Abstract: A model for formation of forward burrs and fractures in orthogonal cutting is developed. Distinguish criterions of forward burrs and fractures are given and the main factors which influence limit transformation of forward burrs and fractures are experimented and studied. The results show that the limit change condition of forward burrs and fractures is: shear strain ε≤3, fracture area; 3＜ε＜4, transition area; ε＞4, burr area. And the limit transformation condition of forward burrs and fractures change with the cutting condition, which lay scientific basis of further research on cutting burrs formation and its deburring technology.

Key words: Cutting burr, Metal cutting, Shear strain