Impact of SiC Particle Incorporated Dielectric Medium on Machining Performance of AA7050/SiC/Al2O3 Hybrid Composites

Abstract

The component produced with best surface quality increases the life time of the product and with the objective of attaining it AA7050 hybrid composites was processed using the Electric Discharge Machining (EDM) technique. The composites with varying weight percentage of reinforced particles (2, 4, 6, 8 wt%) was manufactured using the stir casting technique, with SiC and Al2O3 as reinforcement and uniform dispersion of particles were confirmed through SEM with EDS mapping. EDM experimentations were conducted on the composites by varying the Pulse on Time (Ton), Current (A), Powder concentration and reinforcement weight percentage and the experimental runs were being designed using the Taguchi mixed orthogonal array, Whereas Material Removal Rate (MRR), Tool Wear Rate (TWR), Surface Roughness (Ra) and Machined Surface Hardness (MSH) were recorded as response. The MRR increased from 38.72 mg min−1 to 73.67 mg min−1 when SiC particles were incorporated in the dielectric fluid attributed to the fact that generated heat was uniformly dispersed throughout the machined surface due to the low thermal conductivity of SiC particles. When powder particles were incorporated, TWR for composites machined with 2 wt percent reinforcing materials increased substantially to 32.61 mg min−1. Because of the high density of SiC particles (4.36 g cm−3), the scattered particles settled throughout the machined surface, reducing the surface quality by 12% with particle inclusion. Black spots, remelted particles, globules and micro pits are some of the textures observed on the machined surface morphology.