Experimental study of lubricant distribution and lubrication enhancement induced by ball bearing cage

Abstract The bearing cage played a pivotal role in affecting the lubricant redistribution and lubrication states. To facilitate a quantitative study of cage-induced lubrication phenomena, an optical ball-on-disc apparatus is enhanced with a cage unit, and the interaction between the rolling element and the cage is simulated. After that, the oil reservoirs surrounding the contact area and the film thickness were measured. The results showed that the lubricant reservoirs and inlet lubricant supplement were significantly improved with the employment of the cages. Besides, the lubricating state transformed from starved lubrication to fully flooded condition. Consequently, the lubrication states are effectively enhanced. The lubricant on the steel ball surface moved from the side bands to the central rolling track, which meant that the lubricant redistribution was the main reason for the lubricating enhancement. Notably, the groove modification on the inner surface of the cage pocket facilitated the directional lubricant migration, and the migration effect depended on the groove angles. These results help to understand the bearing lubrication mechanism, thereby inspiring advancements in cage design and lubricant flow regulation.