Simulation research on the thermal phase transition of EDM and the formation mechanism of remelted layer in single pulse spark discharge crater

Abstract

The remelted layer formed by the Electrical Discharge Machine(EDM)impacts surface quality of small hole and significantly reduces the fatigue life of workpieces. Based on Comsol Multiphysics ,this paperusessimulates the formation process of the remelted layer under single-pulse condition. When horizontal set and two-phase flow methods are used to track the phase interface, the model is built under the coupling of flow and heat transfer fields, which simulates the solid-liquid-gas transformation during discharge etching via porous medium and weak expression methods. The simulation results show that the temperature rapidly decreases from the midpoint of the discharge center axis to the surrounding area, and the radius of the plasma region is 95.3 µm. The diameter of the pit is 108.5 µm. The thickness of the remelted layer is 16 µm. The thickness of the remelted layer obtained from experiments under the same conditions is 16.4um. The comparison shows that the difference between the two is small, indicating that the simulation model can accurately predict the thickness of the remelted layer, providing a new approach for evaluating the thickness of the remelted layer in EDM.