Control of the amount of grease used in NTN bearings

NTN bearing lubrication is indispensable, so everything is done. How to master the amount of NTN bearing lubrication is very useful for NTN bearing maintenance. We know that grease has good adhesion, wear resistance, temperature resistance, rust resistance and lubricity. It can improve high temperature oxidation resistance, delay aging, dissolve carbon deposits, and prevent metal debris and oil stains from agglomerating. Improve the wear resistance, pressure resistance and corrosion resistance of the machine.

After understanding the movement of the grease in the NTN bearing, it is natural to conclude that the grease in the NTN bearing should not be excessive. More grease is not only wasted, but also harmful. The higher the speed of the NTN bearing, the greater the hazard.
The more grease is filled, the greater the friction torque. With the same amount of filling, the friction torque of the sealed NTN bearing is greater than that of the open NTN bearing. After the grease filling amount is equivalent to 60% of the internal space volume of the NTN bearing, the friction torque is no longer significantly increased. This is because most of the grease in the open NTN bearing has been extruded, and the grease in the sealed NTN bearing has also been lost.

As the grease filling amount increases, the temperature rise of the NTN bearing increases linearly. The same filling amount, the temperature rise of the sealed NTN bearing is higher than that of the open NTN bearing.

It is generally believed that the grease filling amount of the sealed rolling NTN bearing should not exceed 50% of the internal space. Tests by Shawki and Mokhtar have shown that ball NTN bearings are most suitable from 20% to 30%.

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SKF imported bearings with good grease or oil choice

Imported bearings have both friction and sliding friction. Sliding friction is caused by the deviation of the inlet bearing on the surface curve and the deformation of the inlet bearing under load. For example, between the body and the ring, since the ball and the ring are not absolutely rigid bodies, their contact areas always have elastic deformation, which is theoretically point contact or line contact, but in fact the working conditions under load always become surface contact. Therefore, contact points having different diameters have different linear velocities to generate sliding friction. Sliding friction is also created between the body and the retainer as well as the retainer and the inner and outer rings for a variety of different reasons. The sliding friction increases with the increase of speed and load. In order to reduce friction, wear, reduce temperature and noise, prevent the rust of the components of the imported bearings, properly select the lubricant and use reasonable lubrication to properly control the lubricant. Quantity is an important issue to improve the life of imported bearings.

1. The basis of imported bearings for oil or grease:

The advantages of using imported lubricants for imported bearings are:

1) Under certain operating specifications, the starting torque and friction loss of lubricating oil is significantly smaller than that of lubricating grease.

2) Since the lubricating oil takes away the heat in the circulation to cool, the imported bearing can reach a relatively high rotational speed.

3) It can guarantee a relatively high operating temperature.

4) When changing the grease, the relevant connecting parts must be disassembled, and when it is lubricated with oil, there is no such trouble.

5) When the inlet bearing in the reduction gearbox is lubricated with lubricating oil, it is suitable because the oil simultaneously achieves the purpose of lubricating the gear and the imported bearing at the same time.

6) In the imported bearings, the grease is gradually contaminated by the products worn by the product, the abrasives, the products penetrated from the outside through the sealing device and the products that are aging by themselves. If not replaced in time, the imported bearings are accelerated and worn, and when the liquid lubricant is applied It can be filtered to ensure its normal operation.

Advantages of grease lubrication for imported bearings:

1) Individual imported bearing points must be refueled by hand. If the grease is used, it will save trouble and avoid accidents caused by lack of oil.

2) The grease itself has a sealing effect, which allows the use of a mechanism with a low degree of sealing to achieve a simplified design.

3) It has been proved that the lubrication with lithium grease in a certain speed range (n<20000r/min or dn<20000mm.r/min) has lower temperature rise and longer bearing life than the oil drop method.

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