Bearing Types and Proper Viscosity of Lubricating Oils
The lubricating oils used for rolling bearings are usually highly refined mineral or synthetic oils that have a high oil film strength and superior oxidation and corrosion resistance. When selecting a lubricating oil, the viscosity at the operating conditions is important. If the viscosity is too low, a proper oil film is not formed and abnormal wear and seizure may occur. On the other hand, if the viscosity is too high, excessive viscous resistance may cause heating or large power loss. In general, low viscosity oils should be used at high speed; however, the viscosity should increase with increasing bearing load and size.
The following table gives generally recommended viscosities for bearings under normal operating conditions.
| Bearing Type |
Proper Viscosity
at Operating
Temperature |
Ball Bearings and
Cylindrical Roller Bearings |
Higher than 13mm 2 /s |
Tapered Roller Bearings and
Spherical Roller Bearings |
Higher than 20mm 2 /s |
| Spherical Thrust Roller Bearings |
Higher than 32mm 2 /s |
Remarks: 1mm 2 /s=1cSt (centistokes)
|
