Influence of Currents from Electrostatic Charges on WEC Formation in Rolling Bearings

White etching crack (WEC) early bearing failures occur when the rolling contact is subjected to a so-called additional load such as an electrical current flowing through the bearing, in addition to the pure rolling load (p(Hz)). Tests on rolling bearings showed that a low electrical direct current flow, such as that resulting from electrostatic charges, can lead to WEC failures in oil-lubricated roller bearings and greased ball bearings.The WEC formation in the performed tests was dependent on the current, electrical polarity, load type (rotating or stationary ring load), and bearing load. A black oxidation of the WEC critical bearing ring led to a significant increase in lifetime. Based on the findings, the failure hypothesis cathodic WEC fatigue for electrical direct current-initiated WEC failures was established.