Damage Condition

When electric current passes through a bearing, arcing and burning occur through the thin oil film at points of contact between the raceway and rolling elements. The points of contact are melted locally to form “fluting” or groove-like corrugations which can be seen by the naked eye.
Magnification of these grooves reveals crater-like depressions which indicate melting by arcing.

Possible Causes

• Electric current passing through a bearing

Possible Causes

• Electric current passing through a bearing