Lubrication
The correct choice of lubricant and method of lubrication is as important for the proper operation of the bearing as the selection of the bearing and the design of the associated components.
Grease lubrication
Grease should be used if…
- Maintenance-free operation over long periods of time is desired,
- the maximum speed of the bearing does not exceed the speed factor n x dm of the grease,
- the heat generated is almost uniformly dissipated by the environment,
- low friction losses are required with bearings working under small loads and at high speeds.
Running-in period with grease lubrication
In order to obtain an optimum lubrication effect and grease life it is advisable to provide for a running-in period for bearings for high-speed applications. A better grease distribution and, at the same time, a low bearing temperature are thus achieved.
Grease manufacturer offer a multitude of greases suitable for high speeds. The n x dm factor is a criterion for the selection of the grease taking into consideration bearing size and operating speed.
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| D: Bearing outside diameter [ mm] d: Bearing bore diameter [mm] |
| n: Bearing operating Speed [1/min] |
Oil lubrication
Oil lubrication should be provided if…
- High speeds do not permit the use of greases,
- the lubricant must simultaneously serve to cool the bearing.
The most widely used lubricating methods are:
- Oil mist lubrication:The oil mist is produced in an atomizer and conveyed to the bearings by an air current.
The air current also serves to cool the bearings and the slightly higher pressure prevents contamination from penetration. - Oil-air lubrication (total loss lubrication):The oil is conveyed to the bearing in droplets by compressed air. The droplet size and the intervals between two droplets are controlled.
- Oil-jet lubrication (cooling lubrication):Considerable amounts of oil are carried through the bearing by injection, the frictional heat generated in the bearing is dissipated. The cooling of the oil is achieved e.g. with an oil-to-air heat exchanger.
