Multi-objective Process Optimization to Improve Surface Integrity on Turned Surface of Al/SiCp Metal Matrix Composites Using Grey Relational Analysis

Abstract The utilization of Al/SiCp metal matrix composites in different engineering fields has undergone a tremendous increase due to its tailor-made properties that can be achieved by varying the size and volume fraction of reinforcement. However, the difficulty in machining of metal matrix composites (MMCs) arises not only from the excessive wear of the cutting tools but also from fracturing of the reinforcement particles which leaves pits and cavities. These characteristics in machining of MMCs affect the machined surface integrity. Hence, the objective of this study is to identify the optimum process parameters to improve the surface integrity on Al/SiCp composites. The machined surface integrity have been analysed as a function of processing parameters, such as feed rate, cutting speed, depth of cut and cutting tool geometry. Surface integrity is associated with surface roughness and sub surface damage. Both these response variables are governed by the cutting forces, surface finish, residual stresses generated on the machined surface and microhardness variation beneath the machined surfaces. Thus, to improve the surface integrity on Al/SiCp composites multi objective process parameter optimization is performed using grey relational analysis. Experiments on Al/SiCp composites of four different compositions are performed using L27 orthogonal array as per the Taguchi method. Analysis of experimental results indicates that the surface roughness is more sensitive to a change in size than a change in volume fraction of reinforcement. Investigations on sub-surface integrity involving micro-hardness variation have shown that depth of altered material zone (AMZ) changes with a change in size of abrasive reinforcement in MMCs. The grey relational analysis shown that wiper insert geometry with 0.8 mm tool nose radius, 0.05 mm rev-1 feed, 40 m min-1 cutting speed and 0.2 mm depth of cut are optimized machining conditions that enhances the surface integrity on Al/SiCp composite within the scope of the experiments performed.