Machining of EN19 steel using cryogenically cooled electrode material in electric discharge machining

Abstract

The machining of high-strength alloys like EN19 steel poses significant challenges due to their inherent hardness and susceptibility to surface defects during conventional machining processes. In this study, we explore a pragmatic approach to address these challenges by investigating the implementation of cryogenically cooled electrode materials in electric discharge machining (EDM) for EN19 steel. Specifically, cryogenic treatment is applied to copper electrodes with varying soaking durations of 12 and 24 h. The research considers input process parameters, including peak current ( IP), pulse on time ( Ton), flushing pressure, and soaking duration. Material removal rates (MRR), electrode wear rate (EWR), and surface roughness (SR) are considered as the response parameters. To optimize these input parameters, the study employs the VIKOR technique. Improving the in-depth analysis, our investigation incorporates using COMSOL Multiphysics simulation to intricately model the mechanical aspects of single-spark EDM, mainly focusing on the thermal and structural characteristics of both electrodes and the workpiece. The simulation lends strong support to the experimental findings in relation to MRR and EWR. The experimental data demonstrates notable enhancements after a 24 h cryogenic soaking period for copper electrodes. Specifically, we observed a remarkable 77.36% increase in electrical conductivity, a substantial 20% augmentation in MRR, a significant 39% reduction in EWR, and a noteworthy 9.8% decrease in SR. The meticulous synergy of experimental exploration, optimization, and simulation offers a transformative outlook toward augmenting machining efficacy and prolonging electrode longevity, particularly in the context of EDM.