Effect of High-Speed Longitudinal Ultrasonic Vibration-Assisted Milling on Tribological Characteristics of a Plane Surface

Ultrasonic vibration-assisted machining is a widely used method in recent times to improve the tribological performance by lowering the friction coefficient and increasing the wear resistance of sliding components. The present study experimentally investigates the tribological performance of longitudinal ultrasonic vibration-assisted milling (LUVAM) and conventional milling (CM) surfaces in starved lubrication environments. During the LUVAM process, high-frequency vibration (40.4 kHz) with a low vibration amplitude (≈1.2 µm) was applied on the milling tool to generate uniform surface textures on the surface. The introduction of surface texture using the LUVAM process makes the surface hydrophobic in nature as compared to the corresponding CM surface. The LUVAM surfaces showed improved friction behavior as compared to the CM surfaces when machined at high feed rate values and under high applied load and sliding speed conditions. In addition, the LUVAM surface had a lower specific wear rate at high sliding speed and high applied load conditions for the surfaces generated at high feed rate values. The retention of lubrication oil in between surface textures and the flow back of this lubricant oil into the contact area because of hydrodynamic pressure produced by the applied load turned out to be the main reason for the improved tribological behavior of LUVAM surfaces at high applied load and sliding speed conditions.