Experiment and numerical study of chip formation mechanism during cryogenic machining of Ti-6Al-4V alloy

The chip formation mechanism is a key factor in determining cutting stability and machined surface integrity. At present, the research on chip formation mechanism is mainly focused on conventional machining, while there is less research related to liquid nitrogen cooling conditions. In this paper, the chip formation mechanism of cryogenic machining is investigated based on the combination of liquid nitrogen external cooling milling experiments and cutting simulation with Ti-6Al-4V alloy as the research object. Firstly, the effect of cooling conditions and cutting speed on the degree of chip serration and chip micromorphology was analyzed based on orthogonal milling experiments. Next, the temperature and strain rate during chip formation were calculated and analyzed by simulation modeling. Finally, the formation of serrated chips under liquid nitrogen cooling conditions was modeled. The results show that the degree of chip serration increases under liquid nitrogen cooling conditions, and adiabatic shear and brittle cracking jointly dominate the formation of serrated chips. This research provides a reference and guidance for chip control in cryogenic machining processes.