KEYWORDS

Roller Bearings, Gearbox, Electric Discharges SEM, TEM, DLC

ELECTRIC DISCHARGES IN BALL BEARINGS AND DAMAGES

The studies on bearing failures due to electric current is not new. Prashad made extensive studies on bearing failure due to electric current. For energy saving, use of electric motors which use bearings has increased. A bearing maker reports that the use of Variable Frequency Drives (VFDs) in industry has increased for reducing electricity costs since 1990’s and that more premature bearing failures have occurred due to electrical erosion. Another maker reports that bearing damages occur due to current passage in the use of roller bearings in wheelsets and traction motors in rail vehicles, direct current and alternating current motors, and generators of wind power. Damages by electric discharges also occur in sliding parts of automobile parts. Although many studies have been conducted on bearing failures, there is little metallurgical studies on the damaged parts by spark discharges of electricity.

AUTHORS 

Kenji Matsumoto, Honda R&D Co. Ltd., Haga-gun, Japan, Akira Sasaki, Maintek Consultant, Yokohama, Japan and Naoki Yoshida, Kyushu University, Kasuga, Japan