Investigations on the effect of dielectric medium and WEDM parameters on surface characteristics of Al 7068 (ordnance aluminium) alloy

Abstract

The current experimental work focuses on determining the optimum machining parameter combination for machining AA7068 in wire electrical discharge machining (WEDM). WEDM is a promising advanced machining technology, capable of processing complex-shaped components, machining hard/heat treated materials, and cutting conductive ceramics that are complicated to machine using traditional methods. Taguchi’s L18 orthogonal array is adopted to conduct the experiments by considering dielectric medium, pulse on time, pulse off time, peak current, gap voltage, and wire feed as input factors. The output responses like surface roughness, material removal rate, micro hardness, recast layer, surface morphology of the machined surfaces and wire tool were considered for study. The ANOVA method was used to analyse the impact of individual processing parameters on material removal rate and surface roughness. Microhardness of the cut surface was studied using Vicker’s method. Besides, scanning electron microscopy (SEM) and Energy Dispersive X-Ray analysis are conducted to examine the surface characteristics and elemental composition of the machined working piece at various cutting parameters (EDX). TOPSIS method is chosen to identify the optimal parametric conditions. From the results, the optimum condition achieves surface roughness (3.684 μm) and material removal rate (5.106 mm3 min−1) respectively.