Influence of process parameters on electric discharge machining of WC/30%Co composites

Tungsten carbide/cobalt (WC/Co) cemented carbide is one of the important composite materials that are used in the manufacture of cutting tools, dies, and other special tools. It has high hardness and excellent resistance to shock and wear, and is not possible to machine easily using conventional techniques. WC/Co cemented carbide produced through powder metallurgy is subjected to electro discharge machining (EDM). In this study four design factors: electrode rotation (S), pulse on time (T), current (A), and flushing pressure (P) of EDM, were chosen as variables in order to study the process performance in terms of material removal rate (MRR) and surface roughness (R-a). The experiments were performed on a newly designed experimental set-up developed in the laboratory. The response surface methodology is used to identify the most influential parameters for maximizing metal removal rate and for minimizing the surface roughness. The recommended optimal process conditions have been verified by conducting confirmation experiments. The experimental results are used to develop the statistical models based on the second-order polynomial equations for the different process characteristics.