Improving the performance of EDM through relief-angled tool designs

Abstract

Among the family of carbides, tungsten carbide (WC) and its variants have extensive use in numerous applications including cutting tools, dies, and many wear resistant parts. Such applications need machining of WC, which is famously considered as challenging due to high tool wear mainly in traditional machining. Sinking electric discharge machining (EDM) can be considered as a suitable alternate but the low machining rate of EDM, with conventional tool design, poses limitations. In this research, the conventional tool design is modified by providing relief angles to the tool electrodes. The relief-angled tool electrodes are first time introduced in this research to machine through holes. The role of the relief angle during EDM has been investigated in terms of six response characteristics, i.e., machining time, hole taper angle, radial overcut at the hole entrance, radial undercut at the hole exit, longitudinal tool wear, and roughness of inside hole surfaces. The performance of the relief-angled electrodes is found to be significantly better than the performance of conventional cylindrical tool. In addition to improvements in other responses, a 49% reduction in the machining time has been realized by the use of relief-angled electrode indicating a worthwhile contribution in the field of electric discharge machining.