Machinability Studies on the Turning of Magnesium Metal Matrix Composites

Magnesium-based MMCs are widely used in structural-based applications due to their lightweight, high hardness, corrosion and wear resistance. Also, machining is an important manufacturing process that is necessary to ensure dimensional accuracy and produce intricate shapes. In this context, the machining of Magnesium based metal matrix composites is undertaken to study the impact of the cutting parameters on the machinability behaviour. In this work, turning of pure Mg/SiCp on a Lathe is done and an in-depth assessment on the machining forces, machined surface quality, chip microstructure, and tool morphology has been carried out using TiAlN coated tooling insert. The analysis revealed that the thrust force decreased due to the thermal softening of the matrix meanwhile the feed force also followed the similar trend at higher cutting speeds because of the minimized built-up edge and cutting depth whereas principal cutting force was inconsistent at higher cutting speeds. The surface finish was better at high cutting speed - low feed combination. The chip microstructure revealed that gross fracture propagation at the free surface and variations in the shear bands have occurred at different cutting speeds. Tool studies using SEM analysis revealed wear modes like chipping and built-up edge at low cutting speeds, but with a reduced impact at intermediate cutting conditions, whereas abrasion wear was observed predominantly in the tool nose at higher cutting speeds.