Multi Objective Optimization of Wire EDM Machining Parameters for AA7075-PAC Composite Using Grey - Fuzzy Technique

Abstract

Wire cut discharge Machining is an advanced machining method controlled by a variety of interrelated complex parameters like discharge current, pulse on time, pulse off time and servo speed rate. Any slight variations in one will have an effect on the machining quality measures like surface roughness and material removal rate. In the present work Aluminium 7075 is used as matrix and activated charcoal with different percentage as reinforcement to fabricate metal matrix composites. The specimens are tested for Density, Hardness, Impact Strength and Ultimate tensile Strength. Best chosen samples are used to perform machining process in wire cut electrical discharge machine. 27 trials of experiments based on Response surface methodology are done and the observations are made. The quality of the machined samples is evaluated by the measurement of material removal rate and surface roughness. Results are utilized to develop the grey-fuzzy model. From this technique, the optimum combinations of process parameters are obtained and corresponding values of maximum material removal rate and minimum surface roughness are found out. From ANOVA analysis it is found that servo speed is the significant factor in determining the machining quality. Confirmatory experiments are performed to determine the effectiveness of the approach.