Grinding of magnesium/Y2O3 metal matrix composites

The advanced metal matrix composites are finding high technology applications in aerospace and automotive industries because of their light weight coupled with high specific strength. Although advances have been made in near-net-shape technology, a finishing operation is needed to achieve the required dimensional tolerance and good surface finish. Magnesium especially experiences problems during grinding owing to its ductility and fire hazardous nature. Though grinding is not preferred for a pure magnesium matrix composite, owing to their increased hardness necessitate grinding, an attempt was made to perform grinding on the magnesium yttria composites with commercially available alumina and silicon carbide wheels. Grinding of magnesium composite was carried out by varying process parameters, such as wheel peripheral speed, workpiece velocity, and depth of cut. During the process the forces were monitored by a piezoelectric dynamometer. The performance of the grinding was studied by analyzing and comparing the grinding forces, specific grinding energy, and the average surface roughness. The ground surface was analyzed using optical and scanning electron microscopy. The grinding forces were observed to be decreasing with the increase in hardness, which in turn resulted in smooth surfaces. The obtained surface roughness (Ra) values were in the range of 0.6-1.3 mu m.