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NSK Europe Ltd.
Troubleshooting poster

Troubleshooting poster

Product catalog summary

Causes and Countermeasures for Operating Irregularities in Bearings

1. Flaking
Location: Inner ring of a spherical roller bearing
Symptom: Flaking of only one raceway over its entire circumference
Cause: Excessive axial load
Countermeasure: Reconfirm the bearing application and check the load conditions.

2. Axial Cracks
Location: Inner ring of a spherical roller bearing
Symptom: Axial cracks on raceway surface
Cause: Large fitting stress due to temperature difference between shaft and inner ring
Countermeasure: Check the application and use NSK TL series bearings (special steel).

3. Fretting
Location: Inner ring of a deep groove ball bearing
Symptom: Fretting on the bore surface
Cause: Vibration
Countermeasure: Check the interference fit.

4. Electrical Corrosion
Location: Inner ring of a tapered roller bearing
Symptom: Striped pattern of corrosion on the raceway surface
Cause: Electrical potential difference between inner and outer rings
Countermeasure: Insulation of the bearing.

5. Scoring
Location: Rollers of a double-row cylindrical roller bearing
Symptom: Scoring on the roller end face
Cause: Poor lubrication and excessive axial load
Countermeasure: Improve the lubricant and lubrication method and check the load conditions.

6. Cage Damage
Location: Cage of an angular contact ball bearing
Symptom: Pocket pillar fractures in a cast iron machined cage
Cause: Abnormal load action on cage due to misaligned mounting between inner and outer rings
Countermeasure: Check the mounting method.

7. False Brinelling
Location: Inner ring of a deep groove ball bearing
Symptom: False brinelling on the raceway
Cause: Vibration from an external source while stationary
Countermeasure: Secure the shaft and housing during transport, reduce vibration by preloading, use a suitable lubricant.

8. Rust and Corrosion
Location: Inner ring of a spherical roller bearing
Symptom: Rust on raceway surface at roller pitch
Cause: Entry of water into lubricant
Countermeasure: Improve the sealing mechanism.

9. Smearing
Location: Outer ring of a cylindrical roller bearing
Symptom: Smearing occurs circumferentially on raceway surface
Cause: Insufficient radial load, roller slipping due to excessive grease filling
Countermeasure: Improve the bearing clearance, improve the lubrication method, check load condition.

10. Denting
Location: Inner ring of a tapered roller bearing
Symptom: Small and large indentations over entire raceway surface
Cause: Debris caught in the surface
Countermeasure: Improve the sealing mechanism, filter the lubricating oil.

11. Creep
Location: Inner ring of a spherical roller bearing
Symptom: Creep accompanied by scoring of bore surface
Cause: Insufficient interference
Countermeasure: Check the interference and prevent rotation.

12. Mounting Flaws
Location: Inner ring of a cylindrical roller bearing
Symptom: Axial scratches on raceway surface
Cause: Inclination of inner and outer rings during mounting
Countermeasure: Center the relative mating parts during mounting.

13. Fracture
Location: Inner ring of a tapered roller bearing
Symptom: Fracture occurs at the cone back face rib
Cause: Large shock during mounting
Countermeasure: Improve the mounting method (shrink fit, use of proper tools).

14. Pitting
Location: Rolling element of a ball bearing
Symptom: Pitting occurs on the rolling element surface
Cause: Debris becomes caught in the lubricant
Countermeasure: Improve the sealing mechanism, filter the lubricating oil.

15. Seizure
Location: Inner ring of a spherical roller bearing
Symptom: Raceway is discolored and melted. Worn particles from the cage were rolled and attached to the raceway
Cause: Insufficient lubrication
Countermeasure: Check the lubricant and lubrication method.

16. Discoloration
Location: Inner ring of a 4-point contact ball bearing
Symptom: Bluish or purplish discoloration on raceway surface
Cause: Heat generation due to poor lubrication
Countermeasure: Improve the lubrication method.

Troubleshooting poster

Troubleshooting poster

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