A New Cutting Mechanics Model for Improved Shear Angle Prediction in Orthogonal Cutting Process

In metal cutting processes, accurately determining the shear angle is essential, as it governs chip formation and cutting force generation. Despite extensive research conducted on this topic, the accurate prediction of the shear angle remains a subject of ongoing investigation. This paper presents a new analytical model for predicting the shear angle, taking into account the direction difference between the shear stress at the boundary of the primary shear zone and the maximum shear stress. The constitutive property of the workpiece material with respect to the strain, strain rate, and temperature is considered in predicting the shear angle. The results show that the solution for the shear angle is not unique for a given rake and friction angle, and is highly dependent on the flow stress response of the workpiece material. Orthogonal cutting experiments were conducted on steel and aluminum alloys under various uncut chip thicknesses, cutting speeds, and tool rake angles to characterize the chip thickness and shear angle. Based on a comparison between model predictions, experimental results, and data from the literature for various workpiece materials and cutting conditions, it is shown that the proposed model results in an improved prediction for shear angle by considering the stress transformation within the primary shear zone.