Development of a comprehensive sustainability index for micro-EDM in blind micro hole fabrication using multi-criteria decision analysis

Blind micro-hole fabrication by micro-electrical discharge machining (micro-EDM) is limited by one-directional flushing: debris cannot leave the far side of the workpiece and recirculates through the gap, penalising surface integrity, dimensional accuracy and energy efficiency simultaneously. Existing studies treat these penalties as independent objectives and offer no scalar metric for parameter selection. This paper develops a Composite Sustainability Index (CSI) that fuses nine technical, economic, environmental and social indicators into a dimension-free score bounded by 0 and 1. Weights are derived by the Analytic Hierarchy Process from a seven-member expert panel (consistency ratio 0.019) and runs are ranked by TOPSIS. Validation uses a Taguchi L9 experiment on Ti-6Al-4 V with a 100 µm copper electrode and three dielectrics: distilled water, EDM oil and a 50:50 (v/v) mixture. The best condition (pulse-on time 2 µs, peak current 1.0 A, mixed dielectric) reaches a CSI of 0.637. Technical criteria carry 47.1% of the weight and surface roughness alone explains 38.4% of the inter-run CSI variance, while analysis of variance attributes 43.9% of that variance to dielectric choice. Cross-validation against GRA, VIKOR and MOORA and ±15% weight perturbations (Spearman ρ > 0.88) confirm rank stability. The framework is materials-agnostic and needs no extra instrumentation.