A Study of Influence Factors on Form Error and Surface Finish in the High-frequency Ultrasonic Vibration-assisted Cutting of Structured Surfaces

Ultrasonic vibration-assisted cutting (UVAC) is able to improve material machinability. For an ultrasonic tooling system, vibration amplitude is a key factor to be controlled which has significant effect on tool trajectory, cutting ratio, lubrication condition, etc. It plays an important role in affecting the form error of the workpiece being machined. In this paper, the high-frequency ultrasonic vibration-assisted cutting (HFUVAC) system, UTS2 with a frequency of 104 kHz is used to study influence factors including vibration amplitude, slope angle of the target profile and workpiece material on form error and surface finish of the structured surface. The input current which is in proportion to vibration amplitude is set as 20, 30 and 40 mA with an amplitude of about 0.5 - 1.0 μm, to machine cosine structures with various maximum slope angles on easy-to-machine material (copper alloy) and hard-to-machine material (steel), respectively. An analytical and experimental investigation has been conducted. The results show that slope angle of the target profile and workpiece material have a larger effect on form error than vibration amplitude. In HFUVAC of hard-to-machine materials with a higher hardness, form error increases significantly with increasing slope angle of the target profile, due to less cut of material caused by indentation effect in the downhill profile.