Rolling bearing lubrication
Rolling bearings are used in many different machines. They are installed in clockworks, rolling mills, industrial plants, bicycles, cars or ships. Rolling bearings enable the transmission of power between moving parts with the aid of rolling elements. In this process, a journal or steel ring rolls on balls, rollers or needles. Subcategories of rolling bearings include ball bearings, roller bearings, and needle bearings.
Lubrication of the rolling bearings is intended to prevent or mitigate contact between the rolling and sliding surfaces. This keeps friction, wear and corrosion to a minimum. In addition, the lubricant in the rolling bearing ensures the removal of dirt and heat. At the same time, the system is sealed against environmental influences.
How are rolling bearings lubricated?
Rolling bearings can generally be lubricated with oils, greases or, in exceptional cases, with solid lubricants. The majority of rolling bearings are supplied with greases, since the design effort required to seal the bearing position is low and the grease rarely or never has to be changed for the complete life of the rolling bearing. However, the specific lubricant required by rolling bearings is determined by the operating conditions and environmental influences. Variables such as material, kinematics, geometry, load direction, rotational speed, running behaviour, temperature, vibrations or dirt ingress must be taken into account.
Each lubricant offers certain advantages and disadvantages in use. We have summarised these for oil and grease for you.
| Advantages | Disadvantages | |
|---|---|---|
| Grease |
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| Oil |
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The ADDINOL high-performance lubricants extend the bearing life of your rolling bearing, increase the operating reliability, reduce the noise level and increase the efficiency. Our application technology will be pleased to advise you.
Which oil is suitable for rolling bearings?
Alloyed or unalloyed mineral oils or synthetic oils can be used for rolling bearings. Mineral oils are used more frequently. Synthetic oils are only required for very high temperature ranges. The viscosity of the oil must be precisely matched to the specific area of application.
Greases for rolling bearings
The correct grease selection is particularly decisive for bearings with higher sliding contents and for large bearings as well as bearings subjected to high loads. At high loads, the lubricity of the thickener and the additives are of particular importance. In general, very little lubricant takes part in the lubrication process. Most of the grease is displaced from the rolling contact and is deposited laterally or leaves the bearing arrangement via the seal. The grease that remains on the running surfaces and laterally in or on the bearing releases the required quantity of oil and thickener for lubrication of the functional surfaces.
For most rolling bearings, greases of class NLGI 2 are suitable. The use of greases of classes NLGI 1 and NLGI 3 is also possible and depends on the application. As with the general selection of lubricants for rolling bearings, operating and environmental conditions must be taken into account. The base oil viscosity and the oil separation are decisive in the selection of the grease.
| Environmental conditions | Properties of the grease |
|---|---|
| Low friction | NLGI 1 or 2, low viscosity synthetic oil |
| Low running noise | NLGI 1 or 2 with high viscosity base oil |
| Bearing axis angular or vertical | NLGI class 2 or 3 adhesive grease |
| Outer ring rotates, inner ring stands still | NLGI 3 or 4 with high thickener content |
| Lifelong lubrication | Class 2 or 3 grease stable to flexing |
| High temperature | Grease without residues |
| Low temperature | Class 1 or 2 grease, synthetic oil if necessary |
| Dusty environment0 | NLGI 3 |
| Condensation water in the process | Emulsifying grease |
| Splash water in the process | Water-repellent grease |
| Aggressive media | Grease with corrosion protection additives |
| Vibrations and shocks | EP grease NLGI 2 |
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