Thermal model of crater formation process in electrical discharge machining

The formation mechanism of the discharge crater in electrical discharge machining process is not fully understood, which affects the application of electrical discharge machining technology. In this paper, a thermal-fluid coupling model was proposed by COMSOL Multiphysics software, and the influence of discharge parameters, including peak current, pulse on-time, and the material of tool electrode and workpiece, on crater formation process was analyzed. The temperature distribution, the flow field velocity, heating region, and morphological changes of the discharge crater were analyzed to illustrate the formation mechanism of the discharge crater. By comparing the experimental results with the numerical simulation results, it was found that under the same discharge energy, the peak current has a greater influence on the discharge crater size than the pulse on-time. Moreover, through analysis of the influence of tool electrode materials and workpiece materials, it was found that the crater size is influenced by the boiling point of tool electrode material and the melting point of workpiece material. The experimental and numerical simulation results showed that the simulation results are consistent with the experimental results, which verifies the applicability of the thermal-fluid coupling model in studying the crater formation mechanism in electrical discharge machining.