An Evaporation Model for Base Oil from Grease-Lubricated Rolling Bearings including Breathing

The film thickness decay of grease-lubricated bearings is determined by a loss of lubricant from the bearing. One of these loss mechanisms is base oil evaporation. In this article, a model is presented for evaporation where the volatiles leave the bearing by breathing. The model is applied to a typical drive cycle where the temperature is varied in time. The impact of the volatility of base oils and quality of sealing on the evaporation losses can be quantified with this model.