The bearing cannot be directly observed during operation, but the abnormality of the bearing can be observed through noise, vibration, temperature, lubricant and other conditions. Representative examples of bearing damage;Causes and Measures of Bearing Damage
Causes and Measures of Bearing Damage
1. Crack defect
Some notches have cracks. The reasons are: the impact load of the main engine is too large, and the interference between the main shaft and the bearing is large; There are also cracks caused by large peeling friction; Poor accuracy during installation; Improper use (using copper hammer, clamping in large foreign matters) and friction cracks.
Countermeasures: check the service conditions, set appropriate interference and check the material, improve the installation and use methods, and check the lubricant to prevent friction cracks.Causes and Measures of Bearing Damage
2. Metal stripping on raceway surface
Peeling of running surface. After stripping, it is obviously concave and convex. The reason is that the bearing rolling element and the inner and outer ring raceways are subjected to periodic fluctuating load, resulting in periodic contact stress. When the number of stress cycles reaches a certain value, fatigue peeling occurs on the working surface of rolling element or inner and outer race raceway. If the load of the bearing is too large, it will aggravate this fatigue. In addition, improper bearing installation, shaft bending and raceway peeling will also occur.Causes and Measures of Bearing Damage
Countermeasures: re study the service conditions and select the bearing and clearance, and check the machining accuracy, installation method, lubricant and lubrication method of the shaft and bearing housing.Causes and Measures of Bearing Damage
The bearing is heated and discolored, and then burns and cannot rotate. The causes of burns are generally insufficient lubrication, unqualified or deteriorated lubricating oil quality, and too tight bearing assembly. In addition, the clearance is too small and the load is too large (large preload) and the roller deflects.Causes and Measures of Bearing Damage
Countermeasures: select the appropriate clearance (or increase the clearance), check the type of lubricant, ensure the injection amount, and check the service conditions to prevent positioning error and improve the bearing assembly method.Causes and Measures of Bearing Damage
4. Broken cage
The rivet is loose or broken, and the rolling element is broken. The reasons are: excessive torque load, insufficient lubrication, frequent speed change and large vibration, the bearing is installed in an inclined state, and foreign matters are stuck.
Countermeasures: find out whether the service conditions and lubrication conditions are appropriate, pay attention to the use of bearings, and study whether the selection of cage is appropriate and whether the rigidity of bearing housing meets the load requirements.
The inner diameter surface or outer diameter surface slips, resulting in mirror or discoloration and sometimes jamming. The reasons are: insufficient interference at the fitting, insufficient fastening of the sleeve, abnormal temperature rise, excessive load of the main engine, etc.
Countermeasures: re study whether the interference is appropriate, check the service conditions, and check the accuracy of the shaft and bearing housing.
6. Rust corrosion
Local rust or rolling on the surface. The reasons are: poor storage state, improper packaging, insufficient rust inhibitor, invasion of water, acid solvent, etc., and directly holding the bearing by hand.
Countermeasures: prevent rust during storage, repack regularly or irregularly, strengthen sealing performance, check lubricating oil regularly, replace unqualified or deteriorated oil in time, and use bearings correctly.
7. Bearing indentation
Damage state: dents on the raceway surface or rotating surface when biting into small metal powder, foreign matters, etc. Due to the impact during installation, a concave surface (Brinell hardness indentation) is formed on the spacing of the rolling elements.
Cause: foreign matters such as metal powder bite in. Excessive impact load during assembly or transportation.
Measure: impact the shaft sleeve. Improve the sealing device. Filter the lubricating oil. Improve assembly and use methods.Causes and Measures of Bearing Damage
8. Bearing wear
Damage state: the so-called wear is the wear of raceway surface or rolling surface, roller end face, shaft ring surface and concave surface of cage caused by friction.
Cause: development caused by foreign matter intrusion, rust and electric corrosion. Poor lubrication. Slippage caused by irregular movement of rolling elements.
Measures: improve the sealing device. Clean the bearing housing. Fully filter the lubricating oil. Check the lubricant and lubrication method. Prevent non-linearity.
9. False Brinell indentation of bearing
Damage state: during micro vibration, the wear of the contact part between the rolling element and the raceway wheel develops due to vibration and shaking, resulting in impressions accumulated like Brinell indentation.
Cause: during transportation, the vibration and swing of the bearing when it stops running. Oscillating motion with small amplitude. Poor lubrication.
Measures: fix the shaft and bearing housing during transportation. The inner ring and outer ring shall be packed separately during transportation. Add preloading to reduce vibration. Use appropriate lubricant.
10. Bearing burns
Damage state: the raceway wheel, rolling element and cage are heated sharply during rotation until they change color, soften, deposit and damage.
Cause: poor lubrication. Excessive load (excessive preloading). Excessive speed. Too small a gap. Intrusion of water and foreign matters. The accuracy of shaft and bearing box is poor and the deflection of shaft is large.
Measures: study lubricants and lubrication methods. Correct the selection of bearings. Study fit, bearing clearance and preloading. Improve the sealing device. Check the accuracy of the shaft and bearing housing. Improve installation methods.Causes and Measures of Bearing Damage
11. Bearing rust and corrosion
Damage state: the rust and corrosion of bearings include pit rust, overall rust and corrosion on the surface of raceway wheel and rolling element.
Cause: invasion of water and corrosive substances (paint, gas, etc.). Improper lubricant. Water droplets are attached due to the condensation of water vapor. Stop when it is hot and wet. Poor rust prevention during transportation. Improper storage status. Improper use.
Measures: improve the sealing device. Study lubrication methods. Rust prevention measures during shutdown. Improve storage methods. Pay attention when using.
12. Bearing discoloration
Damage state: discoloration of raceway wheel, rolling element and cage due to temperature rise and lubricant reaction.
Cause: poor lubrication. Reaction with lubricant causes hot oil immersion. The temperature rises greatly.
Measures: improve lubrication methods.
As long as we avoid the above situations and maintain the bearing regularly, we can normally ensure the service life and performance of the bearing.