Bearing means to hold up. As the name suggests, the main function of bearing is to use a special structure or material to install on the shaft to reduce the friction when the shaft is running. It also helps to ensure the rotation accuracy of the shaft and at the same time to ensure the shaft's rotation accuracy. Also plays a protective role.

Bearing damage in general is basically inseparable from the following reasons:

1. Material fatigue;

2. Poor lubrication;

3. Pollution;

4. Installation problems;

5. Improper handling;

1. The raceway surface and roller surface are full of dents

The particles on the cage and the raceway surface are worn, and the grease (agent, discoloration) is usually caused by the unclean installation process. Keep it clean during installation, use new grease, and check whether the seal is intact.

2. Wear caused by improper lubrication

The surface wear is mirror-like and the color is blue or brown. This situation is caused by insufficient lubrication. It should be a lubrication condition. Re-determine the lubrication cycle and oil seal.

3. Dents caused by improper installation

Both the inner and outer ring working surfaces have indentations spaced equal to the distance between the rollers. The reason is that the ring is not struck on the correct ring during installation, or the tapered shaft is pushed too far, or the load is overloaded in the static state.

4. Dents caused by foreign objects

The working surface and roller surface are covered with dents, which may be caused by foreign matter brought in during installation or lubricant foreign matter and the surrounding environment. Clean the bearing installation, use clean lubricant and check the oil seal.

5. Scratches on roller end surface

The end face of the roller rubs against the guide rib, causing scratches and discoloration. This condition is caused by slippage under excessive axial load or insufficient lubrication. For this type of damage, a lubricant with higher viscosity can be selected.

6. Wear of rollers and raceways

There is wear and local discoloration on the rollers at the beginning of the raceway load zone. This is caused by the sudden acceleration of the rollers entering the load zone. There are two possible ways; one is to choose a lubricant with higher viscosity; the other is to reduce the bearing clearance.

7. Wear on the outer surface

There are scratches and local discoloration on the inner hole of the inner ring and the outer surface of the outer ring. This situation is caused by relative movement between the ring and the shaft or the bearing box. The only solution is to increase the interference between the ring and the shaft or bearing box to prevent mutual rotation. Axial braking or clamping cannot solve such problems.

8. Surface pits

Small and shallow pit marks on the raceway, rolling element surface or large cross-section are in the form of crystalline damage. This is due to poor lubrication. For example: less oil or viscosity changes caused by temperature rise, the oil film cannot separate the contact surface, and the surface has instant contact.

Required: Improve bearing lubrication. The purpose of bearing lubrication is to reduce internal friction and wear of the bearing, prevent burning, extend fatigue life, discharge friction heat, and cool down. Traditional rolling bearing lubrication methods, such as oil bath lubrication, oil cup lubrication, splash lubrication, circulation lubrication and oil mist lubrication, can no longer meet the lubrication requirements of high-speed spindle bearings. This is because high-speed spindle bearings not only There are strict requirements on the viscosity of the oil, and there are also strict requirements on the amount of oil supplied. In order to obtain the best lubrication effect, too much or too little oil supply is harmful. The oil-air lubrication system can accurately control the amount of lubricating oil at each friction point and is extremely reliable, so it can be used in the field of high-speed spindle bearings.

9. Fretting corrosion

This phenomenon occurs when there is relative movement between the bearing ring and the shaft or bearing box. This is due to a too loose fit or bearing housing deformation.

10. Current corrosion

There are dark brown or gray-black straight streaks or pits on the surface of the rolling or rolling elements. When current passes through the bearing, welding occurs on the surface of the bearing parts.

Solution: Prevent current from flowing through the bearing.

11. Peeling at symmetrical positions on the rolling surface

One of the two rings has obvious signs of stress at a radially symmetrical position, and its skin is peeled off. This is due to bearing box deformation and elliptical compression, so the bearing box must be remade.

12. Spalling caused by axial load

The stress marks are obvious, and the skin on one side of the ring or one of the raceways of the double-row bearing is peeled off.

Reason:

a. Axial load caused by incorrect installation;

b. Pre-pressure transition;

c. The non-fixed bearing is stuck or the axial displacement reserve is insufficient.

13. Peeling caused by impressions

The raceway surface is peeled off and has marks equal to the distance between the rollers. This is caused by incorrect installation and the bearing is overloaded in the static state. Other minor marks may be foreign matter introduced during installation or foreign matter in the lubricant.

14. Cracks caused by rough installation and beating

This crack is a chip that breaks apart and usually only occurs on one side. This is due to the impact force caused by rough knocking transmitted to the end face of the ferrule through the rolling elements. Do not hit the bearing ring directly.

15. Cracks caused by excessive extrusion

Cracks pass through the entire section. This is caused by the interference fit of the inner ring of the bearing being too large or excessive advancement on the tapered shaft.

16. Cracks caused by fretting corrosion

On the inner ring, it is the transverse direction, and on the outer ring, it is the circumferential direction. This is caused by a too loose fit or poor shape of the bearing housing.

17. Peeling caused by fretting corrosion

The raceway surface of the bearing ring is peeling off. There is corrosion relative to the flaking outer surface here. The fit is too loose or the shape of the bearing box is incorrect.

Different bearings have different lifespans, and the factors that affect the lifespan of bearings are:

1. Influence of materials;

In terms of bearing material technology, we mainly ensure the improvement of bearing life through material selection, material guarantee and heat treatment. Rolling bearings are generally made of high-carbon chromium bearing steel, and their chemical composition remains almost unchanged. However, different smelting methods have different purity of materials, which has a great impact on the life. Under the same contact stress conditions, the contact fatigue life of Zhen IV4 ceramic bearings is better than that of bearing steel bearings; under the conditions of high speed, light load and small impact load , ceramic ball bearings can be preferred. It can be seen that the impact of materials on the fatigue life of bearings is very significant.

3. Effect of temperature;

Effect of temperature: Whether it is a fatigue model based on subsurface stress or a model starting from defects on the surface, the impact of heating in the bearing contact area on fatigue life is not considered. In fact, after continuous operation of the bearing, there will inevitably be a certain temperature rise. The magnitude of this temperature rise should be related to the thickness of the lubricating oil film between the contact pairs, the surface characteristics of the contact parts, the load, operating speed and other parameters. . At the same time, when the temperature rises, there must be a temperature distribution in the bearing ring and rolling body, and thermal deformation will occur due to the influence of thermal expansion, affecting the operating accuracy of the bearing. Therefore, the impact of temperature rise and heat on fatigue life cannot be ignored.

4. The influence of lubrication technology;

In terms of bearing lubrication technology, the life of bearings is improved mainly through the selection of lubricants and lubrication methods. Lubrication technology has become one of the most critical factors in improving bearing life. Especially for sealed bearings, grease life has become another "synonym" for bearing service life, that is, grease life is the bearing service life.

5. The impact of operating speed;

Influence of operating speed: Bearing fatigue life is related to instantaneous contact time. The instantaneous contact time refers to the time required for the rolling element to roll over the ring and the width of the ellipse in contact with the ring raceway under maximum load. As the rotational speed increases, the instantaneous contact time increases, and the fatigue life of the bearing decreases. The slower the bearing, the longer its life in revolutions. On the other hand, the length of instantaneous contact time will also affect the surface residual stress, thereby indirectly affecting the fatigue life.

6. Influence of load;

The influence of rolling element parameters and curvature coefficient on the fatigue life of deep groove ball bearings. Research shows that the size of the load has a great influence on the fatigue of the bearing. The fatigue life of rolling bearings depends largely on the maximum rolling element load. Therefore, the increase in load causes the maximum rolling element load to increase significantly and the fatigue life to decrease.