Experimental investigations into the influence of major operating parameters during micro-electro discharge drilling of cemented carbide

Abstract

Present study investigates the influence of major operating parameters on the performance of micro-EDM drilling of cemented carbide (WC-10wt%Co) and identifies the ideal values for improved performance. The operating parameters studied were electrode polarity, gap voltage, resistance, peak current, pulse duration, pulse interval, duty ratio, electrode rotational speed and EDM speed. The performance of micro-EDM drilling process was evaluated by machining time, material removal rate (MRR), relative electrode wear ratio (RWR), spark gap, surface finish and dimensional accuracy of micro-holes. It has been found that there are two major conflicting issues in the micro-EDM of carbide. If the primary objective is to obtain better surface finish, it can be obtained by the sacrifice of high machining time, low MRR and high RWR. However, for faster micro-EDM, the surface roughness is higher and electrode wear is again much higher. It is concluded that negative electrode polarity, gap voltage of 120V, resistance of 33, peak current of 8A, pulse duration of 21s, pulse interval of 30s, duty cycle of 0.47, electrode rotational speed of 700rpm and EDM speed of 10m/s can be considered as ideal parameters to provide improved performances during the micro-EDM of WC-Co. © 2012 Copyright Taylor and Francis Group, LLC.