It was found by cutting, in the cutting process, mechanical loading and thermal stress, while the presence of the tool, whereby the tool may cause compressive plastic strain. Such plastic deformation may occur in the tool-chip contact region the highest temperature portion, which portion is located within a certain range of the cutting edge on the back. In view of the generation of cracks means that there is tensile stress, tensile stress can be speculated that these elastic body by the external force is applied to the plastic deformation zone during the cooling phase of the cutting cycle caused. This analysis results can be verified in accordance with the facts crack initiation in the back of a range of cutting edge.

     According to observations, damage in the form of tools, there are two: ① cutting edge chipping; ② rake between two cracks between localized spalling. In the intermittent cutting process, the tool chipping occurs reasons not yet clear, but it may not have relations with the thermal stress, because chipping phenomenon also occurs at low speed cutting. However, cracks in the cutting edge in the vertical direction to produce thermal stress may occur related to two thermal cracking of ceramic materials is a well known fact, but because of the presence of various types of cracks staggered, so the heat does not seem to crack the direct cause of the ceramic tool breakage . However, for carbide cutting tools, when peeling between that part of the crack between the two rake occur, often directly caused by thermal cracking tool breakage.

     With the tool - workpiece thermocouple to measure the temperature found in the course of the cutting cycle, the maximum and minimum cycle temperature is kept constant, and is not affected by the type of spacer used. Therefore, thermal stress generated by compression in the cutting process can be controlled by the volume of the blade temperature. Before the start of the carbide cutting preheat treatment can reduce the high initial compressive stress, which will help improve the performance of the tool.