Effects of separating characteristics in ultrasonic elliptical vibration-assisted milling on cutting force, chip, and surface morphologies

Vibration-assisted cutting is considered a feasible way to cope with difficult-to-machine materials. Within the present paper, ultrasonic elliptical vibration-assisted milling (UEVM) is adopted to the machining of Ti-6Al-4V titanium alloy. Velocity coefficient K is introduced to describe the separating characteristic of the UEVM. Theoretical analysis of separating type and non-separating type cutting using the UEVM method is performed. Subsequently, experimental investigations of cutting force, chip formation, and surface morphology are conducted by comparing the UEVM with the conventional milling (CM). Results show that compared with non-separating type UEVM, separating type UEVM can bring more reduction of average radial cutting force and the chips are visibly thinner under the UEVM condition with K < 1 than those produced under CM condition using the same cutting parameters. However, the surface roughness in the UEVM is significantly larger than those in the CM due to the periodic motion component of the teeth of milling tool in the direction perpendicular to machining surface with the application of ultrasonic elliptical vibrations.