear lands becomes-excessively large. However, the cost of regrinding is high. Negative rakediamond tipped drills are recommended over positive rake drills for additional edge

* •strength, especially with high volume fraction fiber-reinforced composites.

Abrasive waterjet hole cutting is a viable rough hole making process for alltpe oI composites. While tooling costs are low, initial capital investment_o)sts are-, however, high.

S$..

CO CLIJS IONS

Drill ing speeds/penet rat ion rates for 30 v/o Si C/A1 and 45 v/o SiCf/Al com-. L,,it,, wo re 2.5 ipm and 1.5 ipm respect ive lv , Ior the 0 .30' diameter polvcrvstal lineIi 171end tipped, negative rake, twist dri 1 Is. Th , dr ii Ing performance o f the(!I m nd plaited twist drills. diLr!Idoud cor- dril Is, a nd dJI .nd tipped spad, drills is

+, %

0..

Ok"

_ *. P . . -. . " *., . , , - . " " , * . " ' , - ' ..'j% * , .* , e ''* % , ' .# ' . -, ' , " " , - - , " , " . " , - -•+ . . " + , " - . " . " -" ." .-." , -. - . - • -, .-- .,,. ' , " ." .+ ' .." , " .+ ' ' -,i ' , + 7 + , + ' ', .7 , " , ; , ; -, ' " , ." e <' " , _" ' " , .' 2 '> - -" -" " .> ." , " , " , " ,' . . ., , -" " ." , " , " , ' ., . , " .. -. ' ., ' , .-.

inictior to that of the diamond tipped twist drills, especially for small holes.

Phe initial 'ost oC the tipped twist drills, however, is extremely high.

Dia-ii:ond core drills are a viable alternative for larger dian.ter holes in highvolume fraction reinforcement composites. Frequent dressing, low speeds, and high

ieeds are recommended for these drills. However, intermittent flushing of the cut

area e.c., interrupted feed rates) is required for high volume fraction rein-t or c men t compos ites.

I Diamond plated twist drills are a viable alternative for hole drilling low,I,:m. raction particiate reinforced materials. However, they cannot be success-L!v applied to hich volIme fraction fiber-reinforced composites. Unlike the other

d Ii tc, sted, nlated twi.st drills may not be resharpened. However, their cost is,)In i 10 that of a diamond tipped drill.

l Di:,,ond ctip:Ped s pad." drills are tinsuitable for fiber-reinforced composites dueSir i ; -st ren;' th.

rI wterjet hole cutting is viable alternative for rough, large diameter" ,, b,th particulate and fiber high volume fraction reinforcement

* f'II iilure, mecha:nism of any diamond coated drill used to machine metal matrixS.p, t. - primarily clated to the onset and degree of glazing. When glazed,ii amd r ins war -at and new cutting facets are infrequently exposed. Compound-

tn r pr b .m is loading which reduces the clearance between diamond grains and- ,.. : 1h, bond and the workpiece.

chci ma-hinability/cutting rate of any metal matrix composite can be predictedbvth )f mixturts using machinability/cutting rate data for the individual

mp nt< :- a composite.

-, 7

%0%

. z'% . %... % -. ° % - - . • . - .% % % " . .. . . . % % ".° ° - - ° . % % "

Figure 1. Delamination of a fiber-reinforced compositewhich resulted from excessive cutting forces. Dull tool

* at inset. Mag. 8X

6.,

6-,

% %

a * * 0(0

Fiber Reinforced, Mag. 50X

,h ''II,.

Talk An. V-

Lt, ,

L ,-.Ah A.

"_" Particulate Reinforced, Mag. 500X

•Figure 3. Photomicrographs of SiC metal matrix composites.

b.~ ~

0

~rnr~t

* 1 r.

* ~1 I

S

K * *)..,. I

0~

0

. K* .'~

1200

1100

Hole 4 = 187.5 lbf - New Tool000 j Hole 5 = 187.5 Ibf - Dressed Tool

Hole 6 = 375 Ibf - Dressed Tool

900 Hole 11 375 lbf Intermittent -Dressed

700 /eoo ///

600 / /

400

,;:::. -- / <

. o 00

55 100 -- e '

0 r

0 02 0 06 0.10 0.14 0.18 0.22 0.26 0.30 0.34

O lieplh if ( ul li i

Figure 5. Plot of depth of cut versus time to attain a given depth of cut forfour core drilling conditions.

J.2W1) 7- -

.+

+ 0

.NI

290+ 0

'.'+ [)

+ 3

'1') + 0 x )<x )X

+ 1

00

".-1,1)20 -

•x x x

. ),:)80 +

* + t Hole 7 187.5 Ibf woCoolant

:,.J0 fz -. r- I - T T T

l°-

! Hole 8 375 Ibf v'Coolant

"- ).,j,1 4x Hole 9 187.5 Ibf wil0 Coolant

+ 0A Hole 10 375 bf wMo Coola~t

j +) "fT T T r T - "T--T--- "q- -r---

0 40 80 120 160 200 240 280 320Time (sec)

Fiqute 6. The effect of thrust force and coolant on the performance of

* the diamond plated twist drills.

jdrills.

I010k .

0.500

0 H0le 8 Plated ',,ist Drill0 Hole 11 Core Drill

0.400 121 Hole 12 Tipped T.ist Drill

x Hole 14 Speed Drill

0,300

x OD 0 0

• -. 0. 200 o

[ 0 00

0 0J.0.100 00

0 I I I I I I

0 40 80 120 160 200 240 280 320STime (sec,

Figure 7. Plot of depth of cut versus time to attain a depth of cut into0 _the SiCf/AI with the diamond tipped twist and spade drills and the

diamond plated core and twist drills.

-.

-p .Figure 8. Diamond plated twist drill after one hole

into the SiCf/A. workpiece. Mag. 5X

12

.

*'*i~\ % V

, i

17216 0 00

015 0

14 0 00 00

j3H 0 000 00,'-- '13- 0 n o

12I- 00 00

11 o o0 0 ° o

. 10 C)

0

91 0

5432

%%0 4 8 12 16 20 24 2'8

• Number of Holes

Figure 9. Plot of the time to complete a hole versus number of holesdrilled for the PCID tipped twist drill.

.e

.,,J-.V.

",Figure 10. Wear land on the PCID tipped twist cirill

after 30 holes into SiCf/Al workpiece. Mag. 5X

13

04

""" ".

Wt ld I

-. p -, -JWW. W- IF -i.. TV

.V "

J 15

3, 450 - -. + Hole 15 Carbide Tv.i,,

4. .400 + Hole 11 Diamond Tipped b',ist

0 0

O 0 e btl i Diamond Plated l,',st

*O J5 A z 'ole is L c,,re Driil0.5] 30C~ .C'

0.0 - 0>

03.250-

0 0 000 - so

"-" 0. 150 -

'00 O.C0

040

0. 050- A A

0 . . -- 0 - - I T CD CD . .

S0 20 40 oO d

ime sec.

Figure 11. Plot of depth of cut versus milling time for the Si~p/AI*e workpiece with core drills and diamond tipped, diamond plated,

and carbide twist drills.

:',

,'

.J

Ssix holes into the SiC/Al workpiece. Mag. 5X

14

V. :0 pP !...% "~ . .. . . . .

"rh %, r .7r't- ' . -. • : - : . , Jr. o - v: x r'r: r rrr_ ; zw : r t .- r- r - .,?, - -

S.3209.300 .

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J. 2 3

0 '0 + 0 0 HGI P ate +. t ~

99~~~~~9~ + oe1 oe ie

-. 140 + o

- 9 9O A Hol 18Cr+ atclt0 + -

1 40 0 1'0 1

Figure1. HDt oe dil ated d.i.ost, F plateI 00 O + + Hole 11 Core, Fiber00 -O o [ + 0 Hole IO b Plated Tvist. Parti(.ulatt:

A'C' + n Hole 18 Core, Particulate

020 1%'. . ' 0 J -- 7-- - - T- - - - - T - - - T - I l I T

00 80 12 160 2.3 250 280 320Time (Sec)

" '.Figure 13. Depth of cut versus time for core drills and diamond plated

=,.twist drills used on both the SiCf/AI and SiC p/Al workpieces.

0.400 0 0 0

0

0

0o 2 0 ++

0 +

:1:0. 4 -0 0 i 0

~0.200 0 +

",~0 + ifA

1.50 0-0 +

0.100 0 + 0 000

0,050 EP0

-0 - T r T0 4) 80 120 160 9)

Time ' sec)

* Figure 14. Core drill performance data on SiC, 6061 -T6 Al and 45 v/oSiCf/AI workpieces.

15

S%

'' " - -' a o +~ + w~

% , Tie 'eV

C'I47Figure 15. The 0.25" and 0.50" diameter holes cut by the abrasive

waterjet process into the SiCf/AI workpiece.

TorquLC: 0.8 ft-lb div

Figure 16. Dynamometer recording showing torque data. Chart speed 1 mm/sec.

3.2-

3.1

3

2.9

2.8

2.7

2.6

2.5

2.4

4 2.3

* 2.2 j

2.1 ~*0 0.04 0.08 0.12 0.16 0.2 0.24

I Depth of( iut (in

Figure 17. Torque required to machine individual plies of SiC fibers versus depth of cut.

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1 ATTN: Mr. Robert J. Fioyrentino, Program Manager

tI fcense Advanced Research Projects, Agency. Defense Sciences Office/MSD,100 ilson Boulevard, Arlington, VA 2 "209

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