11. Ultrasonic Vibration Assisted Cutting of Tungsten Carbide

In this chapter, ultrasonic vibration assisted cutting is conducted to investigate the effect of various cutting conditions such as vibration mode and amplitude, diamond type, cutting speed, feed rate and depth of cut, on ductile mode cutting of tungsten carbide such as critical depth of cut, cutting force, chip formation, tool wear and surface integrity. Cutting forces are measured using a three-component dynamometer, critical depth of cut is measured using a stylus profilometer, machined surface integrity and chip formation are examined using an SEM, and tool wear is examined using an OMIS. It is found that critical depth of cut for the transition from ductile mode cutting to brittle mode cutting in 1D ultrasonic vibration assisted grooving is several times larger than that in the conventional grooving. Lower thrust directional amplitude in 2D ultrasonic vibration leads to less brittle fracture generated on the machined surface of tungsten carbide, and 1D ultrasonic vibration with no thrust directional vibration leads to minimum brittle fracture and less diamond tool wear. Nano-polycrystalline diamond with isotropic mechanical properties does not perform better than single crystal diamond as tool material in terms of tool flank wear in ultrasonic vibration assisted turning of tungsten carbide. Radial cutting force F_x is much larger than tangential cutting force F_z and axial cutting force F_y. Cutting speed has no significant effect on ductile chip formation mode. Ductile mode cutting is achieved when maximum undeformed chip thickness is smaller than a critical value. And the larger critical depth of cut for 1D ultrasonic vibration assisted grooving of tungsten carbide implies that ultrasonic vibration could be used to improve ductile mode cutting performance of brittle material.