Multiphysics thermo-fluid modeling and experimental validation of crater formation and rim development in EDM of inconel C-276

Abstract

Electric Discharge Machining (EDM) is a non-conventional process well-suited for machining hard-to-machine materials, offering high dimensional accuracy and an acceptable surface finish where traditional methods fall short. This study investigates the machining of Hastelloy C-276 using a composite copper-tungsten electrode through a combined experimental approach and a multiphysics thermo-fluid FEM model to simulate crater formation. The model incorporates a Gaussian heat source, energy absorption coefficients, and molten material flow under plasma pressure gradients, considering latent heat, mushy zone viscosity, and temperature-dependent thermophysical properties. Results indicate that optimizing plasma flushing efficiency (∼30 %) at low current and pulse-on time (9 A, 50 µs) enhances material removal while minimizing white layer formation. Higher pulse-on times lead to increased white layer thickness, stabilizing at 25 [A] and 200 [µs]. Surface roughness rises by 33.3 % at 9 [A] and up to 40 % at 25 [A] as pulse duration extends from 50 to 200 µs, highlighting the influence of increased energy input. The model accurately predicts material removal rates and white layer thicknesses, with deviations of 1–5 % from experimental results. These findings provide insights for optimizing EDM parameters to balance material removal efficiency, surface integrity, and process stability.