Surface Texturing Technique Based on Ultrasonic Turning for Improving Tribological Properties

Tribological properties such as lubrication, friction, and wear resistance greatly affect machine operation efficiency, performance, and service life. Surface texturing methods such as scraping can be used to improve these properties. Scraping creates many small depressions on the target surface. These depressions, which are evenly distributed, function as oil holes and thus improve lubrication performance. This paper describes a surface texturing technique based on ultrasonic vibration-assisted turning (UVAT) that simultaneously improves tribological properties and machinability. In UVAT, the cutting tool is oscillated mainly in the principal direction. Vibration in the radial direction, which is induced by Poisson deformation, periodically digs up or pushes the workpiece surface in the radial direction, creating a textured surface. A surface subjected to UVAT has periodic depressions along the workpiece rotation direction. The texturing rate of UVAT is up to 6700 mm2/min, which is higher than that of manual scraping. To evaluate the tribological performance of a surface textured by UVAT, the friction coefficient between a stainless steel pin and the surface was measured under oil dipping conditions. The results of friction experiments show that the friction coefficient of the UVAT-treated surface and its fluctuation were lower than those of a conventional turned surface. The UVAT-treated surface had stable friction properties.