Optimization of Process Parameters of EDM of Inconel 617 by Taguchi Based PCA and GRA Technique and Effect of Recast Layer Formation

Inconel materials are manufactured in various series which have differences in their chemical composition and hence in its physical and chemical properties. These alloy materials are known for their high strength, corrosion resistance and oxidation resistance. They are not easily machine-able through conventional machining, due to rapid work hardening tendency, high toughness and hardness, tendency to form built up edges, hence for their machining, non conventional machining equipments like EDM are used. A number of experiments has been performed to optimize process parameters of EDM on different series of Inconel material like Inconel 625, Inconel 718, Inconel 601, Inconel hastelloy C-276, Inconel 690 etc. by different optimization technique Taguchi, PCA, GRA etc however there is a lack of data available for optimization of process parameters of EDM machining for Inconel 617. So in this paper optimization of process parameters like Pulse on time, peak current, gap voltage have been done by taking Material Removal Rate and Tool Wear Rate as response variables. Other process parameters have been kept constant during EDM process. It is found that for different values of process parameters pattern of variation of MRR and TWR is different. Also the effect of recast layer formation on MRR and TWR has been analyzed and it is found that at high Peak Current and high Pulse on Time, tendency of formation of recast layer is high. Formation of recast layer adversely affects MRR and TWR i.e. it reduces MRR and TWR. Also Results obtained from PCA and GRA has been compared and it is found that both methods give same optimum set of process parameters but they have differences in pattern of variation of MRR and TWR.