Die-sinking EDM performance under the effect of tool designs and tool materials

In the dies and molds making sector of manufacturing engineering there is a prominent use of die-sinking electric discharge machining (EDM). Several studies are being carried out addressing the potential of EDM and its associated challenges. In addition to understanding the complex machining phenomenon of EDM, bringing improvements in its material removal rate, machining time, tool wear, and geometrical accuracy of the machined feature are the visible interests of research community. In this context, the present study has been carried out to improve EDM performance measures named as machining time (MT), relative electrode wear (REW), diametric overcut (DOC), hole taper angle, and surface roughness (Ra). Through-holes of circular profiles are machined in D2 steel (a widely used material of dies and molds). Conventional tool design (D_C) is modified with the provision of relief angles named as non-conventional designs (D_RA) and the effect of tool designs on said responses are studied. D_RA designs are employed on three different electrode materials, i.e. pure copper (Cu), copper-tungsten (CuW), and graphite (Gr) to examine the combined effect of tool designs and materials. In comparison with the conventionally used electrode design (D_C), the non-conventional designs (D_RA) of Cu, CuW, and Gr have shown significant improvements in MT, REW, DOC, hole taper, and surface roughness with a percentage reduction of 47.28%, 91.29%, 37.35%, 9.4%, and 38.68%, respectively. Among tool designs and tool materials CuW tool having 10 deg relief angle has been found as the appropriate tool resulting in the optimized values of response measures.