01 Causes of bearing noise

1. Excitation due to the change of the number of loaded rolling elements

When a radial load is loaded on a bearing, the number of rolling elements carrying the load will change slightly during operation, causing the deviation of the load direction.

2. Local damage

A small number of bearing raceways and rolling elements may be damaged due to incorrect operation or installation. During operation, damaged bearing components will produce specific vibration frequencies. Vibration frequency analysis can identify damaged bearing components. This principle has been applied to condition monitoring equipment to monitor bearing damage.

3. Accuracy of relevant parts

When the inner and outer rings of the bearing are closely matched with the bearing seat or transmission shaft, the inner and outer rings of the bearing may be deformed due to improper matching with the shape of adjacent components. If deformation occurs, vibration and noise may occur during operation.

4. Pollutants

If the equipment is operated in a polluted environment, the magazine may enter the bearing rolling element, causing vibration sound. In this case, a disturbing noise can usually be heard.

5. Others

The noise of rolling bearings is caused by complex reasons. One is the wear of the mating surfaces of the inner and outer rings of the bearings. Because of this wear, the matching relationship between the bearing and the housing, and between the bearing and the shaft is destroyed, which causes the axis to deviate from the correct position. The shaft makes abnormal noise when moving at high speed. In addition, the insufficient lubrication of the bearing, the formation of dry friction, and the crushing of the bearing will produce abnormal noise. The bearing is worn and the cage is loose and damaged, which will also produce abnormal noise.

02 Different bearing noise?

1. The noise of ball bearing is lower than that of roller bearing, and the (friction) noise of bearing with relatively less sliding is lower than that of bearing with relatively more sliding; If the number of balls is large and the outer ring is thick, the noise is small;

2. The noise of bearing with solid cage is relatively lower than that of bearing with pressed cage;

3. The noise of the bearing with plastic cage is lower than that of the bearing with the above two cages;

4. The noise of bearings with high accuracy, especially those with higher rolling element accuracy, is relatively less than that of bearings with low accuracy;

5. The noise of small bearing is smaller than that of large bearing.

Different bearings have different noise levels?

1. The noise of ball bearing is lower than that of roller bearing, and the (friction) noise of bearing with relatively less sliding is lower than that of bearing with relatively more sliding; If the number of balls is large and the outer ring is thick, the noise is small;

2. The noise of bearing with solid cage is relatively lower than that of bearing with pressed cage;

3. The noise of the bearing with plastic cage is lower than that of the bearing with the above two cages;

4. The noise of bearings with high accuracy, especially those with higher rolling element accuracy, is relatively less than that of bearings with low accuracy;

5. The noise of small bearing is smaller than that of large bearing.

03. Bearing sounding

1. The grease has impurities;

2. The cage is broken;

3. The bearing raceway is rusted;

4. The bearing is noisy (interfered by external vibration source);

5. The ring raceway is unqualified (manufacturer problem);

6. The bearing clearance is too small or too large (manufacturer problem);

7. The diameter of the seat hole is too small (causing high bearing temperature);

8. Eccentricity of sealing ring (touching adjacent parts and causing friction);

9. There are sundries in the bearing seat hole (residual chips, dust particles, etc.);

10. The bearing has noise (caused by roller end face or steel ball slipping);

11. The shaft shoulder is too large (touching the seal of the bearing and causing friction);

12. The clearance of labyrinth seal ring is too small (friction with shaft);

13. The tooth of the lock washer is bent (it touches the bearing and rubs);

14. The shoulder of the seat hole is too large (distorts the seal on the bearing);

15. The position of the oil slinger is inappropriate (it touches the flange cover and rubs);

16. Impurities such as sand or carbon particles are mixed in the bearing to play the role of abrasive;

17. Steel ball and raceway wear (unqualified grinding or product bruise);

18. The thermal elongation of the shaft is too large (the shaft bears the static indeterminate axial additional load);

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

20. Dirt such as water, acid or paint is mixed in the bearing to cause corrosion;

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

22. The clearance of the bearing is too small, and it is too tight when rotating (the tightening sleeve is too tight);

23. There are pressure pits on the steel ball or roller (caused by striking the bearing with a hammer during installation);

24. The bearing is discolored and deformed when heated (caused by removing the bearing by heating with a spray gun);

25. The shaft is too thick and the actual fit is too tight (causing excessive bearing temperature or noise);

26. Insufficient lubrication (oil level is too low, improper storage causes oil or grease leakage through the seal);

27. The sizing block at the bottom of the bearing seat is not flat (causing deformation of the seat hole and even cracks in the bearing seat);

28. The diameter of the bearing seat hole is too large, and the actual fit is too loose (the bearing temperature is too high, and the outer ring slips);

29. The bearing seat hole becomes larger (the bearing seat hole of non-ferrous metal is stretched or becomes larger due to thermal expansion);

30. The shaft bears additional load (the shaft bears axial stiffness, or there are two fixed end bearings on one shaft);