Adiabatic shear in chip formation with negative rake angle

The mechanics of chip formation in grinding is investigated based on thermo-elastic-plastic finite element simulations of orthogonal cutting with a large negative rake abrasive-grits. The modeling is coupled with temperature and strain-rate-dependent flow stress characteristics of a work material SK-5 (0.93%C carbon steel). The shape of chip calculated is affected by the cutting speed and the undeformed chip thickness. In high-speed cutting, serrated chip formation caused by adiabatic shear, which is usually observed experimentally under the cutting conditions of grinding region, is obtained analytically without any consideration of crack propagation. Temperature and flow stress calculated in the primary shear zone vary periodically according to the segmentation of serrated chip. Then changes in temperature, flow stress, strain rate and strain at a material point fixed to and moving with chip is monitored in order to investigate the chip formation process. This clarifies the cutting mechanisms of different types of chip formation with negative rake.