In Situ Investigation of the Tool–Particle Interaction During Orthogonal Cutting of SiCp/Al Composite

Abstract Machining of silicon carbide particle-reinforced aluminum matrix (SiCp/Al) composites is challenging due to the complex interactions between the cutting tool and silicon carbide (SiC) particles, which critically affect surface integrity. This study employed an in situ imaging approach to directly investigate the kinematics of individual SiC particles during the orthogonal cutting process. Through direct observation, three primary particle behaviors (pressed-in, cut-off, and pulled-out) were systematically categorized. In addition, several associated phenomena were identified, including particle fracture initiating before tool contact, localized extrusion of the Al matrix around the pressed-in particles, and surface scratching caused by particles near the tool tip. Particle tracking confirmed that the pressed-in category is the most dominant interaction. To systematize these findings, novel positional criteria were established to distinguish the three primary behaviors. Furthermore, fractures within the cut-off category were sub-categorized into pre-splitting, cracking, and crushing. Direct in situ observations, corroborated by statistical analysis of crack orientations, revealed that particle cracks propagate predominantly normal to the particle–tool contact surface. Scanning electron microscopy examinations established a correlation between the particle pressed-in behavior and the formation of cavity and crater defects on the machined surface. The work provides direct experimental evidence for the study of the fundamental mechanisms of material removal and surface generation in SiCp/Al machining.