Bearing Failure RCA: Scoring

 

When a rolling bearing is damaged during machine operation, the entire machine or equipment can seize or malfunction. Since bearings that fail prematurely or unexpectedly cause trouble, it is important to be able to identify and predict failure beforehand, so that preventive measures can be adopted.

Damage Condition

Scoring is surface damage due to accumulated small seizures caused by sliding under improper lubrication or severe operating conditions. Linear damage appears circumferentially on the raceway and roller surfaces. Cycloidal shaped damage on the roller ends and Scoring on the rib surface contacting roller ends also occur.

Possible Causes

  • Excessive load, excessive preload
  • Poor lubrication
  • Particles are caught in the surface
  • Inclination of inner and outer rings
  • Shaft bending
  • Poor precision of the shaft and housing

Countermeasures

  • Check the size of the load
  • Adjust the preload
  • Improve the lubricant and the lubrication method
  • Check the precision of the shaft and housing

 

Scoring 1

Part: Inner ring of a spherical roller bearing
Symptom: Scoring on large rib face of inner ring
Cause: Roller slippage due to sudden acceleration and deceleration

 

Scoring 2

Part: Convex rollers of damage “Scoring 1”
Symptom: Scoring on roller end faces
Cause: Roller slippage due to sudden acceleration and deceleration

 

Scoring 3

Part: Inner ring of a tapered roller thrust bearing
Symptom: Scoring on the face of inner ring rib
Cause: Worn particles mixed with lubricant and breakdown of oil film due to excessive load

 

Scoring 4

Part: Rollers of a double-row cylindrical roller bearing
Symptom: Scoring on the roller end faces
Cause: Poor lubrication and excessive axial load

 

Scoring 5

Part: Inner ring of a spherical thrust roller bearing
Symptom: Scoring on the rib face of inner ring
Cause: Debris caught in surface and excessive axial load

 

Scoring 6

Part: Convex rollers of damage “Scoring 5”
Symptom: Scoring on the roller end faces
Cause: Debris caught in surface and excessive axial load

 

Scoring 7

Part: Cage of a deep groove ball bearing
Symptom: Scoring on the pressed-steel cage pockets
Cause: Entry of debris

 

Source: NSK