Modeling of the Anode Crater Formation in Electrical Discharge Machining

Abstract

This research presents a numerical model and the experimental validation of the anode crater formation in electrical discharge machining (EDM) process. The modeling is based on the theory that the material removal process in EDM is composed of two consecutive phases: the plasma heating phase in which intensive thermal energy density is applied locally to melt the work-material and the bubble collapsing phase in which the fluidic impact expels the molten material. A mathematical heat source model with Gaussian distributed heat flux and time variant heating area is applied in the plasma heating phase. Standard modules of a commercial computational fluid dynamics software, fluent, are adapted to model the crater formation in EDM. The material melting is simulated using transient heat transfer analysis and an enthalpy balance method. The volume of fraction (VOF) method is used to tackle the multiphase interactions in the processes of bubble compression and collapsing and molten material splashing and resolidification. Crater and debris geometries are attained from the model simulation and validation experiments are conducted to compare the crater morphology. The simulation and experiment results at different discharge conditions show good agreement on crater diameter suggest that the model is able to describe the mechanism of EDM crater formation.