Thermal cracks due to heating-cooling cycles in intermittent cutting in the machining processes of bearing production play an important role in tool life. This paper discusses restraint in the tool failure of TiC cermet used in actual machining line. The purpose of this study is to investigate two effects the appearance of the rake face and variation in the feed rate in thermal cracks on machining lines and to examine the thermal crack mechanism. As a result, we found that tools with some micro cracks were easily damaged. Removing some cracks on the rake face delays thermal crack generation time and reduces the number of cracks. Slightly decreasing the feed rate has a good effect on restraining the occurrence of cracks due to lowering of the cutting temperature.

1. [1] Handbook of Precision Machining, Corona publishing Co., Ltd., p. 71, 1992. (in Japanese)
2. [2] K. Uehara K and Y. Kanda, “Fundamental Approach to the Thermal Crack of Cermet Cutting Tools,” Ann. of CIRP, Vol.30, No.1, pp. 47-51, 1981.
3. [3] K. Okushima and T. Hoshi, “Thermal Crack in the Carbide Face-Milling Cutter (1^st Report),” J. of JSME, Vol. 27, No. 178, pp. 843-852, 1961. (in Japanese)
4. [4] N. Shinozaki N, “Thermal Cracks of Carbide Face Milling Cutter,” J. of JSME, Vol.5, No.20, pp. 753-764, 1962.
5. [5] T. Sugita, “Thermal Cracks in Ceramic Face Milling Cutters (1st Report),” J. of JSPE, Vol.30, No.8, pp. 662-670, 1964. (in Japanese)
6. [6] T. Ihara, T. Shirakashi, and E. Usui, “Analytical Prediction of Cutting Edge Chipping in Interrupted Turning Operation (4th Report),” J. of JSPE, Vol.48, No.6, pp. 757-763, 1982. (in Japanese)
7. [7] S. M. Bhatia, P. C. Pandey, and H. S. Shan, “Failure of Cemented Carbide Tools when Excutting Intermittent Cuts,” J. of ASME, Vol.101, No.4, pp. 391-396, 1979.
8. [8] Y. Yamane Y and N. Narutaki, “The Effects of the Atmosphere on Tool Failure in FaceMilling (2^nd Report),” J. of JSPE, Vol.49, No.4, pp. 521-527, 1983. (in Japanese)