Optimization of Process Parameters to Improve Form and Orientation Tolerances in EDM of MoSi₂-SiC Composites

Abstract

In this research, an investigation and experimental work were carried out on electric discharge machining (EDM) of intermetallic base MoSi2-SiC ceramic composite with copper electrode. It is extremely difficult to machine MoSi2-SiC composite using conventional machining techniques. However, it can be easily machined by executing spark EDM parameters to induce the correct optimum result. These composites find their application in high-temperature environments, viz. fuel turbo pump rotors, inlet nozzles, combustion chambers, injectors, nozzle throats, and nozzle extensions. The sparking parameters, namely current (I), pulse on time (Ton), pulse off time (Toff), spark gap (SG), and dielectric pressure (DP), were investigated by L18 orthogonal array. The optimal process parameters were determined by the grey relational grade (GRG) obtained through the grey relational analysis (GRA) for multiple performance characteristics, viz. material removal rate (MRR), electrode wear rate (EWR), circularity (CIR), cylindricity (CYL), and perpendicularity (PER). The significant process parameters were obtained by analysis of variance (ANOVA) based on GRG, which showed current, pulse on time, and DP. The results were finally established using a confirmatory experiment, which showed the spark eroding process could effectively be improved.