Monitoring the onset and propagation of natural degradation process in a slow speed rolling element bearing with acoustic emission

The monitoring and diagnosis of rolling element bearings with the high frequency acoustic emission (AE) technology has been ongoing since the late 1960s. This paper demonstrates the use of AE measurements to detect, locate, and monitor natural defect initiation and propagation in a conventional rolling element bearing. To facilitate the investigation a special purpose test rig was built to allow for accelerated natural degradation of a bearing race. It is concluded that subsurface initiation and subsequent crack propagation can be detected with the AE technology. The paper also presents comparative results between AE and vibration diagnosis.