Friction interface characteristics are key determinants of the output performance of ultrasonic motors (USMs). This study aims to enhance the frictional properties between the stator and rotor and thereby improve the output performance of USMs.
This study takes the traveling-wave ultrasonic motor 60 (TRUM-60) as the research subject and employs polyimide (PI) material as the friction medium. Using laser micromachining technology, circular textures and composite circular-elliptical textures were fabricated on the friction interface. The influence mechanisms of the composite surface textures on the tribological properties and motor output performance were systematically investigated.
Experimental results indicate that, compared to the non-textured surface, the composite texturing process significantly increases the interfacial coefficient of friction (COF) by 34.36%. By optimizing the preload, the motor’s energy conversion efficiency improves by 5%. Notably, under a preload of 240 N, the optimal output characteristics are achieved, with the energy conversion efficiency reaching 51.4%. Within the 0.5–1.2 N·m operating range, the efficiency remains stable above 50%, and the effective operating range expands by 83%.
Investigations reveal that composite textures not only collect debris and increase the contact area between micro-protrusions and textured edges but also optimize friction properties through the synergistic effect of the two texture types: (1) The long-axis orientation of elliptical dimples forms directional lubrication microchannels, effectively facilitating debris removal; (2) The isotropic distribution of circular dimples enhances the secondary lubrication effect. After introducing composite textures, the increased interfacial COF effectively improves the driving torque of the ultrasonic motor, optimizes shear force distribution, and enhances overall output performance.
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2025-0421/
