Optimization of Drilling Operation Using Work Material Al 7075 Alloy Reinforced with Boron Carbide

In the present study, a metal matrix composite containing Al 7075 alloy and boron carbide (6% wt) was fabricated with the help of stir casting method. After the fabrication of the composite, the drilling operation was done on the conventional radial drilling machine, manufactured by Atlas Engineering Co. London. The dimensions of the work piece samples were 75 mm × 75 mm × 25 mm. The drill sizes were 5, 6.5, and 8.5 mm in diameter. The drills bits used were of HSS manufactured by Miranda Gold (India). Feed rate, speed, and drill bit diameter were chosen as process parameters. For the design of experiment, Taguchi's L9 orthogonal array was used with three level of factor. For finding out the optimum level of process parameters for multi-performance characteristics that is MRR and surface roughness, grey relational analysis was used. After optimization, it was found that the largest values of grey relational grade for feed rate, spindle speed, and drill diameter are at the level 740 rpm, 0.015 in/rev, and 5 mm, respectively. Hence, these are the recommended levels of process parameter when better MRR and optimum surface roughness have to be obtained simultaneously.