Fundamental Properties of a Good Bearing Grease

Fundamental Properties of a Good Bearing Grease

Grease for Lubrication

Grease is a dispersion of thickening agents in a base oil. The oil component typically influences the temperature stability of the compound, whereas thickeners are added to give the grease special properties like electrical conductivity and thermal conductivity. A lubricating grease such as white lithium grease works by lowering the coefficient of friction at the interface between 2 or more parts. It is often used as a gear grease and to protect bearings.

Figure 1: Schematic depiction showing how to apply lubricating grease to ball bearings
Figure 1: Schematic depiction showing how to apply lubricating grease to ball bearings

White Lithium Grease Uses

Lithium grease is used primarily as a lubricant to reduce wear and extend the parts’ life by reducing friction, which reduces mechanical wear and heat buildup. It can be used as a pulley bearing grease, or you can use white lithium grease for door hinges. This low friction grease has a soft, smooth texture characterized by a low NLGI consistency number determined by measuring the worked penetration range.     

Figure 2: Comparison of a hard grease (left) with a soft grease (right) based on worked penetration
Figure 2: Comparison of a hard grease (left) with a soft grease (right) based on worked penetration

Is Lithium Grease Electrically Conductive?

Lithium grease is considered an electrical insulator, meaning it will not carry an electrical charge. It is important to consider this when applying the grease as it must not be applied along any electrical path since it would halt the current flow, rendering the device inoperable. This point is irrelevant in the case of a bearing since bearings do not carry electrical current.

Is Lithium Grease Waterproof?

Lithium grease is hydrophobic and repels water, preventing corrosion and water washout. This makes it an ideal lubricant in outdoor environments, including marine applications.