Effect of Machining of Aluminium Alloys with Emphasis on Aluminium 6061 Alloy – A Review

Abstract

Aluminium alloy is one of the most widely used engineering materials due to their relatively lower specific weight and corrosion resistance compared to steel. Besides, they are also relatively easier to machine. Aluminium alloys have been found to provide the highest degree of machinability compared to other lightweight metal such as titanium and magnesium alloys. Among every other type of aluminium alloy, the 6061 aluminium alloy has been used for general purposes due to some interesting attributes it possesses when compared to others. The investigation on the effect of machining condition on the corrosion of 6061 aluminium alloy has shown that the machining via electrical discharged provides better resistance to pitting corrosion than the diamond and carbide turning machine. Drilling, turning and cutting may influence the mechanical characteristics of the workpiece by producing hole opening around the low residual stresses and a small layer of extremely stressed material on the newly created surface, making it to become more prone to fatigue, crack propagation and corrosion at the stressed surface. The machining surface integrity has great influences on the fatigue lifetime of material since micro-cracks always initiate at the surface. The traditional machining techniques compared to the non-traditional or non-conventional techniques are more susceptible to the induction of poor surface integrity due to direct contact between the tool and workpiece which are characterised by several damage defects such as micro-cracks, surface hardening, roughness and residual tensile. This paper therefore provides an overview of the classes of aluminium alloys, there applications and machining of the alloys with a keen focus on 6061 aluminium alloy and exposition of various machining technique with both their beneficial and non-beneficial effects on the workpiece, tool life and the environment.