Effect of Grease Filling on the Film Thickness in Deep-Groove Ball Bearings

Abstract

Determining the film thickness during the bleeding phase of grease lubrication in a bearing is difficult due to the various replenishment and loss mechanisms involved. An additional factor that could influence the film thickness is the amount of grease in the bearing. In this study, film thickness is measured in deep-groove ball bearings using two different greases, each with initial grease filling percentages of 7.5%, 15%, and 30% of the bearing’s free volume. Film thickness is measured during the early stage of the bleeding phase at various loads and speeds using the electrical capacitance method. Results show that, after churning, values of temperature and film thickness are similar for the three different filling quantities. This indicates that bulk grease flow or oil bleed from the reservoirs formed in the unswept region does not impact the lubricant film thickness in the early stage of bearing operation.

Keywords:

• Rolling bearings
• grease
• film thickness
• oil bleeding
• grease filling

Disclosure statement

No potential conflict of interest was reported by the author(s).

Acknowledgments

We thank Min Gao for performing some of the experiments. We also thank SKF Research and Technology Development and Shell for funding this work and for their approval to publish this article.