Analysis of the Film-Forming Characteristics of Water Lubrication Assisted by Small Amount of Secondary Lubricating Oil

Abstract This study investigates the film formation mechanism of lubrication using a small quantity of lubricating medium in a water environment. A roller-on-disc test rig combined with a fluorescent technique is employed to directly measure and observe the film formation behavior when a small amount of lubricating medium is introduced into the water. Additionally, a surface-modified disc is used to examine the impact of wettability gradients on the film-forming capability of the lubricating medium. The results indicate that the film thickness between the roller and the disc increases with the injection of two types of lubricating oils into the water at varying disc speeds, both for the original and modified discs. During the 10-second oil supply period, the spreading behavior of the lubricating oil on the lubricating track influences the film thickness stability. Furthermore, the surface-modified disc demonstrates an enhanced film thickness compared to the original disc, and viscosity becomes a key factor limiting the film-forming capability of the lubricating oil as the disc speed increases for both disc types. This research offers valuable insights for the design of new water-lubricated bearings.