The effect of workpiece temperature on the machinability of an aluminum/SiC MMC

Metal matrix composites (MMCs) are becoming an increasingly important class of engineering material which are finding applications both in the automotive and aerospace industries. However, their machinability is regarded as poor due to the severe abrasive tool wear observed during machining. Prior to an investigation into the laser-assisted turning of an aluminium/silicon carbide MMC, the machining behaviour of the material after pre-heating to 200, 300, and 400 degrees C was investigated. The results indicated that at cutting speeds from 20-90 m/min the wear rate increased with increasing workpiece temperature although the wear mechanism remained one of abrasion. The presence of a built-up edge (BUE) was noted and a strong correlation found between its presence and the amount of wear produced. The results of this work show that within the range of parameters investigated, the pre-heating of the MMC had a detrimental effect on its machinability.