Thermal Modeling of EDM with Progression of Massive Random Electrical Discharges

Electrical discharge machining (EDM) is a competitive process to machine difficult-to-cut materials, but thermal damage is a critical concern for the EDMed parts. Finite element modeling provides insight into the thermal damage mechanism in EDM processes. However, current modeling approaches of an EDM process are limited to a single discharge, which is far from reality to predict thermal damage due to the accumulating effect of massive random. In this study, an innovative modeling approach to account for massive random discharges has been developed based on the stochastic EDM process and probability theory. Die sinking EDM of NiTi alloys was simulated to investigate the thermal damage mechanism with the progression of massive random discharges. The temperature history profiles of both top surface and subsurface showed pulsing characteristics with the progression of massive random discharges, which resulted from high-frequency random discharging phenomenon. A large temperature gradient was also found on the area below the top surface, while it gradually decreased in the deep subsurface. The predicted “coral reef” surface topography and uniform temperature distribution across the surface showed that the proposed model accounting for random discharge phenomenon proved to be an effective approach to investigate the effect of EDM processes.