Estimation of the spall size in a rolling element bearing

Rolling element bearings are essential components of rotating machinery. Therefore, preventing bearing failure is a subject of great interest. Effective failure prevention requires maintenance decisions that are based on both a diagnosis of bearing faults and an estimation of the fault severity. Since spalling of raceways is a common bearing failure mechanism, the objective of this study is the estimation of the spall width based on vibration analysis. During each interaction of a rolling element with a spall located on the bearing raceway, two events occur. The first event is the entrance of the rolling element into the spall, which is followed by a system response to a step function. The second event is the exit of the rolling element from the spall, which is followed by a system response to an impulse. The time lag between these events can be used for an estimation of the spall size. Several studies have been published on this subject, which propose sophisticated signal processing algorithms. A new method based on the physical insights obtained from simulations of a dynamic model of faulty bearings is proposed.