Chip formation and morphology in cryogenic machining of Al-SiC composites

Machining aluminium matrix composites is a challenging and costly endeavour, primarily owing to silicon carbide reinforce particles, which are abrasive and hard, resulting in excessive tool wear, suboptimal surface quality, and undesirable chip formation. This study investigates the influence of cryogenic cooling on the development and morphology of chips when aluminium-silicon carbide (Al-SiC) composites are turned with an uncoated tungsten carbide cutting tool. Compared with dry machining, cryogenic cooling significantly alters the chip formation process, producing shorter and less curled chips. Chip breakability is mainly caused by cracks at the aluminium reinforcement particle interface, and the particle distribution is more uniform in cryogenically cooled chips. Rake and dual (rake and flank) cooling strategies have proven to be more effective for cryogenic cooling. Chip breakability primarily depends on the chip curl diameter across the used conditions. Chip formation under cryogenic cooling indirectly indicated the significant temperature reduction in the cut.