Multi-Objective Particle Swarm Optimization of WEDM Process Parameters for Inconel 825

Abstract

With the increased diversity of the customer demand and complexity of the product Inconel 825 is widely used to meet the actual needs especially in aerospace industry. It is difficult-to-cut material because of its high toughness and hardness. The present research attempts to optimize the process parameters of wire electric discharge machining (WEDM) during cutting operation of Inconel 825. WEDM characteristics such as pulse-on time (Ton), pulse-off time (Toff), spark gap voltage (SV), peak current (IP),wire tension (WT), wire feed (WF) are taken into consideration. Performance was measured in terms of material removal rate (MRR), surface roughness (SR) and wire wear ratio (WWR). Central composite design (CCD) of response surface methodology (RSM) at α value of ± 2 was employed to establish the mathematical model between process parameters and performance measures. Multi-objective particle swarm optimization (MOPSO) algorithm has been used to find the Pareto optimal solutions. It uses the concept of dominance to find the non dominated set in the entire population and crowding distance approach to find best Pareto optimal solutions with a good diversity of objectives. The confirmation experiments of MOPSO algorithm shows the significant improvement in MRR (27.934 to 31.687 mm2/min), SR (2.689 to 2.448μm) and WWR (0.027 to 0.030). SEM micrograph studies showed the number of cracks, pockmarks, craters, and pulled out material on the workpiece and wire electrode surface. Energy Dispersive X-ray analysis is performed to investigate the presence of elements on the work surface other than base material.