Belt pattern of electrical corrosion accompanied by pits on the raceway surface

Belt pattern of electrical corrosion accompanied by pits on the raceway surface - Bearing defects

Figure 1: Belt pattern of electrical corrosion accompanied by pits on the raceway surface.

Defect name: Electrical corrosion
Record No.: 1418
Type of defect (Internal/Surface): Surface
Defect classification: Bearing defects
Steel name: Steel
Steel composition in weight %: No data.
Note:
Damage conditions: When electric current passes through a bearing, arcing and burning occur through the thin oil film at points of contact between the race and rolling elements. The points of contact are melted locally to form “fluting” or groovelike corrugations which are seen by the naked eye. The magnification of these grooves will reveal craterlike depressions which indicate melting by arcing.
Possible cause: Electrical potential difference between inner and outer rings. Electrical potential difference of a high frequency that is generated by instruments or substrates when used near a bearing.
Measures: - Design electric circuits which prevent current flow through the bearings.
- Insulation of the bearing.
Part: Inner ring of a cylindrical roller bearing.
Symptom: Belt pattern of electrical corrosion accompanied by pits on the raceway surface.
Reference: Not shown in this demonstration version.