NSK bearings have both rolling and sliding friction. Sliding friction is caused by the deviation of the rolling bearing on the surface curve and the deformation of the bearing under load. For example, between the rolling element and the ring, since the ball and the ring are not absolute rigid bodies, their contact area must always be elastically deformed, in theory, it is point contact or line contact, but in fact, the load working condition must always become surface contact Therefore, the contact points with different diameters have different linear velocities to produce sliding friction. For various reasons, the sliding friction between the rolling element and the cage, as well as between the cage and the inner and outer rings, can also occur. NSK 23024 CDKE4S11 bearings online , pls click here :
The sliding friction increases with the increase of speed and load. In order to reduce friction, wear, reduce temperature and noise, and prevent bearing components from rusting, the correct selection of lubricants and reasonable lubrication methods are used to properly control the amount of lubricants. It is an important issue to improve the life of NSK bearings.
1. Basis for oil or grease used in NSK rolling bearings :
The advantages of using lubricating oil for rolling bearings are:
(1) Under certain operating specifications, the starting torque and friction loss of lubricating oil is significantly smaller than that of grease lubrication.
(2) Since the lubricating oil takes away heat in the circulation and plays a cooling role, the bearing can achieve a relatively high rotation speed.
(3) It can guarantee a relatively high use temperature.
(4) When changing the grease, the related connecting parts must be disassembled, and there is no such trouble when lubricating with oil.
(5) It is very suitable when the bearings in the reduction gearbox are lubricated with lubricating oil, because the oil simultaneously achieves the purpose of lubricating gears and bearings at the same time in a splashing manner.
(6) The grease in the bearing is gradually contaminated by products that are worn by the product, abrasives, products that penetrate through the sealing device from the outside, and products that are aging themselves. If not replaced in time, it will cause accelerated wear of the bearing, and when applying a liquid lubricant, It can be filtered to ensure its normal operation.
The advantages of grease lubrication for NSK rolling bearings:
(1) Individual bearing points must be lubricated frequently by hand. If the grease is replaced, 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 simplify the design.
(3) Experience has shown that within a certain speed range (n<20000r/min or dn<20000mm.r/min), lubricating with lithium-based grease has a lower temperature rise and longer bearing life than using the oil-drop method.
2. NSK rolling bearing lubrication theoretical basis
The lubrication mechanism of rolling bearings belongs to the theory of elastic fluid dynamic pressure lubrication.
3. The relationship between NSK rolling bearing failure types and lubrication
When choosing a grease, you must choose a grease that is compatible with the conditions of use (temperature, speed, load, environment, etc.). These are related to the basic characteristics of the grease, and the basic characteristics of the grease depend on the thickener and the base oil kind of.