After a long-term summary by technicians, there are 27 reasons for the bearing noise, and there may be many that we have not encountered before, and we will make up for it in the future. 1. Impurities such as sand or carbon particles are mixed into the bearing, which acts as an abrasive. 2. Water, acid or paint and other dirt are mixed into the bearing, which plays a corrosive effect; 3. The clearance of the bearing is too small (the matching selection is 4. Incorrect selection of lubricating oil or grease; 5. Insufficient lubrication (the oil level is too low, the oil or grease leaks through the seal); 6. The bearing is flattened by the seat hole (roundness of the seat hole) bad, or the seat hole is not twisted straight); 7. The bolster on the bottom surface of the bearing seat is not flat (resulting in deformation of the seat hole or even cracks in the bearing seat); 8. There are debris in the bearing seat hole (remaining chips, dust particles, etc. ); 9. The seal ring is eccentric (contacts adjacent parts and rubs); 10. The bearing is subjected to additional load (the bearing is axially tightened, or there are two fixed end bearings on one shaft); 11. The heat of the shaft Excessive elongation (the bearing is subjected to static and indeterminate axial additional load); 12. The clearance of the bearing is too small, and the rotation is too tight (the adapter sleeve is over-tightened); 13. The shaft s is noisy (the end face of the roller) Or the steel ball slips); 14. The fit between the 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 (it touches the seal of the bearing and rubs); 16 . The shoulder of the seat hole is too large (the seal of the bearing is distorted); 17. The clearance of the labyrinth seal is too small (friction with the shaft); 18. The teeth of the lock washer are bent (the bearing does not touch the bearing. 19. The position of the oil slinger is not suitable (it touches the flange cover and friction occurs); 20. There is a pressure pit on the steel ball or roller (caused by hitting the bearing with a hammer during installation); 21. Bearing There is noise (interference from external vibration sources); 22. The bearing is heated and discolored and deformed (caused by using a spray gun to heat and disassemble the bearing); 23. The shaft is too thick and the actual fit is too tight (causing the bearing temperature is too high or noise); 24. The bearing is noisy (the bearing has fretting wear). 25. The diameter of the bearing seat hole is too large, and the actual fit is too loose (the bearing temperature is too high - the outer ring slips); 26. The bearing seat hole becomes larger (the non-ferrous metal bearing seat hole is enlarged, or becomes larger due to thermal expansion) ; 27. The diameter of the seat hole is too small (causing the bearing temperature to be too high).