Evaluation of tool wear when machining SiCp-reinforced Al-2014 alloy matrix composites

SiCp-reinforced metal matrix composites (MMCs) containing two levels of SiC particles (8 and 16 wt%) of different mean particle sizes 30, 45 and 110 μm were prepared using a melt stirring–squeeze casting route. Machining tests were carried out on the composites using uncoated and triple-layer coated carbide cutting tools at various cutting speeds under a constant feed rate and depth of cut. The effects of cutting speed and coating of tool on tool wear were investigated. Furthermore, surface roughness measurements were carried out on the machined surfaces. The reinforcement particle size and its weight fraction together with the cutting speed were found to be the major factors affecting the tool wear. Coated carbide cutting tools performed better than uncoated carbide cutting tools for all the materials machined in terms of tool wear. However, uncoated cutting tools produced better surface finish in terms of mean Ra values, particularly at lower cutting speeds. Although the tool wear mechanism remained one of abrasion, detailed examination of the cutting edges under scanning electron microscope (SEM) showed that higher cutting speeds led to edge chipping.