j o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338

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Some studies on drilling of hybrid metal matrix compositesbased on Taguchi techniques

S. Basavarajappaa,∗, G. Chandramohanb, J. Paulo Davimc

a Department of Mechanical Engineering, University BDT College of Engineering, Davanagere 577004, Indiab Department of Mechanical Engineering, PSG College of Technology, Coimbatore 641004, Indiac Department of Mechanical Engineering, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal

a r t i c l e i n f o

Article history:

Received 15 September 2006

Received in revised form 9 May 2007

Accepted 29 May 2007

a b s t r a c t

Drilling is a metal removal process and is important for the final fabrication stage prior to

application. This paper discusses the influence of cutting parameters on drilling characteris-

tics of hybrid metal matrix composites (MMCs)—Al2219/15SiCp and Al2219/15SiCp–3Gr. The

composites are fabricated using stir casting method. The Taguchi design of experiments and

analysis of variance (ANOVA) are employed to analyze the drilling characteristics of these

composites. The experiments were conducted to study the effect of spindle speed and feed

Keywords:

Drilling

Hybrid MMCs

Machinability

rate on feed force, surface finish and burr height using solid carbide multifacet drills of

5 mm diameter. The results reveal that the dependent variables are greatly influenced by

the feed rate rather than the speed for both the composites. The ceramic–graphite reinforced

composite has better machinibility than those reinforced with SiCp composites.

cutting properties.

ANOVA

1. Introduction

Considerable research in the field of material science hasbeen directed towards the development of new light-weight,high performance engineering materials like composites. Theapplications of these composite materials are among themost important developments in materials engineering inrecent years, metal matrix composites are one among them.Metal matrix composites have became the necessary materi-als in various engineering applications like aerospace, marine,automobile and turbine-compressor engineering applications,because of their light-weight, high strength, stiffness andresistance to high temperature (Ibrahim et al., 1991; Sinclairand Gregson, 1997; Goni et al., 2000). The applications ofMMCs are limited by their poor machinability, which is a result

of their highly abrasive nature. This causes excessive toolwear in cutting of ceramic reinforced aluminium matrix com-posites with tungsten carbide tools and even with diamond

∗ Corresponding author. Tel.: +91 8192 224557; fax: +91 8192 224557.E-mail address: basavarajappas@yahoo.com (S. Basavarajappa).

0924-0136/$ – see front matter © 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.jmatprotec.2007.05.043

© 2007 Elsevier B.V. All rights reserved.

tools (Manna and Bhattacharya, 2003). Although attemptshave been made to eliminate machining operations by usingfabrication techniques like near net shape forming and mod-ified casting, they are limited and therefore machining is stillan integral part of the component manufacture. However inview of the growing engineering applications of these com-posites, a need for detailed and systematic study of theirmachining characteristics and machinability was envisaged.By controlling the various parameters which influences themachinability, intended surface finish, reduced tool wear andcutting forces could be obtained. From the available literatureon machining MMCs, it is obvious that the morphology, dis-tribution and volume fraction of the reinforcement phase aswell the matrix properties, are all factors that affect the overall

The presence of hard ceramic particles in the compositesmakes them extremely difficult to machine as they lead torapid tool wear (Ciftci et al., 2004; Monaghan and O’Reilly,

t e c

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j o u r n a l o f m a t e r i a l s p r o c e s s i n g

992). The hard SiC particles in Al/SiC-MMCs, which intermit-ently come in contact with the tool surface and acts as smallutting edges like those of a grinding wheel on the cuttingool edge. These particles acts as abrasive between cuttingool and work piece and resulting in formation of high toolear, poor surface finish, high drilling forces and burr for-ation (Monaghan and O’Reilly, 1992; Mubaraki et al., 1995;

amulu et al., 2002). Paulo Davim and Conceicao AntonioDavim and Antonio, 2001) have conducted drilling tests withhe intention of developing optimal drilling conditions usingenetic algorithm approach. They noticed a predominantlybrasive wear mechanism attributed to the hard particles inhe matrix. The surface finish was found to be affected by theeed rate and not by the cutting speed. Ramulu et al. (Ramulut al., 2002) reported that the alumina particulates causedxtremely rapid flank wear in drilling tools, when machiningl2O3 particulate reinforced aluminium-based MMC. Among

he three tool materials studied, polycrystalline diamondPCD) drills possessed the highest resistance to tool wear andhey are recommended for finish machining operations under

ost cutting conditions. The carbide tipped drill also showedcceptable drilling forces and hole quality. In this case, carbideipped drills can be used under compromised conditions. HSSrills are unsuitable for drilling of ceramic reinforced MMCsecause of very high tool wear, poor hole quality and higherrilling forces induced. Mubaraki et al. (Mubaraki et al., 1995)xamined the wear behaviour of HSS, WC and PCD tools inrilling of Al2O3 reinforced Al alloy particulate metal matrixomposites, and seeks to establish a correlation between theank wear and measurement of forces.

Sharma et al. (Sharma et al., 1996) reported that the toolife of HSS drill gets increased while machining graphite rein-orced aluminium matrix composites compared to the baselloy. There is a reduction in energy required for drillinghe composite compared to the base alloy since graphiteeing solid lubricant reduces the friction at tool–work inter-ace. Brown and Surappa (Brown and Surappa, 1988) studiedhe machinibility of Al–Si–graphitic particle composite andhey are under the opinion that the reduction in machiningorces with graphite reinforcement content is due mostly todecrease in the shear flow stress rather than to lower chip-

ake-face friction. Ground and polished as well as machinedurfaces of Al–Si alloy–graphite composites tend to be rougherhan similar surfaces on similar material without graphiteecause of deeper holes or valleys. Songmene and Balaz-

nzki (Songmene and Balazinzki, 1999) worked on drilling andilling of Al/SiCp, Al/SiCp–Gr and Al/Al2O3–Gr composite and

hey are under the opinion that the incorporation of graphitearticle into aluminium MMCs and the variation of hard par-icle content improve the machinibility of the composite. Theorque when drilling graphitic composites was comparable tohat of Al 380 aluminium alloy. Paulo Davim (Davim, 2003a,b)tudied the drilling of metal matrix composites based onaguchi technique to find the influence of cutting parametersn tool wear, torque and surface finish and the interactionsetween the above factors. He analyzed the data by analysis

f variance and found the percentage of influence of each fac-or on responses. Ramulu et al. (Ramulu et al, 2003) conductedxperiments by using PCD drills to drill Al2O3 particulateeinforced aluminium-based metal matrix composites. The

h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338 333

analysis of variance (ANOVA), response surface methodol-ogy was used to analyze experimental data and developedregression models. They concluded that drilling forces andaverage surface roughness values are greatly influenced bythe feed rate than the cutting speed. An extensive study onmachinibility of Al/SiCp and Al/Gr were carried out individu-ally. Traditionally graphite is a natural lubricant, which easesmachining. Little research has been done on the incorporationof graphite in SiCp composite.

In view of the above, an attempt has been made in thisinvestigation to study the effect of graphite on machinabil-ity of Al/SiCp composite. The Taguchi design of experimentsand analysis of variance were used to find the percentage ofinfluence of various factors and their interactions on drillingof both the composites.

2. Taguchi techniques

Taguchi technique is a powerful tool for the design of highquality systems (Taguchi and Konishi, 1987; Taguchi, 1993;Ross, 1988). It provides a simple, efficient and systematicapproach to optimize design for performance, quality andcost. The methodology is valuable when design parametersare qualitative and discrete. Taguchi parameter design canoptimize the performance characteristics through the settingof design parameters and reduce the sensitivity of the systemperformance to the source of variation (Ross, 1988; Roy, 1990).This technique is multistep process, which follow a certainsequence for the experiments to yield an improved under-standing of product or process performance. This design ofexperiments process made up of three main phases: the plan-ning phase, the conducting phase and analysis interpretationphase. The planning phase is the most important phase; onemust give a maximum importance to this phase. The datacollected from all the experiments in the set are analyzedto determine the effect of various design parameters. Thisapproach is to use a fractional factorial approach and this maybe accomplished with the aid of orthogonal arrays. Analysis ofvariance is a mathematical technique, which is based on leastsquare approach. The treatment of the experimental resultsis based on the analysis of average and analysis of variance(Davim, 2000, 2003a,b; Tsao and Hocheng, 2004).

3. Experimental

3.1. Materials

The matrix material used in the present investigation wasaluminium alloy Al2219 and its chemical composition (%) isSi = 0.2 max, Fe = 0.3 max, Cu = 5.8–6.8, Mn = 0.2–0.4, Mg = 0.02max, Zn = 0.1 max, V = 0.05–0.15, Ti = 0.02–0.1, Zr = 0.1–0.25,Al = balance. Two types of materials were used first with 15%of SiCp reinforcement of average particle size of 25 �m (whichcan be referred as M1 henceforth), second along with 15% sil-icon carbide particles, 3% graphite of average particles size

45 �m was used as the reinforcement materials (which can bereferred as M2 henceforth). The composites were fabricated bystir casting method, which was used by the other researchers(Hashim et al., 2002; Zhou and Xu, 1997; Seah et al., 1997).

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Table 1 – Summary of experimental conditions

Machine HardFord vertical CNC machining centerDrills Solid carbide multifaceted drill of

diameter 5 mm of typeR850-0500-30-A1A-N20D (SANDVIK)

Work piece (1) Al 2219/15% SiCp and (2) Al2219/15%

SiCp/3% Gr

Cutting conditions Speed 1000, 2000, 3000 rpm; feed rate 0.05,0.15, 0.25 mm/rev

3.2. Plan of experiments

For the plan of experiments, Taguchi method with two factorsat three levels were used. The levels of the spindle speed andfeed rate considered are as shown in the Table 1. Orthogonalarray of L9 (23) was chosen, which has nine rows correspond-ing to the number of tests (8 degrees of freedom) with fourcolumns at three levels (Ramulu et al, 2003; Davim, 2003a,b;Davim and Reis, 2003). This orthogonal array was chosen sinceit has capability to check the interactions among the factors.The factors and the interactions are assigned to the columns.The factors considered in the present study are cutting speed,feed rate and the responses to be studied are thrust force, sur-face finish and exit burr height. In the plan of experimentswith nine tests, the first column was assigned to the cuttingvelocity (V) and second column to the feed rate (F) and theremaining were assigned to the interactions.

3.3. Experimental procedure

Drilling tests were conducted on HardFord vertical CNCmachining center. The machining samples were prepared inthe form of 120 mm × 40 mm × 10 mm blocks for each material.The solid carbide multifacet drill bits of 5 mm diameter wereused. The brief summary of the experimental conditions were

shown in Table 1. The computer controlled data acquisitionsystem was used to collect and record the data of the exper-iments. The strain gauge based dynamometer was used torecord the thrust force. The experiments were repeated twice

Table 2 – ANOVA for thrust force for both the materials

Factor SS d.f. Variance

SiCp reinforced composite (M1)Feed 298256.1 2 149128.05Speed 711.25 2 355.63Error 180.5 13 13.88

Total 299147.9 17

SiCp–graphite reinforced composite (M2)Feed 154232.7 2 77116.3350Speed 242.5 2 121.2500Error 90.2 13 6.9385

Total 154565.4 17

SS: sum of squares, d.f.: degree of freedom.a 99% confidence level.b Percentage of contribution.

e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338

to circumvent the possible experimental errors. The surtronics3+ was used to measure the surface roughness of the drilledholes. The burr height was measured by using a height gaugewith least count 0.001 mm. The surface finish and burr heightare recorded at four different locations and the average resultsare considered for the analysis.

4. Results and discussions

4.1. Influence of the cutting parameters on the thrustforce

Thrust is the reaction force against the drill’s advance intothe work piece. The experimental results of thrust forcesas a function of cutting parameters in drilling of compos-ites as per orthogonal array are recorded and analysed. FromANOVA Table 2, one can observe that the most significantfactor for materials M1 and M2 is feed rate and it is 99%for both the materials hence it has a statistical and physi-cal significance. The cutting speed factor and the interactionsbetween cutting speed and feed rate for both composites donot have any physical and statistical significance and can beneglected. It can be observed from the mean response plotsof the analysis that very less thrust force was produced indrilling of graphitic composites compared to the SiCp rein-forced composites (Fig. 1). The feed rate is the predominantfactor and as the feed rate increases the thrust force increasesfor both the composites (Davim and Baptista, 2001; Morinet al., 1995). Ramulu et al. (Ramulu et al., 2002) were underthe opinion that regardless of the tool material and workmaterial, the thrust is highly dependent on feed rate whilecutting speed was found to have insignificant influence onthe degree of drilling forces. Charles Lane (Lane, 1993) wasunder the opinion that the feed rate was determined to bethe most significant parameter affecting the drill life and tool

forces. Increasing the feed rate increases cutting forces signif-icantly. Songmene and Balazinzki (1999) and Basavarajappa etal. (2007) reported the effect of graphite in Al/SiCp–Gr compos-ites. According to them, inclusion of graphite in the composite

F-test F-test (%) at 99%a pb

10740.52 8.60 99.6925.61 8.60 0.23

0.08

100

11114.33 8.60 99.7817.47506 8.60 0.15

0.08

100

j o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338 335

Fig. 1 – Response plots of the ANOVA analysis: (a) variation of thrust force vs. spindle speed and (b) variation of thrust forcev

hTtptumpa

4r

Tsfaicctari

s. feed rate.

as reduced the hardness and strength of the composite.hese are favorable for machinability. In the present case also

he reduction in thrust force when drilling graphitic com-osites can be observed, this indicates the positive effect ofhe graphite in the composite. This may be due to the nat-ral lubricant property of the reinforcement, which will easeachining. This helps in shearing the material along the shear

lane and influences in reducing the shear flow stress (Brownnd Surappa, 1988).

.2. Influence of cutting parameters on surfaceoughness

able 3 shows the results of the analysis of variance with theurface roughness for both the materials. One can observerom Table 3 that the feed rate (for material M1 is 53.53%nd that for M2 is 71.27%) and cutting speed factor (for M1s 44.17% and that for M2 is 23.62%) have statistical and physi-al significance on the surface roughness obtained for both theomposites. The statistical significance of interaction between

he factors is minimum and it can be neglected. The errorssociated is approximately 2.3 and 5.11% for M1 and M2,espectively. The surface roughness values are always increas-ng with increase in the feed rate and decreases with increase

Table 3 – ANOVA for surface finish for both the materials

Factor SS d.f. Variance

SiCp reinforced composite (M1)Feed 0.92 2 0.4600Speed 0.76 2 0.3800Error 0.03 13 0.0023

Total 1.71 17

SiCp–graphite reinforced composite (M2)Feed 0.92 2 0.4600Speed 0.31 2 0.1550Error 0.05 13 0.0038

Total 1.28 17

SS: sum of squares, d.f.: degree of freedom.a 99% confidence level.b Percentage of contribution.

in cutting speed and the results are in agreement with otherresearchers (Ramulu et al., 2002; Davim, 2003a,b; Davim andBaptista, 2001). From the mean response plots of the ANOVA(Fig. 2) the SiCp reinforced composites exhibiting lesser aver-age surface roughness values compared to SiCp–Gr reinforcedcomposites in both variation of cutting speed and feed rate. Itis clear from the figure that as the cutting speed increases thesurface finish will increase and decreases with increase in feedrate, however the material M2 shows higher roughness valuescompared to the material M1. The lowest surface roughnessvalues occurred at the lowest feed rate with highest cuttingspeed. The lower roughness values in the material M1 is maybe due to burnishing or honing effect produced by the rubbingaction of small SiC particles trapped between the flank faceof the tool and the workpiece surface (Monaghan and O’Reilly,1992; El-Gallab and Sklad, 1998; Tosun and Muratoglu, 2004;Basavarajappa et al., in press). The increase in surface rough-ness values with increase in feed rate is because of the moreserious built up edges on the tip of the drill with increase in thefeed rate (Ramulu et al., 2002). The higher surface roughness

values in the material M2 may be due to the release of graphitebetween the workpiece and flank face of the tool. This graphitewill reduces the friction and burnishing or honing effect thatcauses the increased surface roughness.

F-test F-test (%) at 99%a pb

199.33 8.60 53.53164.66 8.60 44.17

2.29

100

119.6 8.60 71.2740.3 8.60 23.62

5.11

100

336 j o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338

Fig. 2 – Response plots of the ANOVA analysis: (a) variation of surface finish vs. spindle speed and (b) variation of surfacefinish vs. feed rate.

Table 4 – ANOVA table for the burr height for both the materials

Factor SS d.f. Variance F-test F-test (%) at 99%a pb

SiCp reinforced composite (M1)Feed 0.41 2 0.205000 88.83 8.60 79.49Speed 0.07 2 0.035000 15.17 8.60 12.82Error 0.03 13 0.002308 7.69

Total 0.51 17 100

SiCp–graphite reinforced composite (M2)Feed 0.21 2 0.1050 136.5 8.60 63.17Speed 0.11 2 0.0550 71.5 8.60 32.87Error 0.01 13 0.0008 3.96

Total 0.33 17 100

SS: sum of squares, d.f.: degree of freedom.a 99% confidence level.b Percentage of contribution.

4.3. Influence of the cutting parameters on the burr

Burr is plastically deformed material generated on both theentry and exit of the hole. These burrs cause several problemsfor product quality and functionality as they can interface withassembly of parts and can cause jamming effect. The forma-tion of burrs at the end of a cut is similar to the formationof chips. From ANOVA Table 4 one can observe that the feedrate factor (for material M1 is 79.49% and that for materialM2 is 63.17%) has a statistical and physical significance onthe burr height obtained. The cutting speed factor for mate-

rial M1 is 12.82% and for M2 is 32.87%. The interaction effectsof cutting speed and feed rate for both materials do not havea physical and statistical significance. The errors associatedwith these are 7.69 and 3.96% for M1 and M2, respectively.

Fig. 3 – Burr formed on exit side of the holes runs at 2000 rpm anAl2219/15SiCp–3Gr (M2).

When the work material on the exit side becomes too weakto support the thrust force, partially deformed chips bend inthe direction of the cutting velocity at the end of the cut andburr forms at that point (Ramulu et al., 2002). Fig. 3(a) and (b)shows the photographs of the burr formation at the exit ofthe drilled hole for material M1 and material M2 at a cuttingspeed of 2000 rpm and at 0.15 mm/rev feed rate, respectively. Itcan be clearly observed from the response plots of the ANOVAanalysis in Fig. 4(a) and (b) that the burr height is increasedwith increase in feed rate predominantly and increase in burrheight with increase in cutting speed is less. This is mainly due

to the thrust force generated. It indicates that at higher cut-ting speed, burr height may slightly decrease. The formation ofburr in graphitic composite is less when compared to the SiCpcomposite. This may be due to the effect of graphite that helps

d 0.15 mm/rev: (a) Al2219/15SiCp (M1) and (b)

j o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338 337

Fig. 4 – Response plots of the ANOVA analysis: (a) variation of burr height vs. spindle speed and (b) variation of burr heightv

tc

5

Ticc

(

r

B

B

B

C

s. feed rate.

he material to shear easily and formation of discontinuouships during drilling of composites.

. Conclusions

he following conclusions can be drawn from the presentnvestigation on drilling of SiCp and SiCp–graphitic reinforcedomposites using solid carbide multifacet drills at differentutting parameters:

(i) Feed rate is the main factor, which is influencing thethrust force in both the composites. The cutting speedand its interactions with feed rate are minimum and canbe neglected. The incorporation of 3% graphite in Al/SiCpcomposite will reduce up to 25% of the thrust force for therange of parameters studied.

(ii) The surface finish increases with increase in cuttingspeed but decreases with increase in feed rate for both thecomposites. The graphitic composites show poor valuesof surface finish than SiCp reinforced composite.

iii) The significant factor for feed rate on burr formation is79.49% for M1 and is 63.17% for M2. The burr formationwhen drilling M2 is less than that of M1. The incorpora-tion of graphite in SiCp reinforced composites helps thematerial to shear easily and formation of discontinuouschip during the drilling of the composites.

e f e r e n c e s

asavarajappa, S., Chandramohan, G., Prabu, M., Mukund, K.,Ashwin, M., 2007. Drilling of hybrid metal matrixcomposites—workpiece surface integrity. Int. J. Machine ToolsManuf. 47, 92–96.

asavarajappa, S., Chandramohan, G., Paulo Davim, J., Prabu, M.,Mukund, K., Ashwin, M., Prasannakumar, M., Drilling ofhybrid aluminium matrix composites, Int. J. Adv. Manuf.Technol., in press.

rown, C.A., Surappa, M.K., 1988. The machinibility of a cast

aluminium alloy–graphitic particle composite. Mater. Sci. Eng.A 102, 31–37.

iftci, I., Turker, M., Sekar, U., 2004. Evaluation of tool wear whenmachining SiC-reinforced Al-2014 alloy matrix composites.Mater. Des. 25, 251–255.

Davim, J. Paulo, 2000. An experimental study of tribologicalbehaviour of the brass/steel pair. J. Mater. Process. Technol.100, 273–279.

Davim, J. Paulo, 2003a. Study of drilling metal matrix compositesbased on the Taguchi techniques. J. Mater. Process. Technol.132, 250–254.

Davim, J. Paulo, 2003b. Design optimization of cutting parametersfor turning metal matrix composites based on the orthogonalarrays. J. Mater. Process. Technol. 132, 340–344.

Davim, J. Paulo, Antonio, C.A. Conceicao, 2001. Optimal drilling ofparticulate metal matrix composites based on experimentaland numerical procedures. Int. J. Mach. Tools Manuf. 41, 21–31.

Davim, J.P., Baptista, A.M., 2001. Cutting force, tool wear andsurface finishing drilling metal matrix composites. Proc. Inst.Mech Eng. E 215, 177–183.

Davim, J. Paulo, Reis, P., 2003. Study of delamination in drillingcarbon fiber reinforced plastics (CFRP) using design ofexperiments. Compos. Struct. 59, 481–487.

El-Gallab, M., Sklad, M., 1998. Machining of Al/SiC particulatemetal matrix composites. Part II. Workpiece surface integrity.J. Mater. Process. Technol. 83, 151–158.

Goni, J., Mitxelena, I., Coleto, J., 2000. Development of low costmetal matrix composites for commercial applications. Mater.Sci. Technol. 16, 743–746.

Hashim, J., Looney, L., Hashmi, M.S.J., 2002. Particle distribution incast metal matrix composites Part-I. J. Mater. Process.Technol. 123, 251–257.

Ibrahim, I.A., Mohamed, F.A., Lavernia, E.J., 1991. Metal matrixcomposites—a review. J. Mater. Sci. 26, 1137–1157.

Lane, C., 1993. International conference on advanced compositematerials. In: Chandra, T., Dhingra, A.K. (Eds.), The Minerals,Metals and Materials Society, pp. 1113–1117.

Manna, A., Bhattacharya, B., 2003. A Study of machinability ofAl–SiC-MMC. J. Mater. Process. Technol. 140, 711–716.

Monaghan, J., O’Reilly, P., 1992. The drilling of an Al/SiCmetal-matrix composite. J. Mater. Process. Technol. 33,469–480.

Morin, E., Masounave, J., Laufer, E.E., 1995. Effect of wear oncutting forces in the drilling of metal matrix composites.Wear 184, 11–16.

Mubaraki, B., Bandyopadhyay, S., Fowle, R.F., Mathew, P., Heath,P.J., 1995. Drilling studies of an Al2O3-Al metal matrixcomposite. Part I. Drill wear characteristics. J. Mater. Sci. 30,6273–6280.

Ramulu, M.,Kim, D., Kao, H., 2003. Experimental study of PCD tool

performance in drilling (Al2O3)/6061 metal matrixcomposites, SME Technical Paper MR03-171, pp. 1–7.

Ramulu, M., Rao, P.N., Kao, H., 2002. Drilling of (Al2O3)p/6061metal matrix composites. J. Mater. Process. Technol. 124,244–254.

n g t

delamination associated with various drill bits in drillingof composite material. Int. J. Machine Tools Manuf. 44,

338 j o u r n a l o f m a t e r i a l s p r o c e s s i

Ross, P.J., 1988. Taguchi Technique for Quality Engineering.McGraw-Hill, New York.

Roy, K.R., 1990. A Primer on Taguchi Method. Van NostradReinhold, New York.

Seah, K.H.W., Sharma, S.C., Girish, B.M., 1997. Mechanicalproperties of as-cast and heat treated ZA-27/graphiteparticulate composites. Composite A 28A, 251–256.

Sharma, S.C., Girish, B.M., Kulkarni, R.S., Kamath, R., 1996.Drillabiliy of zinc/graphitic meal matrix composites. NMLTech. J. 38 (3), 107–111.

Sinclair, I., Gregson, P.J., 1997. Structure performance of

discontinuous metal matrix composites. Mater. Sci. Technol.13, 709–715.

Songmene, A.V., Balazinzki, M., 1999. Machinibility of graphiticmetal matrix composites as a function of reinforcingparticles. CIRP 48 (1), 77–80.

e c h n o l o g y 1 9 6 ( 2 0 0 8 ) 332–338

Taguchi, G., 1993. Taguchi on Robust Technology DevelopmentMethods. ASME Press, New York, 1–40.

Taguchi, G., Konishi, S., 1987. Taguchi methods, orthogonal arraysand linear graphs. In: Tools for Quality Engineering. AmericanSupplier Institute, pp. 35–38.

Tosun, G., Muratoglu, M., 2004. The drilling of Al/SiCp metalmatrix composites. Part II. workpiece surface integrity.Compos. Sci. Technol. 64, 1413–1418.

Tsao, C.C., Hocheng, H., 2004. Taguchi analysis of

1085–1090.Zhou, W., Xu, Z.M., 1997. Casting of SiC reinforced metal matrix

composites. J. Mater. Process. Technol. 63, 358–363.