Greases for powertrains: thickener effect, electric conductivity, and life cycle assessment

The paper shows how grease thickener polarity affects performance of the typical powertrain components: gears and rolling element bearings. Greases based on a non-polar polypropylene thickener reduce friction losses (more than 20%) in high-speed deep groove ball bearings and provide a longer service life (more than 2 times) in highly loaded bevel gears, compared to the greases based on polar lithium thickeners. The electrification and sustainability trends have led to additional requirements to be addresses during grease design process: tunable electric conductivity and reduced environment footprint. The grease design challenges caused by the novel requirements and potential solutions are discussed.