Optimization of wire EDM process parameters on Al6061/Al₂O₃ composite and its surface integrity studies

Abstract

Metal matrix composites (MMC) are finding application in many fields such as aerospace and automobile industries. This is due to their advantages such as light weight and low cost. Among all the available non-traditional machining processes, wire electric discharge machining (WEDM) is found to be a suitable method for producing complex or intricate shapes in composite materials. In this study, an aluminum metal matrix composite (AMMC) with 6% and 8% weight (wt) fraction of Al2O3 is prepared through the stir casting process. The fabricated AMMC specimen is machined using WEDM, considering various process parameters such as wt % of reinforcement, gap voltage (Vg), peak current (IP) wire tension (WT) and dielectric pressure (Pd). Output responses such as the machining rate (MR) and surface roughness (Ra) of the slots are analyzed by conducting L18 mixed orthogonal array (OA) experiments. The experiments are analyzed using techniques for order preference by similarity to ideal solution (TOPSIS) and analysis of variance (ANOVA). Based on the analyses, the optimum combination of process parameters for better MR and Ra is as follows: wt % = 6 gm, Vg = 53 V, Ip = 8 A, WT = 11 g, Pd = 13 bar. The optimum level of process parameters for MR and Ra are 1.5 mm/min and 3.648 µm, respectively. Based on ANOVA, the peak current is found to have a significant influence on MR and Ra. Moreover, based on a scanning electron microscope (SEM) image, the presence of micro-ridges, reinforcement, micro-craters, micro-cracks, recast layers and oxide formation are all analyzed on the surface being machined.

Keywords

• aluminum metal matrix composite (ammc)
• aluminum oxide
• recast layer
• oxide formation
• micro-crack length and micro-craters