Abstract: Based on the main failure mode of cemented carbide cutting tool and the influence of impact loading times on cutting tool reliability， a mathematical model on dynamic reliability of cemented carbide cutting tool was built by using the theory of stress-strength interference model and stochastic process， and the change rule of reliability was also obtained. On this basis， with impact loading times and machining time as the metrics respectively， the failure rate models were established. The results show that cutting tool reliability decreases gradually with the increase of impact loading times and machining time， and cutting tool failure rate characteristics of “bathtub” curve. According to this curve， the earlier， random and wear-out failure period of cutting tool can be divided accurately， that provides a theoretical basis for tool selection test， repair time and reliability life.

Key words: cutting tool, dynamic reliability, failure rate, critical fatigue stress, impact loading