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.
Straight line scratches on surface of raceways or rolling elements caused during mounting or dismounting of bearing.
Dull or cloudy spots appear on surface along with light Wear. From such dull spots, tiny Cracks are generated downward to a depth of 5-10 ｵm. Small particles fall off and minor Flaking occurs widely.
Smearing is surface damage which occurs from a collection of small seizures between bearing components caused by oil film rupture and/or sliding.