LUBRICATION
| PURPOSE OF
LUBRICATION |
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: |
| 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. |
|
