Multi-Objective Optimization of Electrochemical Discharge Machining (ECDM) of Inconel 625 for Aerospace Applications

Abstract

The present study focuses on the multi-objective optimization of electrochemical discharge machining (ECDM) of Inconel 625 using a Taguchi-based Entropy-TOPSIS approach. Unlike conventional studies primarily considering MRR and surface roughness (Ra), this investigation additionally incorporates overcut, form error, and orientation tolerance error to comprehensively evaluate machining performance. The optimal parameter combination was identified as feed rate (F) of 0.20 mm/min, flow rate (Q) of 0.75 L/min, and electrolyte concentration (C) of 10%. Taguchi analysis revealed non-monotonic effects of F and Q, while C exhibited a decreasing trend in the closeness coefficient (Ci⁺). ANOVA identified F, Q, and their interaction (FxQ) as the most influential factors, whereas C was individually insignificant but showed a meaningful interaction with Q. The regression model demonstrated good predictive capability with R² = 94.23% and adjusted R² = 91.18%. Overall, the Taguchi-Entropy-TOPSIS methodology proved effective for optimizing multiple machining responses and improving the overall ECDM performance of Inconel 625.