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How To Choose Right Bearing Grease

Source:  skf bearing  Time:  2021-02-16

Rolling bearings are widely used in industrial production and are the basic accessory parts of mechanical equipment. The function of the rolling bearing is to convert the sliding friction between the shaft and the shaft seat into rolling friction. During the operation of the rolling bearing, the rolling friction will cause the bearing to heat up and wear. In order to reduce friction and damage, the rolling bearing needs to be lubricated during operation.


What lubrication method can be used for rolling bearings


1. Grease lubrication


2. Oil lubrication 


Grease lubrication of rolling bearings


Rolling bearings use grease as the lubricating medium. Its advantages are that the grease has low fluidity, is not easy to leak, and the formed oil film has good strength, which is more conducive to the sealing use of rolling bearings. At the same time, the use of grease lubrication for rolling bearings can extend the lubrication maintenance time, making bearing maintenance easier.Rolling bearing lubrication with grease also has disadvantages. Compared with lubricating oil, grease has a larger frictional torque and is less suitable for rolling bearings that require high-speed operation. In addition, the grease lubrication method has poor cooling performance. If too much grease is added to the rolling bearing, the rolling bearing will overheat due to the stirring of the lubricant.

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Oil lubrication of rolling bearings


Rolling bearings are lubricated by oil lubrication, which can achieve good cooling and cooling effects, and is especially suitable for rolling bearings with relatively high operating temperatures. The viscosity of the lubricating oil used in rolling bearings is about 0.12 to 0.2cm/s. If the load of the rolling bearing is high and the working temperature is high, the high viscosity lubricating oil should be selected, and the rolling bearing with fast speed is suitable for the low viscosity lubricating oil.The disadvantage of using oil lubrication for rolling bearings is that oil lubrication requires the bearing to maintain a good sealing condition to avoid lubricating oil leakage. In addition, oil lubrication requires a more complicated oil supply device, which is not as convenient as grease in operation and use, which increases the maintenance workload of rolling bearings.


The purpose of bearing lubrication: The purpose of the lubrication of rolling bearings is to reduce the internal friction and wear of the bearing, prevent burning, and its lubrication effect is as follows.


(1) Reduce friction and wear.


In the mutual contact part of the ring, rolling element and cage constituting the bearing, metal contact is prevented, and friction and wear are reduced. 


(2) Extend fatigue life.


The rolling fatigue life of the bearing is prolonged if the rolling contact surface is well lubricated during rotation. On the contrary, if the oil viscosity is low, the thickness of the lubricating oil film is not good, and it is shortened. 


(3) Discharge the frictional heat and cool down.  


The circulating oil method can use oil to dissipate heat generated by friction or heat transferred from the outside and cool. Prevent the bearing from overheating and prevent the lubricant from aging. 


(4) Other


It also has the effect of preventing foreign matter from intruding into the bearing, or preventing rust and corrosion. 


Lubrication method:


Bearing lubrication methods are divided into grease lubrication and oil lubrication. In order to make the bearing function well, first of all, it is necessary to select a lubrication method suitable for the use conditions and purpose. If only lubrication is considered, the lubricity of oil lubrication is dominant. However, grease lubrication has the advantage of simplifying the structure around the bearing. The advantages and disadvantages of grease lubrication and oil lubrication are compared.