Experimental and numerical investigation of the breakage of a cutting tool with ultrasonic vibration

In this study, first, the breakage of a cutting tool with ultrasonic vibration was investigated using a scanning electron microscope. It was concluded that the breakage of a cutting tool with ultrasonic vibration has the features of fatigue fracture; i.e. it undergoes three stages: micro-crack generation, micro-crack spreading, and brittle fracture. Second, the reasons for the breakage of the cutting tool with ultrasonic vibration were analysed theoretically. The analytical results demonstrated two reasons: one is that the pulsating main cutting force and pulsating frictional force act periodically on the rake face of the cutting tool; the other is that the flank of the cutting tool is alternatively subjected to compressive stress and tensile stress. Furthermore, the influences of the main factors on the breakage of the cutting tool with ultrasonic vibration were studied experimentally. Finally, the breakage of the cutting tool was analysed using the finite element method (FEM). FEM simulation results demonstrate that the fatigue life and fatigue safety factor of the cutting tool decrease and the fatigue damage coefficient of the cutting tool increases with the increase in the amplitudes of the pulsating loads, reciprocating frictional force, and normal force.