Prediction of bleeding behavior and film thickness evolution in grease lubricated rolling contacts

Abstract

While a rolling element bearing is operating, the lubricating film is desired to maintain a sufficient thickness to avoid asperity contact between surfaces. When using grease as lubricant, the film thickness undergoes evolution over time, due to the transient formation of the deposited thickener-rich layer and a bled oil film. Therefore, a model, which can address both type of film formation, is required. In this contribution, an experimentally validated numerical model is proposed by assuming the grease as a porous medium. This model can calculate the transient formation of thickener-rich layer and the oil bleeding process for grease-lubricated contacts. The predicted film thickness evolution, by superposing the thickener-rich layer and oil film, shows a reasonable agreement with the experimental result.