Multi-Parametric Optimization of Electrical Discharge Machining of Inconel-690 Using RSM-GRA Technique

In many industries, alloys of nickel have extensive range of applications for their noteworthy properties like corrosion resistance, high temperature tolerance and resistance to creep rupture. Nickel-chromium (Ni 690) alloys being precipitation hardenable are broadly employed in aircraft structures, gas turbines, rocket engine thrust chambers, pressure vessels and nuclear reactors. Machining of Inconel 690 is very hard by traditional routes because of their strong strain hardening nature, poor thermal conductivity and high strengths at very high temperatures. EDM has a thermal process which can be used irrespective of workpiece strength and hardness, to machine Inconel 690 alloy by electrical erosion. In this paper, the investigation of chosen input parameters current (Ip), pulse on time (Ton), gap voltage (V) and pulse off time (Toff) of EDM on Ni-690 alloy on resulting process parameters like surface roughness (SR) and material removal rate (MRR) is considered. Primarily, the experiments were planned and designed with RSM-CCD approach. Grey relational analysis (GRA) was adapted to multi optimize the performance parameters on MRR and SR. In further stages, analysis of variance (ANOVA) approach was selected to reveal the impact of the variables on the performance characteristics of SR and MRR. GRA results show that the EDM performance in the Ni-690 machining process can be improved at confirmation test conditions.