FERROGRAPHIC ANALYSIS OF FAILURE PROCESS IN A FULL-SCALE JOURNAL BEARING

The failure process of a full-scale journal bearing, caused by insufficient oil supply to the interface, was monitored and analyzed with ferrography and the spectrometric oil analysis procedure (SOAP). The temperature of the bearing metal and the journal deviation were also measured to monitor the behavior of the bearing. Wear debris was observed and analyzed in detail with a scanning electron microscope and a wavelength-dispersive X-ray analysis facility. It was found that ferrography and SOAP could promptly detect the failure symptoms. Ferrography could also detect the progressive failure, that is the progress of damage. With the progress of failure, the types, sizes and composition of wear debris changed significantly; a small amount of rubbing debris was generated from the journal at the normal state, much cutting and plate-like debris from the journal, some plate-like debris from the bearing at the early stage of failure, much polymer-like debris containing both the journal and bearing materials at the middle stage and much cutting, plate-like and oxide-like debris from both the journal and lining metal (steel) at the catastrophic stage. The wear mechanisms are discussed.