Tribological aspects of machining aluminium metal matrix composites

In this paper, tool wear, surface integrity and chip formation are studied under both dry and wet cutting conditions. The turning results showed that the influence of coolant on tool life was more pronounced at higher cutting speeds than at lower cutting speeds. This is mainly because of the dominance of the mechanical wear mechanisms at lower cutting speeds and the lack of formation of a lubricating layer/film that can reduce the friction between the abrasive particle and the cutting tool. When turning at higher speeds, under wet conditions, the tool life was increased. However, the surface quality was deteriorated. This was mainly due to the flushing away of the partially debonded particulates from the machined surface, thus, forming higher percentage of pit holes and voids. The formation of chips with serrated edge was more pronounced during wet cutting, as a result of high thermal gradient. The microhardness measurements on the aluminium matrix beneath the machined layer showed higher values when cutting under wet conditions.