Abstract: In the interrupted cutting process， the main failure mode of the indexable cutting tool is endurance failure. The selection of design parameters of the cutting tool is important， which has direct effect on its reliability. A mathematical model of the dynamic reliability for hard alloy cutter was successfully built based on the stressstrength interference model， and the change rule of its reliability in the machining period was also obtained. Combining with sensitivity analysis method， the computational formulas of the dynamic reliability sensitivity and the change curves of design parameters were derived. The study shows that due to the different sensitive degree of design parameters to the cutting reliability， the selection of sensitive parameters should be controlled so as to improve reliability of the cutting tool and the accuracy of the processed accessory. Meanwhile， the proposed method provides a theoretical basis for enhancing the reliability of the tool system and the whole machine tool.

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