Experimental Investigation and Analysis of EDM Characteristics of Inconel 825

Recently, electro-discharge machining (EDM) has become one of the preferred machining techniques for Ni-based super alloys. Although extensive research has been reported on EDM characteristics of Inconel 718, not much information is available on Inconel 825. Owing to the excellent resistance to corrosion, Inconel 825 finds particular application in highly corrosive environment. Therefore, the current investigation aims at studying the influence of different EDM process variable peak current (I ( p )), duty factor (T (au)), and pulse-on duration (T (on)) on various performance characteristics such as material removal rate (MRR), surface roughness (SR), radial overcut (ROC), and surface crack density (SCD). Experiments were designed and carried out using L9 orthogonal array. The most influencing factor for responses MRR, SR, and ROC was found to be I ( p ) with percentage contribution of 51.22%, 81.08%, and 54.78%, respectively, while it was T (on) for SCD with 39.54% contribution. Since EDM involves multiple performance characteristics, a multi-objective optimization technique, i.e., gray relational analysis (GRA) was utilized to optimize process parameters during EDM of Inconel 825. The analysis indicated the optimal combination of process parameters to be I ( p )(1 A), T (on) (10 mu s), and T (au) (75%). The results were further validated using confirmatory experiment.