Reducing the friction of lubricated nonconformal point contacts by transverse shallow micro-grooves

Abstract

This study focuses on the effects of transverse shallow micro-grooves on the film thickness and friction of nonconformal contacts under relative motion. Experiments were conducted using a ball-on-disc tribometer equipped with high speed camera and torque sensor. The lubricated contact between the steel ball and glass disc represents a nonconformal point contact with elastohydrodynamic lubrication. The measurements of the film thickness were carried out using the optical interferometry technique while the friction was measured by a torque sensor on the ball shaft. The results reveal that the rubbing surfaces with transverse shallow micro-grooves with a length less than the diameter of the Hertzian contact have an improved tribological performance in comparison with smooth surfaces in the elastohydrodynamic lubrication regime. Indeed, a significant enhancement of film thickness has been observed using such design of microgrooves. On the other hand, the transverse deep and shallow micro-grooves with a length larger than the diameter of the Hertzian contact suffer from the side leakage and the lubricant is ejected out of the contact by sideways leading to a pressure drop and film thickness collapse. Moreover, the measured friction of surfaces textured with shallow microgrooves without intersection with the outer Hertzian circle is less than the friction of smooth surfaces in sliding and reversal motion.

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Artificial Surface Roughness Deformation in the Starved EHL Contacts

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Electrospun fibrous membranes for efficient heavy metal removal

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