Abstract: In this paper, according to the theory of brittle fracture and applying the Boundary Element Method the stress field and the propagating path of crack in the outing zone of glass cutting are calculated, and then two cutting models, one for large undeformed chip thickness and another for small punde formed chip thickness, have been constructed. These two models re verified by experimental results. Based on these two models the following topics are discussed and explained: The mechanism of the formation of various categories of chip; The mechanism of the formation of machined surface; The relation between the chip appearance and the machined surface roughness, cutting force, and the wear of outing tool.

Key words: Cutting, Glass, Surface roughness