Starved Grease Lubrication of Rolling Contacts

Many grease lubricated roller bearings operate in the starved elastohydrodynamic (EHL) regime where there is a limited supply of lubricant to the contact (1). Under these conditions the film thickness drops to a fraction of the fully flooded value (2) and, thus, it is difficult to predict lubrication performance, or bearing life, from conventional EHL models. In this regime film thickness depends on the ability of the grease to replenish the track rather than the usual EHL considerations. The conventional view of grease lubrication is that base oil bleeds from the bulk reservoir close to the track, replenishing the inlet and forming a fluid EHL film (3). Resupply, under starved conditions, will thus depend on both operating conditions and grease parameters. The aim of this paper is to evaluate the influence of these parameters on starved lubrication in a rolling contact. Starved film thickness has been measured for a series of greases and the results have been compared to the fully flooded values. These s...