Electrical Erosion

Damage Condition	Possible Causes	Countermeasures
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.	Electric current passing through a bearing	Design electric circuits which prevent current flow through the bearings Insulate the bearing

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Part: Inner ring of a tapered roller bearing
Symptom: Striped pattern of corrosion occurs on the raceway surface

Part: Tapered rollers in damage “Electrical Erosion 1”
Symptom: Striped pattern of corrosion occurs on the rolling surface

Part: Inner ring of a cylindrical roller bearing
Symptom: Belt pattern of electrical corrosion accompanied by pits on the raceway surface

Part: Balls of a deep groove ball bearing
Symptom: Dark color covering the entire ball surfaces