Discharge crater formation simulation coupled by thermo-fluid analysis of arc plasma in EDM

Electrical discharge machining (EDM) is a thermal process. Thermal energy generated by a pulse discharge between the tool electrode and workpiece results in melting and evaporation followed by material removal of both the tool electrode and workpiece, forming a discharge crater on electrode surfaces. In order to clarify the crater formation process in EDM a novel simulation method was proposed in this study. As the heat source of EDM, the arc plasma directly affects the heating state of the discharge spot, which is the most direct factor affecting the material removal. Therefore, in this study, the heat flux and the pressure distribution of the arc plasma were calculated firstly by thermo-fluid analysis. Then the simulation of discharge crater formation were realized by coupling the thermo-fluid analysis results of arc plasma and based on the thermo-hydraulic coupling model for the discharge crater. With this model not only the thermal phase transition of material caused by the high temperature is considered, the hydrodynamic characteristics of molten pool is also included. With this simulation method, the influences of discharge parameters, such as the discharge current, the gap distance and the discharge duration, on the discharge crater were investigated.