Premature White Etching Crack Bearing Failures in Wind Gearboxes
Bearings in large industrial gearboxes sometimes fail, resulting in a failure mode known as white etching cracks (WEC) or sometimes called white structure flaking (WSF). The occurrence of premature failures is heavily discussed within the wind industry and independently investigated by wind turbine manufacturers, gearbox manufacturers, bearing suppliers as well as universities and independent institutes. Unfortunately, a consistent theory does not exist today. In this paper, influencing factors that can lead to WEC networks will be discussed. This is on the one hand done by reflecting bearing related aspects including chemical effects and material properties. On the other hand, application conditions are considered with special focus on wind turbine specifics. From this work it is clear that a generalized simple root cause is counterproductive; pinpointing the need to carefully evaluate each WEC case in the light of the corresponding application.