The role of electrical parameters in adding powder influences the surface properties of SKD61 steel in EDM process

Abstract

The surface properties during the electrical discharge machining (EDM) with various powders have been studied. However, the tungsten carbide powder has received little attention from researchers due to its high melting point. Hence, in this study, the surface properties (the surface roughness, Ra, and the micro-hardness of the surface, HV) of the workpiece SKD61 were investigated in the EDM process with tungsten carbide powder mixing (PMEDM) at the fine finishing and semi-finishing of electrical parameters. Through evaluation and analysis, it is found that the influence of powder is positive to improving surface properties at the small peak current and the short pulse time on. Moreover, the surface characteristics between the EDM and PMEDM method have been compared and assessed comprehensively on a wide range of technological parameters, that is given an overview of the effect of the powder on changing the surface characteristics; the surface roughness and the micro-hardness of the surface obtained by PMEDM are generally better than those obtained by normal EDM. The best improvement in surface roughness and micro-hardness of the PMEDM method is 53.25% and 81.5%, respectively, at Ip = 2A; Ton = 16 µs; Cp = 60 g/l as compared to the EDM method. In the study, it also clarified the mechanism of PMEDM with the participation of powder particles. The method can be applied for improving surface quality such as improving the strengthening of hot stamping mold and machine parts working at high temperatures.