Optimization of WEDM parameters for Mg-Zn-RE-Zr alloy using Passing Vehicle Search algorithm

Abstract

Wire Electric Discharge Machining (WEDM) is a high precision spark machining capable of cutting electrically conductive materials of varying hardness and/or having complex shapes. Since the last decade, focus has increased on magnesium alloys because of their high specific strength and inelasticity, excellent damping properties. The addition of Rare Earth (RE) improves creep and corrosion resistant properties thus rendering them highly useful for several aerospace applications. In the present study, parametric optimization of WEDM on Mg-Zn-RE-Zr alloy is performed using a novel meta-heuristic algorithm-Passing Vehicle Search (PVS). The control parameters considered are current, pulse-on time, pulse-off time and wire feed rate. Response Surface Methodology (RSM) philosophy is implemented through Central Composite Design (CCD) to formulate the mathematical model of Average Surface Roughness (Ra). The adequacy of obtained quadratic model is established using Analysis of Variance (ANOVA). The PVS algorithm employs a population based search method by emulating the algebraic characteristics of vehicles over-taking on a two-lane highway from an initial solution set. Results of optimization through PVS are compared against standard real coded Genetic Algorithm. A remarkable improvement was observed which is critical while considering aerospace standards. This kind of analysis could be useful for production process planning in the aerospace industry.