International Journal of Advance Engineering and Research Development

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1 Scietific Joural of Impact Factor(SJIF): 3.34 e-issn(o): p-issn(p): Iteratioal Joural of Advace Egieerig ad Research Developmet Volume 2,Issue 8, August -20 Effect of machiig parameters o MRR ad TWR i EDM of AISI P-20 tool steel usig L 8 orthogoal Array Aruima Sigh, Sharad Srivastava 2, Rohit Sahu 3 P.G. Studet, MED, Rajastha Istitute of Egieerig ad Techology, Jaipur 2 Assitat Professor, MED, Rajastha Istitute of Egieerig ad Techology, Jaipur 3 Assistat Professor, MED, G.L. Bajaj, Greater Noida Abstract Electrical discharge machiig (EDM) is a o-traditioal maufacturig techique that has bee widely used i the productio of precisio egieerig compoets throughout the world i recet years. The most importat performace measure i EDM is the MRR ad TWR. I this study, the experimetal studies were coducted uder varyig pulse o time, curret ad electrode diameter. The umbers of experimets were coducted by L 8 orthogoal array of Taguchi s methodology. Sigal-to-oise (S/N) ratio was employed to determie the most ifluecig levels of parameters that affect the MRR ad TWR i the EDM of AISI P20 tool steel. To validate the study, cofirmatio experimet has bee carried out at optimum set of parameters ad predicted results have bee foud to be i good agreemet with experimetal fidigs. ANOVA fid the ifluece of parameters i the experimets. Keywords- EDM, Taguchi method, MRR, TWR, ANOVA I. INTRODUCTION Electric Discharge Machiig (EDM) techology has Ucovetioal Machiig techique ad become a importat maufacturig process. I today techology there is a heavy demad of the advaced ad difficult to machie materials, such as high stregth thermal resistat alloys or eve some ceramics materials ay hardeed steels. EDM is a thermoelectric process that erosio of material from the work-piece due to series of discrete sparks betwee work piece ad electrode separated by a thi film of dielectric fluid medium []. Electric Discharge Machiig (EDM) is a essetial operatio i several maufacturig i several idustries, which gives importace to variety, precisio ad accuracy. Several researchers have attempted to improve the performace characteristics amely the material removal rate, surface roughess, delimitatio factor, residual stress. But the full potetial utilizatio o f this process is ot completely solved because of its complex ad stochastic ature ad more umber of variables ivolved i this operatio. Kha [2] ivestigated electrode wear ad material removal rate durig EDM of alumiium ad mild steel usig copper ad brass electrodes ad cocluded that electrode wear is more durig machiig alog their cross sectio tha alog its legth. Copper electrode wear less as compare to brass electrode because the thermal coductivity of copper is higher tha brass. Electrode wear is more durig machiig of mild steel tha alumiium. EW is icreases with icreases of curret ad Gap voltage ad MRR is sharply icreases with icreases of curret. Malhotra ad Rai [3] ivestigated the cotrol parameters for surface roughess iside flushig from a die sik EDM ad cocluded that experimetal ivestigatio o the effect of curret, pulse o time, spark Gap, voltage, duty cycle ad flushig pressure o surface roughess wear rate whe usig EDM o EN-3 Die Steel usig copper as electrode, ad fid curret ad pulse o time have maximum ifluece o surface roughess. Cydus [4] developed a model electrode wear (EW) ad recast layer (WLT) through respose surface methodology i a die sikig EDM process. For this purpose a c etral composite rotatable desig (CCRD) ivolvig three variables with five levels employed to establish a mathematical model betwee iput parameters ad resposes (EW & W LT) ad coclude that Pulse curret was foud the most importat factor effectig the both EW ad WLT, while pulse off-time has o sigificat effect o both resposes. Bhattacharya et al [] performed a experimet to see the Performace of ZrB2 Cu composite as a EDM electrode as the low wear resistace of electrodes like Cu, Cu alloys ad graphite is a major problem for electrical discharge machiig (EDM) operatio. I this research they made a attempt to develop a metal matrix composite (ZrB2 Cu) to get a optimum combiatio of wear resistace, electrical ad thermal coductivity. For differet process parameters of EDM durig machiig of mild steel. The ZrB2 40 wt% Cu composite showed more metal removal rate (MRR) with less tool wear rate (TWR) tha commoly used Cu tool. But the diametric overcut ad average surface roughess are foud to be lesseig case of Cu tool tha composite tool. Bao et al. [6] Material removal ad surface damage of Ti3SiC2 ceramic durig electrical discharge machiig (EDM) were ivestigated. As icreasig i the discharge curret, workig voltage, but i creased declaratively with pulse duratio. Micro cracks i the surface ad loose grais i the subsurface resulted from thermal shock were cofirmed, ad the surface damage i Ti3SiC2 ceramic led to a degradatio of both stregth ad reliability.. Kiyak et al. [7 ]the experimetal study of the EDM of 40CrMNiMo864 tool steel (AISI P20) tool steel they Examie machiig parameters o surface roughess i EDM of tool steel George et al [8] optimize the machiig parameters i the EDM machiig of C C composite usig Taguchi method. The process variables affects electrode wear rate ad MRR, accordig to their relative sigificace, are Vg, Ip ad To, All rights Reserved 42

2 Iteratioal Joural of Advace Egieerig ad Research Developmet (IJAERD) I the past, maufacturers have tried to eumerate the cotrol parameters to improve machiig qua lity. Literature review idicates that a umber of iput parameters affect the quality of machied compoet i die sik EDM. I this study, the effect of machiig parameters ad their levels of sigificace o the material removal rate ad electrode wear were statistically evaluated by usig aalysis of variace (ANOVA). Experimets were coducted uder differet machiig parameters amely, pulse o time, electrode diameter ad discharge curret. The settigs of machiig parameters were determied usig Taguchi Method. II. EXPERIMENTAL WORK The experimets were performed o a ELECTRONICA- ELECTRA PLUS PS 0 ZNC EDM machie tool. The compositio of AISI P-20 tool steel work material used for experimetatio i this work is a give i Table. U shaped Copper electrode with 4 ad 6 mm diameter was used i the experimets. The parameters, selected for various settigs of pulse o time, electrode diameter ad discharge curret were used i the experimets Table 2. The photo graphic view of the machiig zoe has bee show i figure. Table Compositio of AISI P-20 steel Elemets C Si M Cu Cr Mo P S Weights % Taguchi Method Taguchi method has become a power full tool for improvig productivity durig research ad developmet so that high quality products ca be produced quickly ad at low cost. This is i cotrast to the traditioal method for cotrollig the source of the variatio (variatio of evirometal coditios ad other oise factors) at low cost [9]. Figure Experimetal setup Figure 2 Machied work-piece To evaluate the effects of machiig parameters of EDM process i terms of machiig Performace characteristics such as MRR ad EW a Taguchi method used here to model the EDM process. I this study, Taguchi method, a powerful tool for parameter desig of performace characteristics, for the purpose of desigig ad improvig the product quality. I the Taguchi method, process parameters which ifluece the products are separated ito two mai groups: cotrol factors ad oise factors. The cotrol factors are used to select the best coditios for stability i desig or maufacturig process, whereas the oise factors deote all factors that cause variatio. Accordig to Taguchi based techique, the characteristic that the smaller value idicates the better machiig performace, such as MRR is addressed larger-the-better ad EW is addressed as smaller-the-better type of problem. The S/N Ratio, i.e. η, ca be calculated as show below: 2 y S/N ratio = η = 0log () i All rights Reserved 43

3 Iteratioal Joural of Advace Egieerig ad Research Developmet (IJAERD) 2 S/N ratio = η = 0log (2) The process parameters chose for experimets are: pulse o time (T o ), peak curret (I p ) ad electrode diameter (D) while the respose fuctio are MRR ad EW. Accordig to the capability of commercial EDM machie available ad geeral recommedatios of machiig coditios for AISI P-20 tool steel the rage ad the umbers of levels of the parameters are selected as give Table 2. i y EWR Table 2 Settig of levels for process parameters Parameters Uit Symbol Level I II III Electrode Diameter mm D Pulse o time µs T o Discharge curret A Ip 3 Table 3 Experimetal desig usig L 8 orthogoal array Ru Dia (mm) Ip (A) To (μs) MRR (g/mi) S/N ratio (db) TWR (g/mi) S/N ratio (db) III. RES ULT AND DISCUSSION This phase of the desig of experimet process is to aalyze ad iterpret the experime tal results to improve the performace characteristics of the EDM process. This approach is used i a simplified way to subjectively poit out colum which has large ifluece o the respose. The some data associated with first level, secod level ad third level is oted that ad differece of largest ad smallest of the three levels represets delta. The magitudes of differeces are compared to each other, to fid out the relatively strog cotrol factors. Table 4 ad show the result of this method. Accordig this method, the priority level of sigificat parameters, for performace characteristic MRR ad TWR are as follows: Ip, To ad D ad Ip, To ad D respectively. Table 4 S/N ratio respose table for MRR Level Diameter Curret Pulse o time Delta Rak 3 2 The mai effect plot for MRR ad EW show Figure 3 ad Figure 4. Aalysis of the result, leads the coclusio the factors at level Electrode Diameter (Level 2), Ip (Level 3) ad To (Level 3) gives the maximum MRR. Similarly, All rights Reserved 44

4 Mea of SN ratios Iteratioal Joural of Advace Egieerig ad Research Developmet (IJAERD) recommeded from figure, use the factors at level Electrode Diameter (Level ), Ip (Level 3) ad To (Level 2) for miimizatio of Tool wear rate.. Table S/N ratio respose table for EW Level Diameter Curret Pulse o time Delta Rak 3 2 By statistically there is a evaluatio tool these are provides a results at some cofidece lev el as to whether results estimates are sigificatly differet. A better feel for the relative effect of the differet machiig parameters o the MRR ad EW was obtaied by decompositio of variaces, which is called aalysis of variace [0]. The results of ANOVA for the machiig outputs are preseted i Tables 6 ad Table 7. Larger F-value idicates that the variatio of the process parameter makes a big chage o the performace characteristics. For this experimetal study cofidece level equals 9% ad α risk equal to 0.0 is chose. Table 6 Aalysis of Variace for Mea data for MRR Parameters DF SS Adj SS V F-ratio P D Ip To D Ip D To Ip To Residual Error Total Table 7 Aalysis of Variace for Mea data for EW Parameters DF SS Adj SS V F-ratio P D Ip To D Ip D To Ip To Residual Error Total For the MRR ad EW the F-ratios from the tabulated value are as follows: F 0.0; 4; 7 = Accordig to the above statemet, parameters To, Ip are sigificat factors ad D are isigificat factors ad factors Ip are sigificat factor. To ad D are isigificat factors remaiig factors (colums) are estimates of error variace respectively. Mai Effects Plot for SN ratios Data Meas DIA IP TON Sigal-to-oise: Larger is better Figure 3 Mai effect plot of All rights Reserved 4

5 Mea of SN ratios Iteratioal Joural of Advace Egieerig ad Research Developmet (IJAERD) Mai Effects Plot for SN ratios Data Meas 9 DIA IP TON Sigal-to-oise: Smaller is better Figure 4 Mai effect plot of EW IV. CONFIRMATION EXPERIMENTS The last stage experimets after selectig optimal parameters by the Taguchi s methodis to be predict to verifyig improvemet of machiig performace characteristics ad fidig the optimal machiig parameters [9]. The predicted S/N ratio usig the optimal levels of the machiig parameters ca be calculated with the help of followig predictio equatio: Here, η opt is the predicted optimal S/N ratio, η m is the total mea of the S/N ratios, η j is the mea S/N ratio of at optimal levels ad k is the umber of mai desig parameters that affect the quality characteristics. Table 6 Results of cofirmatio experimets for MRR ad EW Respose Parameters D (mm) I p (A) T o (µs) Predicted Value Experimetal Value MRR Level values EW Level values 4 00 V. CONCLUS ION The effect of die sikig EDM process parameters i terms of Material removal rate ad electrode wear rate of AISI P-20 tool steel usig Taguchi s L 8 orthogoal array. It is observed that the S/N Ratio with Taguchi s parameters desig is a simple, systematic, reliable ad more efficiet tool for optimizig performace characteristics of Die sikig EDM process parameters. Based o the experimetal results ad aalysis, the followig coclusios ca be draw: For maximum material removal rate ad miimum electrode wear optimal combi atio of process parameters are electrode diameter (6mm), discharge curret (A), pulse o time (000μs) ad electrode diameter (4mm), discharge curret (A), pulse o time (00μs) respectively. Discharge curret ad pulse o time were foud to be the sigificat parameters. Icreasig pulse o time ad discharge curret leads to high productivity of mach iig respose as material removal rate. Pulse o time is sigificat parameter leads to low quality of the electrode wear. Actual gai 2.86 for MRR is very close to the predicted It shows very good reproducibility ad cofirms the success of the All rights Reserved 46

6 Iteratioal Joural of Advace Egieerig ad Research Developmet (IJAERD) REFERENCES [] K. H. HO, S. T. Newma, State of the art of Electrical discharge machiig (EDM), It. J. of Machie Tools ad Maufacture, vol. 43, pp , [2] A.A. Kha, Electrode wear ad material removal rate durig EDM of alumiium ad mild steel usig copper ad brass electrodes, Iteratioal Joural Advace Maufacturig Techology, vol. 39, pp , October [3] Navdeep Malhotra, Soa Rai ad Khalid sheikh, Optimizatio of cotrol parameters for surface roughess i sid e flushig form of die sik EDM, Joural of egieerig research ad studies, pp , 20. [4] Ulyas Caydas, Ahmet Hascalik, Modelig ad aalysis of electrode wear ad white layer thickess i die -sikig EDM process through respose surface methodology It. J. Adv. Mauf. Techol, vol. 38, pp. 48-6, [] A.K. Khara, B.R. Sarkar, B. Bhattacharya, L.C. Pathak ad M.M. Godkhidi, Performace of ZrB2 Cu composite as a EDM electrode, Joural of Materials Processig Techology, vol. 83, pp , [6] C.F. Hu, Y.C. Zhou ad Y.W. Bao, Material removal ad surface damage i EDM of Ti3Si C2 ceramic, Ceramics Iteratioal, Vol. 34, pp. 37-4, [7] M. Kiyak, O. Cakir, Examiatio of machiig parameters o surface roughess i EDM of tool steel, Joural of Materials Processig Techology, vol. 9, pp. 4 44, [8] P.M. George, B. K. Raghuath, L.M. Maocha ad Ashish M. Warrier, EDM machiig of carbo -carbo composite a Taguchi approach, Joural of material processig techology, vol. 4, pp. 66-7, [9] Rajit K. Roy, Desig of experimets usig the Taguchi approach: 6 steps to product ad process improvemet, Joh Wiley & Sos, Ic. New York, 200. [0] D. C. Motgomery, Desig ad aalysis of experimets, Wiley, New York, All rights Reserved 47