Modeling of material removal morphology and prediction of surface roughness based on WEDM successive discharges

Abstract

In this paper, a successive discharge material removal model is proposed to predict the surface roughness of the EN-GJL-250 (gray cast iron) under different discharge parameters of wire-cut electrical discharge machining (WEDM). Firstly, the finite element method (FEM) was used to analogue simulate the distribution of material surface temperature and flow field in the WEDM single pulse discharge machining process. According to the principle of energy conservation, the surface morphology and characteristic parameter size of a single pulse crater under different discharge parameters are simulated. Secondly, the discharge position is determined by the minimum gap width between the initial surface of the workpiece and the electrode wire during the establishment of the material removal model. Simulation results show that the magnitude of the single pulse discharge energy has an important influence on the morphology and characteristic size of the crater. Due to the different discharge energy, the increasing trend of crater radius, depth, and flanging height is not synchronized, and the increase of crater radius is more obvious and rapid. Meanwhile, the final morphology of the WEDM machined surface is determined by the morphology size of a single pulse crater and the location distribution of discharge points. Finally, the same discharge parameters are used to verify the surface quality of machined materials. Experimental results show that the surface morphology of the WEDM workpiece is in good agreement with the material removal model and the average relative error of surface roughness between the simulation results and the experimental results is 8.26%.