The role of tool edge geometry on material removal and surface integrity in cutting metal matrix composites

Metal matrix composites (MMCs) possess excellent material properties due to the combination of metals and reinforcing phases, yet this reduces their machinability. Numerous studies have shown that, due to the ploughing effect of the cutting tool, the edge effect can directly impact the material removal mechanism and the generation of surface integrity. However, the influence of different cutting-edge geometries on the cutting phenomena of MMCs has not been comprehensively investigated. This study explored the effects of three cutting-edge geometries (sharp, rounded, asymmetric) on the mechanisms of material removal and surface integrity under different uncut chip thicknesses (UCT) in orthogonal cutting of Al/SiCp. The results indicated that the altered cutting edge caused by dead metal zone (DMZ) played a dominant role in the material removal mechanisms of MMC. While cutting force was primarily affected by edge geometry, it showed minimal variation. Chip morphology varied with UCT, transitioning from long and continuous chips to more fragmented chips as UCT increased. Surface and subsurface defects worsened at higher UCT, with limited differences due to edge geometries. The DMZ formation transformed the blunt edge into a relatively sharp one, eliminating the effect of edge geometries. This effect became more pronounced as UCT increased and persisted even under small UCT and sharp edge conditions. Besides eliminating the edge effect, the DMZ introduced a lateral fish-scale-like surface defect, significantly compromising post-cutting surface integrity.