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Journal of Alloys and Compounds 662 (2016) 325e338

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Journal of Alloys and Compounds

journal homepage: http: / /www.elsevier .com/locate/ ja lcom

An analysis of mechanical properties and optimization of EDM processparameters of Al 4032 alloy reinforced with Zrb2 and Tib2 in-situcomposites

N.V. Rengasamy a, M. Rajkumar b, *, S. Senthil Kumaran c

a Department of Mechanical Engineering, Anna University, Chennai, 620005, Tamilnadu, Indiab Department of Mechanical Engineering, RVS College of Engineering, Dindigul, 624005, Tamilnadu, Indiac Research and Development Centre, Department of Mechanical Engineering, RVS Educational Trust's Group of Institutions, RVS School of Engineering andTechnology, Dindigul, 624005, Tamilnadu, India

a r t i c l e i n f o

Article history:Received 27 November 2015Accepted 7 December 2015Available online 12 December 2015

Keywords:Aluminum matrix compositesElectrical discharge machining (EDM)Mechanical propertiesTaguchi methodANOVA

* Corresponding author.E-mail addresses: renga1973renga@gmail.com (N

gmail.com (M. Rajkumar), sskumaran@ymail.com (S.

http://dx.doi.org/10.1016/j.jallcom.2015.12.0230925-8388/© 2015 Elsevier B.V. All rights reserved.

a b s t r a c t

In the present study, the new engineered metal matrix composites (MMC) Aluminum 4032 is reinforcedwith reinforcement particles Zrb2 and Tib2 in various Wt. % (0,2,4,6,8) at room temperature through thestir casting method. The reinforcement particles Zrb2 (Zirconium Boride) and Tib2 (Titanium Boride)influences the mechanical property and parameters such as material removal rate, tool wear rate anddepth in EDM machining process. Initially, the mechanical property such as tensile, compressive andhardness value has been measured for the Al 4032 composite alloy and it proves that increase in me-chanical strength is due to the increase in reinforcement particles. Electrical discharge machining (EDM)is carried out on the composite alloy Al 4032 with tool as copper electrode where input parameters suchas Pulse ON, (mS) Pulse OFF (mS) Current (Amps) is provided initially to set up the machining process. Toidentify the optimize process parameter in EDM machining process which influence to obtain minimummaterial removal rate (MRR), tool wear rate (TWR) and depth (Depth), the Taguchi L25 orthogonal array isused. The analysis of variance (ANOVA) was used to investigate the percentage of contribution by eachparameter. The variation of current (amps), Pulse ON, Pulse OFF of the Al 4032 composite have beenmeasured with the function of three parameter such as MRR, TWR and depth.

© 2015 Elsevier B.V. All rights reserved.

1. Introduction

The property such as low density, high specific strength andspecific stiffness are in-corporatized in metal matrix composites.The metal matrix composites are good resistance to abrasion,temperature and impact as well as good shock absorption, gooddimensional stability and casting. These advantages contribute tothe wide acceptance of aluminum matrix composites in high-technology structural and functional applications in fields such asmining, aerospace, automotive, defense, electronic industries,sports and recreation [1,2]. MMC's have to chemically and physi-cally distinct phases. Which are distributed to provide propertieswhich are not obtainable either of the individual phases [3]. MMC'sare produced in a different way of conventional metal alloying.

.V. Rengasamy), vathilairaj@Senthil Kumaran).

These composites are produced by combining two preexistingconstituents [4]. In this investigation, the reinforced particles suchas Zrb2 and Tib2 in variousWt. % (0,2,4,6,8) is mixedwith thematrixalloy Al 4032 to form composite alloy through in-situ process. Thereinforced particles Zrb2 and Tib2 are formed by the mixing of threesalts such as of K2ZrF6, k2TiF6 and KBF4. These particles posses highreinforcement for composites has both physical and mechanicalstrength. Here electrical discharge machining (EDM) is used to drillhole on the upper surface of the specimen. In total, around twentyfive specimens are made in desired shape and size of copper elec-trode is used to conduct this experiment. The mechanical propertysuch tensile, compressive and hardness value has been measuredby conducting various test according to the ASTM standards. Theinput parameter assigned in EDM process such as Pulse ON, (mS)Pulse OFF (mS), Current (Amps) is used to measure the outputparameter such as material removal rate (MRR), tool wear rate(TWR) and depth (Depth) with function of composites in variousWt. %. The Taguchi L25 orthogonal array has been used to identify

Fig. 1. Work piece made up of Aluminum 4032 composite alloy.

Fig. 2. EDM machine setup.

Fig. 3. Tool e copper electrode.

Table 2Shows the properties of electrode material.

S. No Properties Value

1 Melting point (�C) 1083

2 Elastic modulus(E) (N/mm2) 1.23 � 105

3 Poisson's ratio 0.264 Density (gm/cm3) 8.9

N.V. Rengasamy et al. / Journal of Alloys and Compounds 662 (2016) 325e338326

the most influential process parameter and find out the minimumMRR, TWR and Depth value for the composite alloy Al 4032. TheAnalysis of variance (ANOVA) is used to obtain the total percentageof contribution of each parameter in MRR, TWR and Depth. Thevariation of current (amps), Pulse ON, Pulse OFF of the Al 4032composite alloy is measured as a function of MRR (g/min), TWR (g/min) and Depth (g/min) in composite alloy with various Wt. % ofreinforcement.

2. Experimental details

2.1. Material selection

In this investigation, the matrix material Al 4032 is consideredas the base material were combined with reinforcement particlessuch as Zrb2 and Tib2 in various Wt. % to form the Al 4032 com-posite alloy. The reinforcement particle such as Zrb2 and Tib2 areinitially formed separately by mixing of three salts such as K2ZrF6,k2TiF6 and KBF4 in appropriateWt. %. The composite alloy Al 4032 ismade by adding the Al 4032 matrix material with reinforcementparticles in various Wt. % (0,2,4,6,8) to form a five different set ofwork pieces. The chemical composition of Al 4032 alloy withvariousWt. % is shown in the Table 1. Thematrix material Al 4032 ismixed with the reinforcement particles Zrb2 and Tib2 to expose thestrength of mechanical properties of in-situ composites in variousweight percentages from its standard consideration.

2.2. Work piece design

The stir casting method is used in this study to prepare the workpiece for this experiment. Thework piece is prepared by themixingof matrix alloy Al 4032 with reinforcement particles such as Zrb2and Tib2 in various Wt. % (0,2,4,6,8). The work piece made up ofAluminum 4032 with reinforcement particle is shown in Fig. 1. Inthe process of stir casting method, it poses a crucible made up ofgraphite, in which the matrix material Al 4032 is taken along withthe reinforcement particles in various Wt. % (0,2,4,6,8) is poured into and heated to a temperature of 850 �C, which forms an moltenmetal. This molten metal is stirred well to make the particles todistribute even in all above the surface with an aid of stirrer. Thechemical reaction between the inorganic salts and the molten Altook place to form in situ particulates [5]. Finally, the molten metalis transferred in to themold is made in the shape of cylindrical withdiameter of 10mm and length of 25mm. This mold is done to parchand the work piece is detached to obtain desired shape and sizethrough turning and facing operations.

2.3. EDM machining process

The EDM is a manufacturing method where a work piece ismade in accurate shape and size through electric discharge sparks.In this study, the twenty five specimens are considered with size ofdiameter 10 mm and length 25 mm for the EDM process. Theprocess is carried out in an AC power supply of 415 V and keroseneis considered as a di-electric fluid as it posses low chemical reac-tivity. The electric discharge machine along with setup is shown inFig. 2. The copper electrode is used as tool for this process shown inFig. 3 and the Table 2 show the properties of tool e copper

Table 1Chemical composition of Al 4032 alloy in Wt. %.

Element Si Cu Mg Ni Fe Cr Zn Al

Wt% 11e13.5 0.5e1.3 0.8e1.3 0.5e1.3 1.0 max 0.10 max 0.25 max Bal

Fig. 5. Vickers hardness testing machine.

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electrode.Initially, the copper electrode tool and the specimen are fully

immerged in the di-electric kerosene fluid. The machine is setup toproduce a hole of 8 mm through drilling operation on the uppersurface of the specimen. The machining time was fixed in thecontrol panel for about 2 min. The composite alloy Al 4032 withvariousWt. % of reinforcement particles are subjected tomachiningis placed in the machining table. The work piece and electrode aremeasured before and after the machining process to calculate theMRR and TWR. All the preliminary setup has been made and powersupply is applied to the EDM machine. The power supply producesan electrical discharge sparks between the specimen and the tool.The high potential sparks are generated when the electrode aremoved closely to each other. Themachining is carried out as per thesetup, tool moves and removes the material as per the instructionand finishes the specimen once it reaches it time. As more heat isgenerated due to the high potential sparks, these sparks makes thespecimen to melt when it attains the melting point. The current ispassed between these sparks to avoid the excess heat. The Pulse ONtime is a particular duration time of current is passed. Fig. 4 showsthe machining for twenty five specimens is completed. Once themachining is done, the time is measured for the completing theprocess.

2.4. Vickers hardness test

The hardness value for the matrix alloy with reinforcementparticles such as Zrb2 and Tib2 in different (0,2,4,6,8) Wt. % arecalculated using the micro hardness testing machine carried out inroom temperature. The Vickers hardness testing machine is shownin Fig. 5. This test is performed on the methodically prepared pol-ished samples of composites and conducted according to the ASTME10-07 standards. Individual sample from every grouping is sub-jected to hardness test at various positions with applied load of0.5 kg for the interval of 25 s. The hardness is calculated at differentlocations is to obtain the average hardness value for every sampleand to evade the possibility of indenter position on the hard rein-forcement particles.

2.5. Tensile test

The ultimate tensile strength for the in-situ composite alloy isevaluated through the universal testing machine at room temper-ature. This tensile test is carried out as per the ASTM EO8-8 stan-dard. The composite alloy Al 4032 is made in to five groups of workpieces with five samples in each group is subjected to tensilestrength with condition of load of 10 KN is acted on the work piecewith constant time interval of 2.5 m/min of cross head speed. Thetensile properties of composite materials are a burly purpose innature and properties of reinforcing elements and matrix material.

Fig. 4. Specimen after EDM process.

2.6. Compression test

The matrix material Al 4032 with reinforcement particle Zrb2and Tib2 in various (0,2,4,6,8) Wt. % are made in to various set ofsamples to measure the compressive value of the composite alloyby means of the compressive test. The computerized universaltesting machine (UTM) is used in this study to carry out thecompression test according to the ASTM E9-09 standards. Whenthe samples are subjected to compressed, squashed, crushed orflattened, it shows the various fundamental behavior under acompressive load. These include the elastic limit, whichmaterials isapproximately equal to the proportional limit, and also known asyield point or yield strength, young's Modulus and compressivestrength [6].

2.7. Formula for calculating mrr and twr

The arithmetic standard formula is used to calculate the mate-rial removal rate (MRR) and tool wear rate (TWR). The materialremoval rate is calculated by the weight difference of before andafter machining of the work piece carried out per minute. The toolwear rate is calculated by measuring the weight difference ofelectrode which is subjected to machining before and after perminute [7]. The formula to calculate material removal rate and toolwear rate is shown in Equation (1) and Equation (2) respectively.

MATERIAL REMOVAL RATE ðMRRÞ ¼�Wi �Wf

�

ðtÞ [1]

Where,

MRR e Material Removal Rate (gms/min)MRR e Material Removal Rate (gms/min)Wf e Final weight of work piece (after machining) (gms)t e Period of trial (mins)

TOOL WEAR RATE ðTWRÞ ¼�Ti � Tf

�

ðtÞ [2]

Where,

TWR e Tool wear rate (gms/min)Ti e Initial weight of work piece (before machining) (gms)Tf e Final weight of work piece (after machining) (gms)t e Period of trial (mins)

3. Optimization techniques

In the present investigation, the two optimization techniques is

N.V. Rengasamy et al. / Journal of Alloys and Compounds 662 (2016) 325e338328

used to obtain the optimize results. The Two techniques used in thisinvestigation are Taguchi and ANOVA method. The optimized re-sults for minimum tool wear rate, material removal rate and depthof cut of Al 4032 composite alloy is determined.

3.1. Taguchi method

Taguchi method is an efficient problem solving tool, which isimprove the performance of the process, system, design andproduct with significantly reduced experimental time and cost [8].In this method, the term ‘signal’ represents the desirable value(mean) for the output characteristic and the term ‘noise’ representsthe undesirable value (standard deviation) for the output charac-teristic. This method uses the signal to noise ratio is to measure thequality characteristic deviating from the desired value [8]. There-fore, the signal to noise ratio (S/N) is the mean to the standarddeviation. Taguchi classifies objective function into three cate-gories, such as smaller the better type, larger the better type,nominal the best type [9,10]. In this method, Taguchi smaller thebetter type method is preferred to analyze the process parameters.The L25 orthogonal array has been used for this study. It provides anorthogonal array to study about the entire process parametersspace with small number of experiments [11]. The four importantinput parameters have been considered for this process, Compos-ites in various Wt. %, Pulse ON, Pulse OFF, Current. The values areconsigned to these factors have been shown below in the Table 3.The format of L25 orthogonal array is presented in Table 4.

3.2. Anova method

ANOVA is the statistical treatment most commonly applied tothe results of experiments to determine the percentage contribu-tion of each parameter. ANOVA helps in formally testing the sig-nificance of all main factors and their interactions by comparing themean square against an estimate of the experimental errors atspecific confidence levels [12,13]. In this study, optimal tool wearrate, material removal rate and depth of cut of the Al 4032 com-posite alloy is determined through the standard ANOVA proceduresusing the mean values. The calculated percentage of contributionby each parameter which influences the effect in tool wear rate,material removal rate and depth of the composite is obtained bymeans of ANOVA method.

4. Results and discussions

4.1. Mechanical properties of al 4032 composite

The matrix material Al 4032 with reinforcement particle Zrb2and Tib2 in various Wt. % (0,2,4,6,8) is subjected to determine themechanical properties such as tensile, compression and hardness atroom temperature according to the ASTM standard. The compositealloy with higher reinforcement particles proves that mechanicalproperties acquire greater hardness and strength value in all threeexaminations. The increase in strength and harness value is mainly

Table 3L25 Orthogonal array factors and levels.

Factor Levels

1 2 3 4 5

COMPOSITES (Wt. %) 0 2 4 6 8PULSE ON (TON) (mS) 6.2 6.4 6.6 6.8 7.0PULSE OFF(TOFF) (mS) 4 5 6 7 8CURRENT (Amps) 22 24 26 28 30

occurred due to the uniform distributed of particles due to highstring concentration and grain size of the composites in decreaseddue to the increase in string speed.

4.1.1. Tensile strengthThe tensile test is carried out for the matrix material Al 4032

with reinforcement particles such as Zrb2 and Tib2 in various Wt. %(0,2,4,6,8) in universal testing machine according to the ASTMstandard. The samples are subjected to tensile test in five differentWt. % and it confirms that matrix material with higher reinforce-ment particles has higher ultimate tensile strength when comparedwith minimum Wt. % of reinforcement particles. Fig. 6 shows theultimate tensile strength of Al 4032 with reinforcement particles invarious Wt. %. In general, the tensile properties of composite ma-terial posses a high function of quality and properties of reinforcingparticles and matrix material. The enhancement of mechanicalproperty tensile strength is achieved mainly due to the function ofmatrix and reinforcement materials. It may be noted that uniformdistribution of reinforcement coupled with reaction free interfacebetween matrix and reinforcement facilitates efficient transfer ofload from matrix to reinforcement. Thus, stress required for initi-ation of crack at the interface is enhanced [14]. The addition ofreinforcement particle Zrb2 to matrix material in Wt. % attains twodifferent states. In which it increases the volume fraction of thematerial and due to the increase in volume fraction, the elongationis developed between the grain boundaries. The size and shape ofthe reinforcement also dictates the tensile strength of composites.The improvement in ultimate tensile strength of developed com-posites is attributed to the fine size and cubical shape of Tib2 par-ticles formed in situ [15].

4.1.2. Compression strengthThe matrix material Al 4032 with its reinforcement particles

Zrb2 and Tib2 in various Wt. % is subjected to the compression testthough computerized universal testing machine at room temper-ature. The ultimate compressive strength is high due to the rein-forcement particles act as a second phase and resist the movementof dislocation in the matrix composite [16]. The ultimatecompression strength of Al 4032 matrix material with reinforcedparticles Zrb2 and Tib2 particles in Wt. % is shown in Fig. 7. Thecompressive strength is increased with increase in reinforcementparticles added to the matrix material in various volume fractions.The reinforcement particles help to prevent the dislocation ofbonding under load, but when the intense load is appliedmore. Themovement of dislocation is possible at higher stress levels will berequired to move through matrix phase. Hence more loads arerequired for nucleation of voids and their propagation leading tohigher compressive strength of the composites [17,18].

4.1.3. Microhardness testThe Vickers hardness testing machine is used to measure the

micro hardness value of the matrix alloy Al 4032 with reinforce-ment particles such as Zrb2 and Tib2 in various Wt. % at roomtemperature. It proves that the addition of reinforcement particlesdelivers a significant improvement in hardness value. The hardnessvalue of Al 4032 matrix composites reinforced by the Zrb2 and Tib2particles with different particle volume fraction is shown in Fig. 8.The addition of reinforcement particle Zrb2 initiates to increase inhardness value by developing a strong boundary between theparticles and matrix, which allows relocating and distribution ofload from the matrix to the particles and also the increase incomposite hardness due to its fine particulate distribution [19]. Tib2being a hard reinforcement, it renders the inherent property ofhardness to thematrix material, thereby enhancing its resistance todeformation [20]. The various reasons in achieving an higher

Table 4Experimental layout of L25 orthogonal array.

Experiment number Input parameters

Composites (wt. %) Pulse on (TON) (mS) Pulse off (TOFF) (mS) Current (amps)

1 0 6.2 4 222 0 6.4 5 243 0 6.6 6 264 0 6.8 7 285 0 7.0 8 306 2 6.2 5 267 2 6.4 6 288 2 6.6 7 309 2 6.8 8 2210 2 7.0 4 2411 4 6.2 6 3012 4 6.4 7 2213 4 6.6 8 2414 4 6.8 4 2615 4 7.0 5 2816 6 6.2 7 2417 6 6.4 8 2618 6 6.6 4 2819 6 6.8 5 3020 6 7.0 6 2221 8 6.2 8 2822 8 6.4 4 3023 8 6.6 5 2224 8 6.8 6 2425 8 7.0 7 26

Fig. 6. Ultimate tensile strength of Al 4032 composite alloy.

Fig. 7. Ultimate compressive strength of Al 4032 composite alloy.

Fig. 8. Hardness value of Al 4032 composite alloy.

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hardness value of composite alloy is due to the addition of rein-forcement particles which creates an better bonding among the

grain structure and the grain refinement of matrix material. Thesignificant level of bonding between the matrix material andreinforcement is the foremost factor in deciding the enhancementof hardness value of composite materials. It is an experimentallyproven fact that whenever a hard reinforcement is incorporatedinto a soft ductile matrix, the hardness of the matrix material isenhanced [21].

4.2. Optimization technique e taguchi method

In this experiment, the matrix material Al 4032 is reinforcedwith the two particles such as Zrb2 and Tib2 in various Wt. %(0,2,4,6,8). The input parameter such as composites (Wt. %), PulseON (TON), Pulse OFF (TOFF), Current (Amps) were considered as theinput parameter. The optimal result could be generated out Taguchimethod by means of systematic analysis of data and the dominantfactor involved in optimization [22]. The output parameter such asMRR (g/min), TWR (g/min) and Depth (g/min) has been calculatedthrough drilling operation for a constant time interval of 2 min per

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hole. This test has been carried out for twenty five pieces with fiveset of work pieces with each posing a various Wt. % of composites.The Table 5 shows the Input and output parameters of compositealloy according to L25 orthogonal array. The minimum materialremoval rate, tool wear rate, and depth are obtained value about0.190 (g/min), 0.005 (g/min) and 2.155 (g/min) from the inputparameter value of about 8W t. % composites, Pulse ON (TON), PulseOFF(TOFF) and Current of about 7.0 (mS), 7 (mS), 26 (Amps)respectively.

4.2.1. Signal-to-noise ratioIn this study, the MRR, TWR and Depth are the main charac-

teristics considered in this investigationwhich influences about thequality of composites in various Wt. %. The software MINITAB wasused to calculate the influence of process parameters on variousresponses. The study has been done according to the L25 orthogonalarray and the input and output parameters are shown in Table 5.The response table for means and S/N ratio is shown in the Table 6and Table 7 respectively. The decisive factor smaller than better isused to choose the S/N ratio. The mean effect and S/N ratio forminimum wear rate of the composite alloy were calculated bystatistical software. Fig. 9 and Fig. 10 are the main effect plots formeans and S/N ratio respectively.

From the result obtained from S/N ratio, the composite invarious Wt. % influences in obtaining the minimumMRR, TWR andDepth. The parameter composite Wt. % is followed by the Pulse ON,Current and Pulse OFF. This is mainly due to the amount of rein-forcement particles added to the matrix alloy which composes thehigh mechanical properties. This makes the composite alloy morerigid and hard to its structure. The minimumwear will be obtainedin all composite alloys with higher enhancement of the reinforce-ment particles.

4.2.2. Analysis of variance (ANOVA) - material removal rateANOVA is the statistical treatment most commonly applied to

the results of experiments to determine the percentage contribu-tion of each parameter. ANOVA helps in formally testing the

Table 5Input and output parameters of composite alloy according to L25 orthogonal array.

Experiment number Input parameters

Composites (wt. %) Pulse on (TON) (mS) Pulse off (TOF

1 0 6.2 42 0 6.4 53 0 6.6 64 0 6.8 75 0 7.0 86 2 6.2 57 2 6.4 68 2 6.6 79 2 6.8 810 2 7.0 411 4 6.2 612 4 6.4 713 4 6.6 814 4 6.8 415 4 7.0 516 6 6.2 717 6 6.4 818 6 6.6 419 6 6.8 520 6 7.0 621 8 6.2 822 8 6.4 423 8 6.6 524 8 6.8 625 8 7.0 7

significance of all main factors and their interactions by comparingthe mean square against an estimate of the experimental errors atspecific confidence levels [23]. The software MINITAB is used tocalculate the percentage contribution of each process parameter toobtain the minimum material removal rate [24]. The results ob-tained using ANOVA is shown in the Table 8. Theminimummaterialremoval value is obtained is mainly influenced by the processparameter composites with reinforcement particles. The additionof higher reinforcement particles to the Al 4032 matrix alloy pro-cess that it posses higher strength and hardness to its structure,hencematerial removal is less when comparedwith lowaddition ofreinforcement particles. The calculated percentage of significancesthe important process parameter is composites (81.53%) followedby Pulse ON (8.72%) and Pulse OFF (4.26%). The interaction plot ofmean for material removal rate and respective percentage ofcontribution are graphically represented in Fig. 11 and Fig. 12respectively. Table 9. Shows the percentage of contribution foreach parameter.

4.2.3. Analysis of variance (ANOVA) e tool wear rateANOVA is the statistical treatment most commonly applied to

the results of experiments to determine the contribution of eachprocess parameter. The same above method is pursued to find outthe parameter that influences the tool wear rate. The results ob-tained using ANOVA for tool wear rate is shown in the Table 10. Thetool wear rate (TWR) is influenced mainly due to the processparameter composites in Wt. %. The tool wear rate is minimummainly due to the influence of composites with its reinforcementadded in various Wt. %. As the specimen posses more strength andhardness, the material removal rate is minimum. Hence due to theminimum removal rate, the tool wear rate is minimum due to thecomposites in various wt. %. The material removal rate and toolwear rate is directly proportional to each other. The importantcalculated process parameter in percentage of contribution iscomposites of about (80.46%) and next is Pulse ON (8.59%) andPulse OFF (2.34%). The interaction plot of mean for tool wear rate isshown in Fig. 13. The respective percentage of contribution is

Output parameters

F) (mS) Current (amps) MRR (g/min) TWR (g/min) Depth (g/min)

22 0.770 0.015 4.82024 0.660 0.015 4.62026 0.505 0.010 4.53528 0.490 0.010 4.43530 0.480 0.010 4.42526 0.465 0.010 4.12228 0.425 0.010 3.58530 0.415 0.010 3.41022 0.400 0.010 3.39524 0.390 0.010 3.23030 0.375 0.010 3.22022 0.355 0.005 3.19324 0.350 0.005 3.16526 0.350 0.005 3.11028 0.330 0.005 3.09624 0.325 0.005 2.95526 0.315 0.005 2.80528 0.310 0.005 2.53530 0.305 0.005 2.49522 0.285 0.005 2.47528 0.280 0.005 2.46530 0.250 0.005 2.30022 0.250 0.005 2.23524 0.240 0.005 2.16526 0.190 0.005 2.155

Table 6Response table for means.

Level Composites (Wt. %) Pulse on (TON) (mS) Pulse off (TOFF) (mS) Current (amps)

1 1.72000 1.32280 1.20700 1.214532 1.32580 1.23653 1.24120 1.209333 1.17160 1.18300 1.19000 1.239134 0.98867 1.16133 1.19720 1.199075 0.83700 1.13940 1.20767 1.18100DELTA 0.88300 0.18340 0.05120 0.05813RANK 1 2 4 3

Table 7The response table for S/N ratio.

Level Composites (Wt. %) Pulse on (TON) (mS) Pulse off (TOFF) (mS) Current (amps)

1 �8.48795 �5.96851 �5.10016 �5.139342 �6.25882 �5.42220 �5.35844 �5.211483 �5.26644 �5.05838 �5.07721 �5.462344 �3.73981 �4.89784 �5.23136 �5.237225 �2.36519 �4.77128 �5.35103 �5.06782DELTA 6.12276 1.19723 0.28122 0.39452RANK 1 2 4 3

Fig. 9. Main effect plots for means.

Fig. 10. Main effect plot for S/N ratio.

Table 8The results obtained from ANOVA e Material removal rate.

Source DF Seq.SS Adj.SS Adj.MS F P Percentage of contribution

COMPOSITES (Wt. %) 4 0.334666 0.334666 0.083666 38.24 0.000 81.53PULSE ON (TON) (mS) 4 0.035796 0.035796 0.008949 4.09 0.043 8.72PULSE OFF (TOFF) (mS) 4 0.013426 0.013426 0.003357 1.53 0.281 3.27CURRENT (Amps) 4 0.017502 0.017502 0.002188 1.03 0.446 4.26Error 8 0.009056 0.009056 0.002264 2.20Total 24 0.410446

Seq. SS, Sequential sum of squares; Adj. SS, adjusted sum of squares; Adj. MS, adjusted mean squares; F. statistical test; P. statistical value.

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graphically represented in Fig. 14. The percentage of contribution

for each parameter is shown in Table 11.

Fig. 11. Interaction plot e data means for material removal rate.

Fig. 12. Percentage of contribution for process parameter e Material removal rate.

Table 9Percentage of contribution for each parameter.

Factors Percentage of contribution (%)

COMPOSITES (Wt. %) 81.53PULSE ON (TON) (mS) 8.72PULSE OFF (TOFF) (mS) 3.27CURRENT (Amps) 4.26

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4.2.4. Analysis of variance (ANOVA) e DEPTHThe analysis of variance (ANOVA) is used to identify the

contribution of each process parameter in the depth of cut. Theresults obtained using ANOVA for depth is shown in the Table 12. Inidentifying the influence of process parameter in depth, the drillingoperation is made on the upper surface of the composites specimen

at various locations at a time interval of 2 min per operation withvarious input parameters. The depth of cut is measured in all lo-cations to average the depth values. The minimum value isobserved in higher amount of reinforcement particles in matrixalloy Al 4032 and also this paper proves that material removal rateand tool wear rate is minimum at higher reinforcement Wt. %.Hence the value of depth of cut is minimum mainly due to theinfluence of composites in various Wt. %. The important calculatedprocess parameter in percentage of contribution is composites ofabout (94.95%) and next is Pulse ON (3.76%) and Pulse OFF (0.50%).The interaction plot of mean for depth is shown in Fig. 15. Therespective percentage of contribution is graphically represented inFig. 16. The percentage of contribution for each parameter is shownin Table 13.

Table 10The results obtained from ANOVA e Tool wear rate.

Source DF Seq.SS Adj.SS Adj.MS F P Percentage of contribution

COMPOSITES (Wt. %) 4 0.0002060 0.0002060 0.0000515 18.73 0.000 80.46PULSE ON (TON) (mS) 4 0.0000220 0.0000220 0.0000027 1.45 0.302 8.59PULSE OFF (TOFF) (mS) 4 0.0000060 0.0000060 0.0000015 0.55 0.708 2.34CURRENT (Amps) 4 0.0000160 0.0000160 0.0000040 0.55 0.708 6.25Error 8 0.0000060 0.0000060 0.0000015 2.34Total 24 0.0002560

Seq. SS, Sequential sum of squares; Adj. SS, adjusted sum of squares; Adj. MS, adjusted mean squares; F. statistical test; P. statistical value.

Fig. 13. Interaction plot e data means for tool wear rate.

Fig. 14. Percentage of contribution for process parameter e Tool wear rate.

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Table 11Percentage of contribution for each parameter - Tool wear rate.

Factors Percentage of contribution (%)

COMPOSITES (Wt. %) 80.46PULSE ON (TON) (mS) 8.59PULSE OFF (TOFF) (mS) 2.34CURRENT (Amps) 6.25

Table 12The results obtained from ANOVA e Depth.

Source DF Seq.SS Adj.SS Adj.MS F P Percentage of contribution

COMPOSITES (Wt. %) 4 15.8004 15.8004 3.9501 377.92 0.000 94.95PULSE ON (TON) (mS) 4 0.6269 0.6269 0.1567 14.99 0.001 3.76PULSE OFF (TOFF) (mS) 4 0.0835 0.0835 0.0209 1.10 0.417 0.50CURRENT (Amps) 4 0.0836 0.0836 0.0105 2.00 0.188 0.50Error 8 0.0462 0.0462 0.0115 0.27Total 24 16.6406

Seq. SS, Sequential sum of squares; Adj. SS, adjusted sum of squares; Adj. MS, adjusted mean squares; F. statistical test; P. statistical value.

Fig. 15. Interaction plot e data means for depth.

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4.3. Investigation of wear properties

4.3.1. Variation of current (amps) as a function of MRR (g/min),TWR (g/min) and DEPTH (g/min)

In this investigation, the input parameter current (amps) isinfluencing the output parameter MRR, TWR and depth toobtaining a minimum value with effect of composite in various Wt.% of reinforcement particles. Fig. 17 shows the variation of current(amps) with material removal rate. The current is supplied atvarious set of values of 22, 24, 26, 28 and 30 amps during the EDMprocess. In total, five different set of specimen is considered for thisinvestigation. This proves that, thematerial removal is maximum inall set of work piece at 0% of reinforcement particles and it de-creases gradually as the amount of reinforcement particles in-creases in its Wt. % with material alloy Al 4032. The composite alloyposses a high hardness value of the specimen will be the governaspect affecting removal rate. This mainly happens due to thepresence of Zrb2 and Tib2 particles with matrix alloy in various Wt.% which brings out the minimum loss.

Fig. 18 shows the variation of current (amps) with tool wear rate(g/min). According to the variation graph, the composite Wt. % of 0,2 posses higher tool wear rate and it is decreased steadily and re-mains same for all other Wt. % of composites (4,6,8). The variationof current (amps) with Depth (g/min) is shown in Fig. 19. It impliesthe same as the material removal rate as depth of cut is reducedgradually as increase in Wt. % of reinforcement particles with ma-

trix alloy. The depth of cut is measured by placing a drilling oper-ation on the work piece and material removal rate are directlyproportional to each other. The presence of Zrb2 and Tib2 particlesattributed to higher hardness of the composites and good interfa-cial bonding between the matrix and reinforcement, both of whichenhance the capacity of the final composite [25].

4.3.2. Variation of pulse on (TON) (mS) as a function of MRR (g/min),TWR (g/min) and DEPTH (g/min)

The variation between the Pulse ON (mS) as a function of MRR,TWR and depth accordance with composites in various Wt. % ismeasured. The value of the input parameter pulse ON is provided as6.2, 6.4, 6.6, 6.8 and 7.0 mS are supplied during the EDMprocess. Thevariation of Pulse ON (mS) with MRR (g/min) is shown in Fig. 20. Itimplies that the value of material removal rate is decreased as theamount of reinforcement particles is increased with the Matrixalloy Al 4032 in all set of specimen. The input parameter Pulse on issupplied as a time factor in which machining of the specimen to becarried out. During the process, the machining process becomes

Fig. 16. Percentage of contribution for process parameter e Depth.

Table 13Percentage of contribution for each parameter - Depth.

Factors Percentage of contribution (%)

COMPOSITES (Wt. %) 94.95PULSE ON (TON) (mS) 3.76PULSE OFF (TOFF) (mS) 0.50CURRENT (Amps) 0.50

Fig. 17. Variation of current (amps) with MRR (g/min).

N.V. Rengasamy et al. / Journal of Alloys and Compounds 662 (2016) 325e338 335

faster after increasing the pulse on time. By increasing the pulse ontime the material removal rate increase and poor surface finish onthe material surface [26]. The variation of Pulse ON (mS) with TWR(g/min) is shown in Fig. 21. The tool wear rate is maximum at basematerial; the, the TWR decreases gradually and fluctuates over theincrease inWt. % of reinforcement particles. TheWt. % of (4,6,8) hassame value tool wear rate in all set of specimen. Fig. 22 shows thevariation of Pulse ON (mS) with Depth (g/min). The characterizes ofmaterial removal rate and depth is same. The value gets decreaseswith increase in Wt. % of reinforcement particles.

4.3.3. Variation of pulse OFF (TOFF) (mS) as a function of MRR (g/min), TWR (g/min) and DEPTH (g/min)

The variation of Pulse OFF (mS) as a function of MRR (g/min),TWR (g/min) and Depth (g/min) is shown in Fig. 23, Fig. 24 andFig. 25 respectively. The process parameter Pulse OFF is influencemainly due to the composite in various Wt. % and these outputs are

obtained due to the presence of reinforcement particles such asZrb2 and Tib2. The value given as 4,5,6,7,8 mS during the EDMprocess. The Pulse OFF is the time during which re-ionization of thedielectric take place. An insufficient off time can lead to erraticcycling and retraction of the advancing servo thereby slowingdown the operation cycle [27]. In all the three parameters, the valueof MRR, TWR and Depth are maximum in 0% of reinforcement and

it reduces gradually and posse's minimum value in the highest Wt.% of reinforcement with matrix alloys Al 4032. The variation ofPulse OFF with depth shows a lighter deviation that the Wt. %(4,6,8) of composite alloy posses same value of depth (g/min).

5. Conclusion

1. The mechanical test is successfully carried out to calculate thetensile strength, compressive strength and hardness for five setsof specimen with various Wt. % of reinforcement particles withmatrix alloy Al 4032. This test has been conducted as per theASTM standards. The value of the mechanical property of the Al4032 composite alloy is considerably increased along with theincrease in Wt. % of various reinforcement particles such as Zrb2and Tib2 when compared with unreinforced Al 4032 alloy. Theimprovement in ultimate tensile strength of developed com-posites is attributed to the fine size and cubical shape of Tib2

Fig. 18. Variation of current (amps) with TWR (g/min).

Fig. 19. Variation of current (amps) with Depth (g/min).

Fig. 20. Variation of pulse on (mS) with MRR (g/min).

N.V. Rengasamy et al. / Journal of Alloys and Compounds 662 (2016) 325e338336

particles formed in situ. The ultimate compressive strength ishigh due to the reinforcement particles act as a second phase

and resist the movement of dislocation in the matrix composite.The significant level of bonding between the matrix materialand reinforcement is the foremost factor in deciding theenhancement of hardness value of composite materials.

2. The Taguchi L25 orthogonal array is used to identify the mostinfluencing process parameter in obtaining minimum materialremoval rate, tool wear rate, and depth are obtained value about0.190 (g/min), 0.005 (g/min) and 2.155 (g/min) from the inputparameter value of about 8 W t. % composites, Pulse ON (TON)Pulse OFF (TOFF), Current of about 7.0 (mS), 7 (mS), 26 (Amps)respectively.

3. The ANOVA method is used to calculate the percentage ofcontribution of each process parameter in influencing the ma-terial removal rate is composites (81.53%) followed by Pulse ON(8.72%) and Pulse OFF (4.26%). Tool wear rate is influenced byprocess parameter in percentage of contribution is compositesof (80.46%) and next is Pulse ON (8.59%) and Pulse OFF (2.34%).The depth of cut is influenced by the process parameter inpercentage of contribution is composites of about (94.95%),Pulse ON (3.76%) and Pulse OFF (0.50%).

4. The variation of current (amps), Pulse ON, Pulse OFF of the Al4032 composite alloy is measured as a function of MRR (g/min),TWR (g/min) and DEPTH (g/min). it proves that, the increase inreinforcement particles such as Zrb2 and Tib2 with matrix alloy

Fig. 21. Variation of pulse on (mS) with TWR (g/min).

Fig. 22. Variation of pulse on (mS) with Depth (g/min).

Fig. 23. Variation of pulse OFF (mS) with MRR (g/min).Fig. 24. Variation of pulse OFF (mS) with TWR (g/min).

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Fig. 25. Variation of pulse OFF (mS) with Depth (g/min).

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enhances the hardness property and strength where the MRR,TWR and depth are minimum and affecting removal rate.

Acknowledgment

The authors like to express our sincere thanks to Research &Development centre for providing us ambient laboratory facilitiesat RVS Educational Trust's Group of Institutions, RVS School ofEngineering & Technology, Dindigul, Tamilnadu.

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