Modelling and optimizing surface roughness and MRR in electropolishing of AISI 4340 low alloy steel in eco-friendly NaCl based electrolyte using RSM

Electropolishing (EP) is a reliable post-processing method of the drilled metals for achieving a high-quality surface finish with an appropriate material removal rate. This process has many applications due to its advantages such as improving the surface quality by removing the surface peaks on a micro-scale. The aim of most attempts on this process is setting up the optimum parameters to obtain maximum Material Removal Rate (MRR) with minimum surface roughness. In the present wo k, electropolishing of AISI 4340 low alloy steel immersed in eco-friendly NaCl solution has been studied numerically and experimentally. So, primarily a simulation model was developed for the EP process on cylinder parts in COMSOL Multiphysics which was validated with experimental approaches. The results revealed that the numerical model would be convenient for EP. The experiments were performed using Response Surface Methodology (RSM) to evaluate the effect of input variables on the responses. The effects of input variables electrolyte temperature, current intensity, and primary gap were investigated on the outputs MRR and surface roughness at five levels. Based on the results, the electrolyte temperature and current intensity were more effective parameters on the outputs. Results of ANOVA and regression analysis approach revealed that by increasing the current and electrolyte temperature, the MRR increases correspondingly and surface roughness declines and the primary gap has a reverse effect on the MRR. Finally, by performing a multi-objective optimization using Derringer’s desirability approach, the EP of AISI 4340 with an eco-friendly NaCl solution was optimized.