Multiphysics modelling and high-speed imaging-based validation of discharge plasma in micro-EDM

Abstract

Abstract: This paper describes the plasma channel formation during the micro-electrical discharge machining (micro-EDM) at various voltage and capacitance settings. A numerical model using COMSOL Multiphysics finite element is developed to estimate the plasma parameters, such as the plasma channel diameter and temperature distribution in the radial and axial directions. The numerical model also predicts the heat flux distribution responsible for material melting and subsequent removal. Additionally, the coupled numerical model explains the plasma-electrode interactions via different heat transfer mechanisms such as conduction, convection, radiation and thermionic effect. Experimental plasma diameters obtained from high-speed imaging of the discharge process were compared with the simulation results and were in close agreement, with an error between 5% and 14.5%. The simulated molten diameters at various input parameters were compared with experimental crater diameters of single craters and observed to follow a similar trend.