Investigation of Workpiece and Tool Surface Quality in Electro Discharge Machining of Al 5083 Alloy Produced by Powder Metallurgy

Abstract

Aluminum alloys are widely preferred in various fields such as aerospace, ship and automotive due to their lightness and relevant production cost. In this study, electro discharge technique was used in the processing of aluminum 5083 alloy (Al5083) produced by powder metallurgy method. The surface quality resulting from the experiments was investigated in terms of Ra, Rz and Rsm. Experimental studies were carried out according to Taguchi L9 orthogonal experimental design, using three different levels of discharge current, pulse on time and pulse off time parameters. As the discharge current increased, Ra and Rz increased, Rsm first decreased and then increased. As the pulse on time increased, Ra and Rz first increased and then decreased, and Rsm increased. When the pulse off time increased, Ra and Rz decreased and Rsm increased. As a result of the analysis of variance (ANOVA) performed to determine the effect rates of the variable parameters on the surface quality, the order of importance of the parameters was found to be discharge current, pulse off time and pulse on time. The effect of discharge current, which is the most effective parameter according to ANOVA, on Ra, Rz and Rsm was calculated as respectively 70.87%, 70.41% and 36.34%. Microscopic images taken from the tool (copper) and workpiece surface show that the craters and peaks formed by the spark effect are formed on both material surfaces.