DEVELOPMENT OF HYBRID PROCESS FOR SECONDARY PROCESSING OF METAL MATRIX COMPOSITES

Abstract

Metal matrix composites (MMCs) are advanced materials having the properties of light weight, high specific strength, good wear resistance and a low thermal expansion coefficient. These materials are extensively used in industry. Greater hardness and reinforcement makes them difficult to machine using traditional techniques, which has impeded the development of MMCs. The use of traditional machinery to machine hard composite materials causes serious tool wear due to the abrasive nature of reinforcement. Electrical discharge drilling (EDD) shows higher capability for cutting complex shapes with high precision for these materials. In this study, Al 6063 Hybrid metal matrix composite (HMMC) was drilled by EDD to assess the machinability and obtain an optimal setting of process parameters. The effect of pulse current (AP), pulse-on time (TA), pulse-off time (TB) and tool rotary speed (TS) was investigated on various responses such as material removal rate (MRR), tool wear rate (TWR) and surface roughness during EDD of cast Al 6063-HMMC. The machining conditions were identified for machining performance of the EDD process with respect to material removal rate (MRR). Material removal rate (MRR) and tool wear rate (TWR) were calculated by using mathematical method and the surface roughness was investigated using optical profilometer machine. Statistical software DESIGN-EXPERT v7 was used to establish the design matrix, the regression equations and plots the result and the developed mathematical models were tested. Then analysis-of-variance (ANOVA) method was performed to check their adequacy for the optimization of the process variables. It was found that all the models adopted are of significant level. The experimental results and subsequent analysis revealed that all the selected process parameters were significant.