Enhancement of machinability and surface quality of Ti-6Al-4V by longitudinal ultrasonic vibration-assisted milling under dry conditions

Longitudinal ultrasonic vibration-assisted milling (LUVAM) was performed to improve the machinability and surface quality of titanium alloys Ti-6Al-4V under dry conditions. Effects of ultrasonic amplitude on the three-component cutting forces, cutting temperature, surface topography and 3D surface roughness (Sa and Sq) were investigated. The results show that, the cutting forces in both longitudinal and feed directions decrease with the increasing amplitude from 0 to 6 µm, as well as the average and maximum cutting temperature. Accordingly, the surface topography of Ti-6Al-4V becomes more uniform when ultrasonic amplitude reaches to 6 µm. Sa and Sq decrease by 35.1% and 34.0%, respectively, when the ultrasonic amplitude increases from 0 to 6 µm. The machinability and surface quality of Ti-6Al-4V are improved via this dry LUVAM, duo to the thermal-mechanical coupling resulted from large-amplitude ultrasonic vibration. The established approaches have potential applications in dry or near dry cutting of difficult-to-machine alloys with LUVAM.