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

The pitted surface has a dull luster which appears on the rolling element surface or raceway surface.

Possible Causes Debris becomes caught in the lubricant Exposure to moisture in the atmosphere Poor lubrication Countermeasures Improve the sealing mechanism Filter the lubrication oil thoroughly Use a proper lubricant
Pitting 1

Part: Outer ring of a slewing bearing
Symptom: Pitting on the raceway surface
Cause: Rust

Pitting 2

Part: Ball of damage “Pitting 1”
Symptom: Pitting on the rolling element surface

Source: NSK