Investigations of micro-textured surface generation mechanism and tribological properties in ultrasonic vibration-assisted milling of Ti–6Al–4V

Abstract

Ultrasonic machining (UM) as a non-traditional manufacturing technology has been recognized as an effective machining method for improving surface topography and surface quality. Although substantial experiment studies have been conducted and reported, the generation mechanism of textured surfaces in UM is still ambiguous, in which trajectories of tool-tips is not equal to actual cutting path due to separate-type cutting mechanism. Besides, the influence of ultrasonic vibration texture on tribological performance of machined surfaces is uncertain. This paper focuses on investigating the micro-texture generation mechanism and the effect of textured surface characteristics on tribological properties of machined surfaces in ultrasonic vibration-assisted milling (UVAM) process. Firstly, based on detailed analysis of tool-tips trajectories and rapid separate-type cutting process in UVAM, the generation mechanism of micro-texture was theoretically studied and the visualization of intermittent cutting process was given. Secondly, both conventional milling (CM) and UVAM experiments on Ti–6Al–4V were conducted to distinguish surface morphology features between CM and UVAM surfaces. Thirdly, the characterization methods of surface morphology, roughness parameters etc. were employed to characterize textured surfaces by comparing with CM surfaces. Finally, friction experiments were carried out to investigate influence of micro-texture on surface tribological properties, which was of great significance to functional property, wear property and service life of components. Experiment results showed that compared to common surfaces, uniform micro-texture could significantly improve surface morphology and surface quality. Friction test results also verified that micro-vibration-texture had a significant influence on improving tribological properties by reducing friction coefficients and its fluctuations.