Optimization of Wire EDM Process Parameters for Machining Hybrid Composites (356/B4C/Fly Ash) using Taguchi Technique

Abstract

Aluminium matrix composites (AMCs) are a class of advanced materials which have been developed for weight-critical applications. In addition they can be fabricated using conventional methods. In this study 356 Aluminium alloy is used as the matrix material for fabrication of hybrid AMCs by stir casting. Hybrid AMCs containing 1.5%, 3% & 4.5% boron carbide of average particle size 63 µm and 1.5%, 3% & 4.5% fly ash of average particle size 12 µm were fabricated. Optical micrographs of the composites show that the reinforcement particles were uniformly distributed in the matrix. WEDM is used to cut conductive materials of any hardness that are difficult or impossible to cut with traditional methods. WEDM is specialized in cutting complex contours or fragile geometries. High material removal rate and good surface finish cannot be achieved simultaneously. This is an important problem and continuous efforts are being made by various researchers all over the world. This research work attempts to develop an appropriate machining strategy for WEDM of hybrid AMCs using 0.25 mm diameter brass wire as the electrode. The five important process parameters such as gap voltage, pulse on time, pulse off time, wire feed and percentage reinforcement are taken as input parameters and material removal rate as the output parameter. The experiments have been carried out using the Taguchi’s L27 orthogonal array and analyzed using Signal to Noise (S/N) ratio analysis for finding the optimum process parameters. Analysis of Variance (ANOVA) is used to find the percentage contribution of the parameters and that of their interactions. The S/N ratio analysis results show that the gap voltage is the most significant parameter for obtaining higher MRR, followed by pulse on time and pulse off time. The parameters reinforcement and wire feed have no significance, since WEDM can cut material of any hardness.