Impact of grease churning on grease leakage, oil bleeding and grease rheology

Abstract

Grease performance is strongly determined by the properties and quantity of the grease after the churning phase in which grease reservoirs are formed. During this churning phase, macroscopic flow takes place, leading to drag forces dissipating energy in the grease, generating heat and causing thermo-mechanical degradation. The impact of grease churning on grease properties such as oil bleed, leakage and rheology was studied using bearing experiments and a roll stability tester. Grease leakage increased whereas oil bleeding capacity and tackiness decreased with increased churning intensity, measured as temperature-corrected energy density.