PARAMETRIC INVESTIGATION OF POWDER EDM OF METAL MATRIX COMPOSITES

Abstract

In today's scenario increasing the use of metal matrix composites (MMCs) in the area of aerospace, dentistry, automobile, construction etc. Due to the poor machinebility of MMCs has been relatively high cost. In this research work PMEDM process was used to find out the machining characteristics of Al/SiC MMC. In this study graphite (Gr) powder where suspended into dielectric fluid of EDM. The PILOT experiments have been conducted to selection of process parameter and their specified range. The process parameters peak current (Ip), sensitivity, gap control, duty cycle, spark, lift, powder concentration, polarity etc where used to PILOT experiments. Further, response surface methodology (RSM), face center central composite design has been used to investigate material removal rate (MRR), tool wear rate (TWR), surface roughness (SR) and wear ratio of Al/Sic MMC machined by PMEDM. From the PILOT result five process parameters (i.e. peak current (Ip), sensitivity, gap control, duty cycle and powder concentration) have been selected for RSM, face center central composite design. The design provides 50 experiments at different setting of process parameters. The ANOVA of experimental data gives a regression coefficient of second order equations are obtained for different responses. Using this regression equation, the responses surface have been plotted to study the effect of process parameters on MRR, TWR, WR and SR. The experimental results have shown that the MRR in PMEDM is directly proportional to the peak current and inversely proportional to the powder concentration. It was also found that the TWR increases with an increase in current and it gives the lowest value at the 4g/l of powder concentration.