A magnetic method for detecting the onset of surface contact fatigue

Abstract This paper describes a magnetic detection system which has been developed for continuous monitoring of the surfaces of a system running under conditions where fatigue cracks are likely to occur. Experiments are described involving a disc-on-disc machine (which was made to simulate the contact conditions between gear teeth). The method is shown to be capable of detecting (i) initial surface fatigue cracks and (ii) the eventual pitting failure. It is also possible to use the detected signals to shut down the machine in order to facilitate microscope examination of the flaws to be carried out as soon as they are first detected. The method is compared with previously published attempts to detect and locate cracks and pits. The potentialities of the technique are also discussed.