The process of churning in a grease lubricated rolling bearing: Channeling and clearing

The grease lubrication process can be divided into a “churning” and “bleed” phase. In this paper it will be shown that the churning phase consists of two other phases: a “channeling” and “clearing” phase. During channeling, by far most of the grease is pushed sideways, making a “grease channel”. This happens very quickly. During the clearing phase, churning continues but now with only a small and constant volume of grease. The transition from the clearing to the bleed phase is characterized by a sudden decrease of grease volume in the running track. The end of the churning phase and therefore of the clearing process is determined by a critical energy.