Abstract: In this paper, the concept of material on the edge section is put forward for the first time. It is believed that the flow layer and built-up layer on the face and flank, the additional chip, the built-up edge and the scale are all derivatives from the material on the edge section. Stress state of the material on the edge section is analysed and a stress model is given. The conditions which the various derivatives result from are also studied in this paper.