SURFACE TOPOGRAPHY AND OPTIMAL MACHINING CHARACTERISTICS INVESTIGATION FOR ADVANCED ENGINEERING MATERIAL INCONEL 825 ALLOY EXPLORING STATISTICAL TGRA ACCOMPANIED WITH T-TOPSIS METHODOLOGY

Abstract

The electrical discharge machining (EDM) is an extremely effective manufacturing process to create deep and three-dimensional complex cavities. In EDM, machining occurs due to the generation of thermoelectric energy between the work piece and an electrode. EDM widely engaged for cutting superalloy material that are having high strength to wear ratio, corrosion resistance, etc. In this work, Inconel 825 material, which is nickel–chromium based superalloy, is opted due to its outstanding mechanical and thermal properties. We considered various important EDM input parameters, i.e. spark gap (Sg), gap voltage (Vg), pulse on time ([Formula: see text]), pulse off time ([Formula: see text]), peak current ([Formula: see text]), servo feed (Sf), depth of cut (Dc) and difficulty index (Di) with Taguchi L[Formula: see text] orthogonal array for optimizing output responses, i.e. tool wear rate (TWR), material removal rate (MRR) and surface crack density (SCD) in multi-objective optimization (MOO) realm. Undertaking repeated experimental runs are very expensive, tedious, time consuming and economically unjustified. Hence, we have robustly introduced a novel integrated computational Taguchi based grey relational analysis (TGRA) accompanied with Taguchi based technique for order of preference by similarity to ideal solution (T-TOPSIS) to optimize the EDM process. This research represents that the pulse on time is the chief significant factor and the [Formula: see text] value is found as 0.002 for both TGRA and T-TOPSIS. Experimentally, it has been confirmed that the optimum settings yielding an improvement of 0.01627 and 0.28071 in TGRA and T-TOPSIS score, respectively. The comparative analysis for the methodologies is fruitfully discussed and the results clearly present the effective parametric combinations to be implicated for optimizing MOO framework. Investigation of surface topography is fruitfully presented and the effects of the pulse on time, gap voltage and pulse off time on heat affected layers, machining debris and surface cracks were also discussed. Validation tests were carried out and show closer relationship with the experimental results.