Experimental study on cryogenic milling performance of SiCp/Al composites with liquid nitrogen

Silicon carbide particulate-reinforced aluminum (SiCp/Al) composites is one of the typical difficult-to-cut materials, which are not suitable well for traditional machining any more. In order to explore new processing technology and verify its feasibility, this paper discussed the effects of cryogenic assisted milling with liquid nitrogen (LN2) coolant on the machinability of SiCp/Al composites. The effects of cryogenic milling were also compared with that of conventional dry milling. The results showed that cryogenic milling of 20% SiCp/Al composites would increase the surface hardness of the material, causing 15% higher amount of cutting force in cryogenic milling as compared to dry milling. In addition, there were serious tool feed marks on the machined surface under cryogenic condition because of the secondary cutting mechanism, which resulted in high surface roughness and poor surface quality. Overall, 46.73% higher roughness R-a and 31.53% roughness R-z were seen for cryogenic milling in comparison with dry milling technique respectively. The dish angle of milling tool and processing environment plays important roles in machined surface. Chip brittleness increased and short arc chips were formed in cryogenic milling. It was suggested that milling SiCp/Al composites under cryogenic condition had negative effects on the machinability of the material.