Purposes and methods of the Bearing Lubrication

Purposes of Lubrication

The main purposes of lubrication are to reduce friction and wear inside the bearings that may cause premature bearing failure. The effects of lubrication may be explained briefly as follows:

Reduction of Friction and Wear
Direct metallic contact between the bearing rings, rolling elements and cage, which are the basic components of a bearing, is prevented by an oil film which reduces the friction and wear at the contact areas.

Extension of Fatigue Life
The rolling fatigue life of bearings depends greatly upon the viscosity and film thickness as the rolling contact surfaces. Generally, a heavier film thickness prolongs the fatigue life.

Cooling
Circulating lubrication may be used to carry away frictional heat or heat transferred from the outside to prevent the bearing from overheating and the oil from deteriorating.

Others
Adequate lubrication also helps to prevent foreign material from entering the bearings and guards against corrosion or rusting.

The various lubricating methods are divided into grease and oil lubrications. Satisfactory bearing performance can best be achieved by adopting a lubricating method that is most suitable for a particular application and operating condition. Oil lubrication is superior in lubricating efficiency, however, grease lubrication allows a simpler structure around the bearings.
Lubricating Methods

Grease lubrication
Sealed (RS, 2RS) or shield (ZZ, Z) bearings are generally factory-packed with the proper amount of good quality grease and can be used as delivered.
More than the normal amount of grease can cause heat generation or grease leakage.
Generally, SNH fills less than half of the free internal space inside bearings.
Since the brand of grease affects bearing performance, SNH usually recommends a suitable grease according to applications. For assistance when selecting grease, you may consult SNH.

Oil lubrication
Oil lubrication is used when it is difficult to achieve satisfactory performance by using grease lubrication, for example, when an extremely low torque or a high-speed operation is required.
Particularly in the case of gyro-gimbals and synchros that are largely affected by frictional torque, low viscosity oil is used. Oil mist or oil lubrication provides low heating due to agitation and also superior cooling of the bearing.

Linqing Nine Star Bearing Science & Technology Co., Ltd 

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