Modeling the cutting force with emphasis on the exiting stage of metal cutting

While many existing cutting force models achieve high predictive precision near the peak force, they frequently show substantial discrepancies in estimating the exiting moment during the tool’s exiting stage. Despite its significance, this issue has garnered little attention and remains poorly understood. To address this knowledge gap, this study introduces a theoretical framework to explain these discrepancies, attributing them to the interplay of negative shearing effects, flank face interference, and workpiece deformation during the exiting stage of the cutting process. In the proposed model, the minimum energy principle is employed as the criterion for determining whether a negative or regular shearing effect occurs. A slip-line field is developed to model the negative shearing effect and its generated cutting forces. Flank interference, caused by the rapid elastic recovery of deflected cutters during the exiting stage of the cut, along with its induced interference force, is found and modeled using a combination of force equilibrium principles and constraints related to friction and acceleration limitations. The deformed workpiece, which is associated with burrs, is treated to follow the volume invariance principle and rotate around the intersection point of the instantaneous negative shearing plane and the workpiece boundary. The final cutting forces corresponding to different exiting instants together with the actual exiting moment are successfully determined by combining the effects of the negative shearing-induced component and flank interference-related component. The proposed model is validated through a series of cutting tests.