Characterization of Electric Discharge Machining of AA7075/5B4Cp/5Gr Hybrid Composites Utilizing Copper as Electrode under various Di-electric Conditions

Abstract

Metal matrix composite (MMC) of Aluminium 7075 reinforced with 5wt% of B₄C particles and 5wt% of Graphite were manufactured by stir casting. The influence of Cu tool by different EDM process variables viz. pulse current (3 – 15amp), pulse on time (20 - 100µs) with open circuit voltage (40V) on surface roughness (µm), Tool wear rate (gm/min) and material removal rate(mm3/min) under various dielectric conditions(Used engine oil, Al₂O₃ + used engine oil, EDM oil and Al₂0₃ + EDM oil) have been considered. The output characteristics of surface roughness (Ra) and topography using SEM, material removal rate (MRR) and Tool wear rate (TWR) of machined samples showed significant improvement when used engine oil mixed with Al₂O₃. Micro globules, miniscule re-melted layers and micro cracks were observed in surface topography.

Keywords- Power Mixed Electric Discharge machining (PMEDM); Wealth from waste; Di-electric fluids; Aluminium composites; surface topography