Finite Element Based Modeling of Surface Roughness in Micro Electro-Discharge Machining Process

The development of an accurate model for the prediction of surface roughness is still a key issue for Micro Electro-Discharge Machining (micro-EDM) due to its complex nature. In this paper, a Finite Element Method (FEM) based thermal model is developed to estimate the surface roughness based on the geometry of crater produced during micro-EDM process. The crater geometry is obtained using the temperature field in the workpiece. More real considerations such as Gaussian heat flux distribution, temperature dependent material properties, phase change phenomena and overlapping craters are taken for development of this model. Using the present model, parametric simulations have been carried out to analyze the effect of process parameters such as discharge current, energy partition, breakdown voltage, pulse-on time and duty factor on surface roughness produced on the workpiece. The surface roughness values for AISI 4140 and Ti-6Al-4V workpieces obtained from the present developed model agree reasonably well with the experimental results under the same operating conditions, thus showing the potential usefulness of the proposed approach.