Analysis of thermo-mechanical cracking of ceramic tools in intermittent cutting

Intermittent cutting conditions can lead to the formation of cracks in ceramic tool materials. This paper deals with the calculation of thermal stresses initiated during the cutting and non-cutting period of a load cycle in face milling. A two-dimensional finite element model is applied to obtain the transient temperature and thermal stress distribution of the tool. It is found that compressive stresses dominate in the tool-chip contact area, whereas high tensile stresses exist directly underneath this area. The magnitude of stresses in the cooling part of a cycle is substantially lower compared to the cutting part. Further quantities effecting the stress situation are the tool material properties and the cutting conditions.