Modeling of Melt-Pool Formation and Material Removal in Micro Electro-Discharge Machining

Abstract

This paper presents a μ – EDM melt-pool model to predict workpiece (anode) material removal from a single discharge μ – EDM process. To model the melt-pool heat transfer and fluid flow equations are solved in the domain containing dielectric and workpiece material. A level set method is used to identify solid and liquid fractions of the workpiece material when the material is molten by μ – EDM plasma heat flux. The plasma heat flux, plasma pressure and the radius of the plasma bubble have been estimated by a μ – EDM plasma model and serve as inputs to the melt-pool model to predict the volume of material removed from the surface of the workpiece. Experiments are carried out to study the effect of inter-electrode voltage and gap distance on the crater size. For inter-electrode voltage in the range of 100–150 V and gap distance of 0.5–2 μm, the model predicts crater diameter in the range of 150–165 μm and maximum crater depth of 25–35 μm for discharge duration of 5 μs. The crater sizes for most of experimental craters at higher gap distances show good agreement with the simulated crater shapes. However, at lower gaps, the model over-predicts the crater size.