CHARACTERIZATION OF SPHERICAL DEBRIS FROM ROLLER BEARINGS UNDER BOUNDARY LUBRICATION

ADRIAN URRESTARAZU; W. R. TUCKART; L. QUINZANI

Mar del Plata

Workshop; 3º International Workshop of Tribology; 2015

Asociación Argentina de Tribología

The detection of wear particles in a lubricant provides a powerful diagnostic technique for the finding of distress in critical mechanisms and thus preventing catastrophic failure by allowing timely maintenance [0]. The presence of wear particles in a lubricant can be easily revealed by ferrography and confirmed by electron microscopy, and their composition can be determined by X-ray energy analysis. On machines where there are many elements with rolling motion and where vibration and ultrasound techniques do not allow a reliable diagnosis to early failure (such as in low-speed gear-boxes in cement mills), ferrography plays a most important role. In general, the appearance of large numbers of spherical particles smaller than 10 m is associated with failures in rolling contact elements. However the physical process that generates these particles is yet not completely understood and leaves some questions [2,3]. In a previous work, we have found an appreciable number of metal microspheres with iron-oxygen and iron-chromium-oxygen elements on ferrograms made on oil samples from gear box in service. The question arised if these particles were from the bearing raceway that usually fails. To analyze this possibility, we began an experimental examination of wear debris from bearings under totally controlled laboratory conditions. The present work concentrates on examining the mechanism of formation and the source of generation of the microspheres and briefly describes the changes at various stages in the wear process.