An investigation of surface roughness formation in ultra-precision machining of Al6061/SiC_p metal matrix composites

This paper deals with an investigation of the process factors and the material factors affecting the surface roughness formation in ultra-precision machining of Al6061/15SiC_p metal matrix composites. The process factors involve machining conditions such as the spindle speed, feed rate and depth of cut. The material factors considered are the presence of SiC reinforcement, the swelling of tool marks as well as the surface integrity such as pits and cracks. Experimental results indicate that pits and cracks are formed on the cutting surfaces in ultra-precision machining of the composites. The amount of pits and cracks increases with decreasing spindle speed and increasing tool feed rate. Under low spindle speed condition, the amount of pits and cracks are found to increase with increasing depth of cut whereas these are not noticeable at high spindle speed condition. Significant swelling of tool marks is also observed under various cutting conditions. This finding is further confirmed with the use of power spectrum analysis technique.