Optimum design of vibratory electrode in micro-EDM process

Abstract

Micro-electro discharge machining (EDM) has a crucial role in fabrication of parts such as molds. One of the most challenging aspects of EDM process relates to flushing of debris. Increasing the material removal rate causes significant enhancement in EDM process. In this study, new numerical approach for enhancing flushing is proposed. A model of vibratory electrode and dielectric flow pattern is validated with theoretical and experimental results. Next, the effect of vibratory electrode geometry and its material properties on flushing of debris is investigated. To this end, design of experiment method is applied to find optimum vibratory electrode shape and material. At first step, vibrational analysis is performed for electrodes to find mode shapes and their corresponding frequency utilizing the finite element method. Vibrational results have good agreement with theoretical ones that are presented in literatures. Next, frequency response function analysis is done for vertical excitation force to find out displacements of electrodes in longitudinal modes. The results of these simulations are utilized to construct 3D computational fluid dynamic (CFD) models to find velocity distribution on gap space between electrode and work piece. Full factorial design is used to evaluate electrode’s parameters. The results from these simulations are studied to achieve best electrode shape that is able to flush the gap flow significantly. Finally, dielectric flow regime for optimum electrode shape is surveyed.