This work focused on the experimental study of grease lubrication mechanisms around contacts in radial ball bearing 6314. The main objective of this work was to show the influence of conformities and their impact on grease lubrication in ball bearings. For the experiments, a tribometer of ball-on-ring configuration was used and fluorescence microscopy was chosen as the observation method. The results showed that, under starvation conditions, a conformity of 0.52 at velocities around 2 m/s produces a 50% thicker lubricating film than a conformity of 0.58. The available amount of lubricant around the contact area for conformity 0.52 was approximately three times less than that for conformity 0.58, and the same ratio was observed for the amount of lubricant on the rolling track. Experiments show that a realistic tribometer geometry allows a more accurate experimental study of the lubrication mechanisms of greases in ball bearings.

Grease is important lubricant for ball bearings as it is used much more often than oil. However, mechanism of the lubrication is not completely clear, especially concerning the role of the thickener in the lubricating process. It was shown that contribution of the thickener to film thickness build-up varies with operating conditions. Also, its influence on the resistive torque of the bearing was proved. However, all studies were in-direct showing its effects. This paper presents new in-situ fluorescence method of the grease constituents' observation, where both, thickener, and base oil can be observed independently. Two different fluorescence dyes are used to distinguish grease constituents with the use of different microscope setup. Moreover, the new method was tested on two different test rigs. First is typical ball on disc test rig widely used for study of elastohydrodynamic lubrication. Second is ball on ring test rig which more closely represents radial ball bearing conditions. It was shown that thickener engagement is very different for each geometrical configuration.

Grease is important lubricant for ball bearings as it is used much more often than oil. However, mechanism of the lubrication is not completely clear, especially concerning the role of the thickener in the lubricating process. It was shown that contribution of the thickener to film thickness build-up varies with operating conditions. Also, its influence on the resistive torque of the bearing was proved. However, all studies were in-direct showing its effects. This paper presents new in-situ fluorescence method of the grease constituents’ observation, where both, thickener, and base oil can be observed independently. Two different fluorescence dyes are used to distinguish grease constituents with the use of different microscope setup. Moreover, the new method was tested on two different test rigs. First is typical ball on disc test rig widely used for study of elastohydrodynamic lubrication. Second is ball on ring test rig which more closely represents radial ball bearing conditions. It was shown that thickener engagement is very different for each geometrical configuration.