Lubrication increases bearing life in most operating environments. The positive effects of lubrication may be summarized as follows:

• A lubricant film reduces friction and wear between the balls and raceways of the bearing, extending fatigue life.
• Dissipates frictional heat and can provide additional cooling if lubricant is circulated.
• Guards against corrosion and may help prevent foreign material from entering the bearing.

In addition to these general benefits, a good lubricant should have the following intrinsic properties:

• Resists change in structure or consistency during prolonged service.
• Resists excessive viscosity changes at temperature extremes.
• Resists leakage, dripping or throw-off from rotating surfaces.
• Compatibility with materials used in bearings, particularly seals and retainers.
• Tolerate some contamination, including moisture, without loss of characteristics.

Other factors that are affected by lubricant choice include:

• Noise level
• Maximum operating speed
• Torque
• Storage time (shelf life)

LUBRICANT TYPES

Grease: Grease lubricant is comprised of a base oil carried in a thickening agent, which delays migration and evaporation of the oil, lengthening its effective operational and shelf life. Additives may also be included in the basic grease formula to improve corrosion resistance, reduce oxidation, and otherwise improve the lubricant performance. Grease lubrication is recommended unless low torque or high speed is essential to the application.

Oil: In general, oil is used as a lubricant where grease is unsuitable, for example, where low torque or high speed are considerations. Typical oils used are the same as those used as the base oils in greases. The operational life of oils is usually much less than that of equivalent greases due to evaporative losses. One exception is the perfluorinated hydrocarbon family of oils that have extremely low saturated vapor pressure (SVP), giving greatly extended life.