Study on the tool-chip friction coefficient of the bottom edge in high-speed internal cooling spiral milling hole

The main focus of this work is the effect of the third body on the friction coefficient of the bottom edge tool chip in spiral milling with internal cooling at high speeds. The maximum pressure of the tool-chip contact and the tool-chip friction factor of the bottom edge are estimated by evaluating the helical milling principle and milling experiments. Moreover, the Hertz-Mindlin with bonding discrete element model (DEM) is established and corrected. According to the discrete element model and the morphology of the machined surface and the bottom edge, the friction coefficient of the bottom edge tool chip in high-speed internal cooling milling decreases with an increase in third bodies. The bottom edge’s friction coefficient is lowered by adding third-body particles. The third body increases with spindle speed but decreases with increased pitch. The research results provide a reference for studying tool-chip friction coefficient in high-speed internal cooling helical milling.