Research on tool wear mechanism of liquid nitrogen internal cooling machining

Due to its low temperature, high cooling efficiency, environmental friendliness, and other advantages, liquid nitrogen cooling machining is frequently employed in the processing of difficult-to-machine materials. Currently, liquid nitrogen cooling is most commonly performed using liquid nitrogen flood cooling. However, scholars hold differing views on the results of tool wear. This study uses Ti-6Al-2Zr-1Mo-1V titanium alloy as the subject to analyze tool life and wear mechanisms under four different cooling conditions: Dry cutting, Wet cutting (using cutting fluid), LN 2 flood cooling, and LN 2 internal cooling. The results demonstrate that although liquid nitrogen cooling does not exhibit a significant lubrication effect, internal cooling with liquid nitrogen provides more stable and efficient cooling, effectively inhibiting tool adhesion and oxidation wear. Additionally, it reduces the influence of the Leidenfrost effect , significantly improving tool life. Furthermore, it is shown that the method of applying liquid nitrogen as a cooling medium significantly impacts tool wear outcomes. Overall, liquid nitrogen internal cooling is a viable approach for enhancing tool life during the machining of difficult-to-machine materials. • Different LN 2 application methods on tool wear characteristics were investigated. • The impact of the Leidenfrost effect on tool wear was analyzed. • The tool wear mechanism in machining with internal cooling by LN 2 was revealed. • Liquid nitrogen cooling lacks lubricating effect.