Factors affecting brinelling and its detection in cylindrical roller element bearings

Abstract

Brinelling exists ID two fonns, namely true brinelling and false brinelling. Bearing damage due to false brinelling is a common problem and is known to occur on powerstations in Eskom.An example of false brinelling has recently been identified on the ejector pump motors at I.ethabo Pow'er station. True brinelling does not pose a problemto Eskom,and has therefore not been included in this study False brinelling is a special form of fretting and is found to occur in stationary roller element bearings subject to vibration. The vibration creates load fluctuations and varying degrees of relative motion within the bearings. As a result, small depressions or flutes are fonned in the race (Plate 1.1) which eventually lead to increased operational vibration and premature bearing failures. Previous studies do not makeany reference to factors affecting false brinelling in horizontally mounted bearings. The need for a better understanding of false brinelling has increased with the cold storage and partial cold storage of under utilized powerstations. This investigation approachesthe problemof false brinelling froma new angle. Horizontally mountedbearings have been used for testing as opposed to vertically mountedbearings used by other researchers. The effects of static bearing load, impedance,vibration amplitude and direction on false brinelling have been investigated. The study has shown that bearing impedanceand load do not have a significant influence on the rate of bearing damage,while vibration