Oil-bleeding Dynamic Model to Predict Permeability Characteristics of Lubricating Grease

For grease lubrication, the dominating mechanism supplying new oil to the lubricated contact is assumed to be “oil bleeding” in which the key parameter is the grease permeability. This paper proposes a dynamic oil bleeding model based on a static oil bleeding apparatus. This model uses a permeability correlation that has been adapted to consider the effect of temperature. Grease is described as a porous network of thickener fibres that contains the oil which bleeds out when it is compressed. This system was described by mass and momentum balance equations. The resulting dynamic simulation and the experimental results were compared to obtain the permeability value by using a parametric estimation method. Results are consistent with those found in the literature.