Multi-objective Optimization of Inconel 718 Using Combined Approach of Taguchi—Grey Relational Analysis

Nickel-based alloy such as Inconel 718 is widely used in aerospace, automobiles, gas turbines, nuclear and chemical industries. Inconel 718 is a high-strength temperature resistance which exhibits good resistance to corrosion. In the current paper, Taguchi’s L9 orthogonal array is implemented for wire electrical discharge machining (WEDM) with three factors at three levels. The influence of input variables such as pulse-on time, current and pulse-off time has been investigated on the material removal rate and surface finish. ANOVA analysis has been carried out to check the significance of variables and their effect on output variables. For MRR, all three input parameters are found to be significant pulse-on time and the current is found to have an influence on SR. As Taguchi’s technique can optimize only one objective at a time with no consideration of its effect on another output parameter which may result in either lower production or pitiable quality. To satisfy such conflicting objectives at the same time, an optimum parameter setting is required. Grey relational analysis was used to get an optimal combination of input variables for multiple output variables. The optimal combination of input parameters is found to be pulse-on time 55 µs, pulse-off time 5 µs and current 2 A. Predicted values obtained at an optimal condition using GRA have been validated by experimental trial and show a very close relationship with negligible error.