Enhancement of Surface Roughness and Corrosion Resistance of Wedmed Al 7075 Alloy

Abstract

An alloy of Aluminium has good properties and strong would be ideal for many applications. Among all the series of aluminium alloys, Al 7075 is extensively used in aircraft structures, gear shafts, and automotive industry because of its high strength and good corrosion resistance. The machining of Al 7075 can be done under annealed conditions and lubricants are used for operations. In the present work, Al 7075 was machined by using Wire Electric Discharge Machine (WEDM) and investigated the effect of operating parameters on reponses. The surface roughness and corrosion resistance are considered as responses. The operating parameters of WEDM considered in this work are pulse ON time, pulse OFF time, wire feed and servo voltage. Experiments were conducted according to the Taguchi’s design of orthogonal array L18 (21 x33 ). The values of surface roughness and corrosion pit potentials were observed for each experiment to understand the relationship. Multi-objective optimization for these process parameters has been carried out by Grey Relation Analysis (GRA). From this technique, the optimum combination of process parameters are obtained and corresponding values of surface roughness and corrosion pit potentials are found out. To validate the response table for grey relation grade obtained from GRA, Taguchi analysis was carried out which shows that the pulse on time is the most influencing parameter followed by pulse off time, wire feed and servo voltage.