Characterization of rolling bearing rotation and local defects exploiting their magnetic remanence

Rotational speed and defect monitoring are of crucial relevance for all the rotating machinery. Traditional sensors require to be mounted on or near the rotating bodies, exposing them to significant thermal and mechanical stress. In this work, a method has been developed to measure the angular velocity and to detect the presence of potential bearing defects from the analysis of the magnetic field generated by the residual magnetization of moving parts. To test such an approach, a dedicated experimental setup using a bare induction coil and a magnetoresistive device as separate sensing elements has been developed. This contactless technique provides reliable results and can achieve performance similar to or better than that of accelerometers, which are commonly used for this purpose. The presence of defects has been further assessed using white light interferometry. Finally, the results are discussed and compared with alternative techniques.