Mechanisms of grease lubrication in rolling element bearings

Most rolling element bearings is use today are grease lubricated. Grease is chosen for a variety of reasons as it gives low friction, is easily confined and has a long lubricating life at low cost. In many applications the grease is expected to lubricate effectively over a wide range of conditions and for extended periods. For such applications lubricant failure leads to instantaneous and rapidly increasing damage of the components and eventually failure. Despite the overwhelming importance of this subject very little is known about the mechanisms of grease lubrication and the relationship between composition, lubrication performance and life. This paper, therefore, attempts to summarise our current understanding of grease lubrication mechanisms in rolling element bearings.