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

When sudden overheating occurs during rotation, the bearing becomes discolored. Then, the raceway rings, rolling elements, and cage will soften, melt and deform as damage accumulates.

Possible Causes Poor lubrication Excessive load (Excessive preload) Excessive rotational speed Excessively small internal clearance Entry of water and debris Poor precision of shaft and housing Excessive shaft bending Countermeasures Study the lubricant and lubrication method Reinvestigate the suitability of the bearing type selected Study the preload, bearing clearance, and fitting Improve the sealing mechanism Check the precision of the shaft and housing Improve the mounting method

Seizure 1

Part: 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

Seizure 2

Part: Convex rollers of damage “Seizure 1”
Symptom: Discoloration and melting of roller rolling surface, adhesion of worn particles from cage
Cause: Insufficient lubrication

Seizure 3

Part: Inner ring of an angular contact ball bearing
Symptom: Raceway Discoloration, melting at ball pitch intervals
Cause: Excessive preload

Seizure 4

Part: Outer ring of damage “Seizure 3”
Symptom: Raceway Discoloration, melting at ball pitch intervals
Cause: Excessive preload

Seizure 5

Part: Balls and cage of damage “Seizure 3”
Symptom: Cage is damaged by melting, balls are discolored and melted
Cause: Excessive preload

Source: NSK