Hybrid optimization of WEDM control parameters for Kovar using VIKOR-AHP and R method

Kovar alloy is widely used in electronics, aerospace, and precision applications due to its thermal expansion compatibility with ceramics and glass, yet its difficult machinability demands optimized WEDM parameters for improved performance. To address this challenge, the present study aims to evaluate the influence of key WEDM factors and identify optimal machining conditions for Kovar. Experiments were conducted using a Taguchi L₂₇ orthogonal array considering servo voltage, pulse on-time, pulse off-time, and wire feed rate as machining parameters, and their effects on cutting speed, machining time, and surface roughness were systematically analyzed. A hybrid multi-criteria decision making approach combining AHP-based weighting with VIKOR compromise ranking was employed alongside the R-method for comparative validation. Results show that the parameter set Ton: 121 µs, Toff: 49 µs, SV: 20 V, and WF: 4 m/min. achieved the best overall machining performance. Importantly, both the AHP-VIKOR method and the R-method identified the same optimal settings, demonstrating strong agreement and confirming the robustness of the hybrid optimization framework. The study highlights the scientific contribution of integrating statistical ranking with structured multi-criteria analysis to enhance decision quality in multi-response WEDM optimization for Kovar alloy.