27 reasons why TN bearings are ringing

After a long-term summary by the technicians, there are 27 reasons for the NTN bearing to sound. There may be many that we have not encountered before, and will be slowly replenished later.

1. The NTN bearing is mixed with impurities such as sand or carbon particles to act as an abrasive.

2. The NTN bearing is mixed with moisture, acid or paint and other dirt, which acts as a corrosive effect;

3. The clearance of the NTN bearing is too small (the selection is not appropriate);

4. The lubricating oil or grease type is incorrectly selected;

5. Insufficient lubrication (oil level is too low, oil or grease leaks through the seal);

6. The NTN bearing is flattened by the seat hole (the roundness of the seat hole is not good, or the seat hole is not twisted straight);

7. The horn of the bottom surface of the NTN bearing housing is not flat (resulting in deformation of the seat hole or even cracking of the NTN bearing housing);

8. There are debris in the hole of the NTN bearing housing (residual chips, dust particles, etc.);

9. The seal is eccentric (wearing adjacent parts and rubbing);

10. NTN bearings are subjected to additional loads (NTN bearings are axially tightened, or two fixed-end NTN bearings on one shaft);

11. The thermal elongation of the shaft is too large (NTN bearing is subjected to static and indeterminate axial additional load);

12. The clearance of the NTN bearing is too small, and the rotation is too tight (the tightening sleeve is too tight);

13. NTN bearing is noisy (caused by the end face of the roller or the ball is slipping);

14. The fit between the NTN bearing and the shaft is too loose (the diameter of the shaft is too small or the adapter sleeve is not tightened);

15. The shoulder is too large (touching the seal of the NTN bearing and rubbing);

16. The shoulder of the seat hole is too large (the seal of the NTN bearing is distorted);

17. The gap of the labyrinth seal is too small (friction with the shaft);

18. The teeth of the lock washer are bent (touching the NTN bearing and rubbing);

19. The position of the oil ring is not suitable (the flange cover is encountered and friction occurs);

20. There is a pressure pit on the steel ball or roller (caused by hammering NTN bearing when installing);

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Analysis: The form of early bearing damage

This natural damage is unavoidable during normal use of the bearing due to wear and tear until it eventually loses its ability to work and ends its service life. However, if the bearing is prematurely worn or damaged due to improper adjustment of the engine assembly, poor quality of the lubricating oil or poor use conditions, it is an early damage caused by man.

Early damage not only greatly reduces the service life of the bearing, but also affects the normal operation of the engine. According to the long-term experience of diesel engine maintenance, the common forms of early damage of sliding bearings are mechanical damage, bearing cavitation, fatigue pitting, corrosion and so on.

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Internal structure of NSK bearings

NSK bearing internal structure

A - Bearings with different internal design and standard.

A——Angle contact ball bearing with a contact angle of 30 degrees.

A5 - angular contact ball bearing, contact angle is 25 degrees.

B——Angle contact ball bearing with a contact angle of 40 degrees.

C——Angle contact ball bearing with a contact angle of 15 degrees.

C——Tapered roller bearing with a contact angle of 20 degrees.

D - Tapered roller bearing with a contact angle of 28 degrees.

C, CA (with brass solid cage), CD (with stamped cage) - high load spherical roller bearings.

E - High load cylindrical roller bearing.

H——High load thrust spherical roller bearing.

J——The small end diameter, angle and outer ring width of the outer ring raceway of tapered roller bearing are consistent with ISO regulations.

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Lubrication tips for Swedish SKF bearings

Rust prevention performance

The grease used in the bearing must have an anti-rust effect, and the anti-rust agent is preferably insoluble in water. Grease should have good adhesion to form an oil film on the surface of the steel, even if the grease is filled with water.

Mechanical stability

Grease becomes soft during machining and causes leakage. When there is a vibration application example, grease will be trapped inside the bearing by the bearing housing. If the mechanical stability of the grease is insufficient, the grease will be continuously thrown out of the bearing, which will cause mechanical collapse of the soap structure and destruction of the grease.

Oil seal

Oil seals are necessary to protect bearings and lubricants from external contamination, and no matter whether debris or moisture can penetrate into the bearings to prevent damage. Proper installation and maintenance is an important factor in the longest service life of the bearing. At the same time, attention must be paid to the cleanliness of the bearings, the correctness of the choice of bearings and the selection of appropriate installation and maintenance tools. Bearings must be protected from contaminants and moisture and must be properly installed and lubricated. The design of the bearing arrangement, the condition of the oil seal, the type of lubricant and the lubrication cycle, as well as the special maintenance play an important role.

Mixed grease

Never mix incompatible greases. If two incompatible greases are mixed, the consistency will usually soften and eventually damage may occur due to the loss of grease. If you don't know which type of grease the bearing originally used, you should first remove the old grease inside and outside the bearing to add grease.

Classification of oils and fats

According to temperature and working conditions: grease can be classified according to their allowable working temperature. The consistency and lubricating ability of grease are affected by working temperature. Bearings operating at a certain temperature must choose the correct consistency and good at the same temperature. Lubricating grease. Grease is manufactured in different operating temperature ranges and can be classified into low temperature (LT), medium temperature (MT) and high temperature (HT) greases. At the same time, there is a type of grease called EP (extrusion resistant) or EM (resistant to extrusion and added molybdenum disulfide), with additives to enhance the strength of the lubricant film.

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What are the ways to control the influence of bearing noise?

Generally speaking, in order to control the noise influence of the rolling bearing, it is necessary to take countermeasures against the root cause of these noises in order to receive the effect of the root cause. The main route is:

(1) Select low noise bearings;

(2) Try to eliminate noise from the application of the bearing,

(3) Avoid resonance with the host and avoid resonance sensitive speed;

(4) When other methods are ineffective, take additional measures for sound insulation and noise reduction.

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FAG bearing damage and countermeasures?

FAG bearing maintenance, overhaul, and abnormal handling
In order to maintain the original performance of the bearing in a good condition for as long as possible, it is necessary to maintain, repair, and prevent accidents, ensure the reliability of operation, and improve productivity and economy. Maintenance is best carried out on a regular basis in accordance with the operating standards for the mechanical operating conditions. The contents include monitoring of operating conditions, replenishment or replacement of lubricants, and inspections for periodic disassembly.

FAG bearing damage and countermeasures

In general, if the bearing is used correctly, it can be used until the fatigue life is reached. However, there will be accidents that are prematurely damaged and cannot be used. This early damage, as opposed to fatigue life, limits the quality of what is called a fault or accident. Many of them are caused by inadvertent installation, use, and lubrication, and foreign objects intruding from the outside are insufficiently studied for the thermal effects of the shaft and the outer casing.

Regarding the damage state of the FAG bearing, for example, the jam of the ferrule of the roller bearing, as a cause, the lubricant is insufficient, unsuitable, the defect of the oil supply structure, the foreign matter intrusion, the bearing installation error, the shaft deflection If the song is too big, there will be coincidences of these reasons.

Therefore, it is difficult to know the true cause of the damage by only investigating the bearing damage. However, if you know the mechanical use of the bearing, the conditions of use, the structure around the bearing, and the situation before and after the accident, combined with the damage state of the bearing and several reasons, it can prevent similar accidents from happening again.

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Detailed explanation: spherical bearing with seat

Insert bearing with housing bearing type bearing angular contact bearing: ball and ferrule nominal contact angle greater than 0 °, and less than 90 ° rolling bearing. It can withstand both radial and axial loads. Can work at higher speeds. The larger the contact angle, the higher the axial load carrying capacity. High precision and high speed bearings typically take a 15 degree contact angle. Under the axial force, the contact angle will increase.

2, with the spherical bearing type:

1), with a set screw outer spherical surface UC type bearing;
2), with a tapered hole outer spherical surface UK bearing;

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