Use of magnetic flux techniques to detect wheel tread damage

Rail vehicle wheelsets are regularly maintained to ensure their safe operation on track and prolong their life. This is achieved through measurements to inspect roundness, profile shape, rim thickness and visual inspections of surface damage. If necessary, wheels are re-profiled on a lathe to preserve the optimal wheel shape and remove any visible surface damage. Surface damage is difficult to classify visually, leading to highly subjective results. It is also not possible to establish defect depth through visual inspections. Magnetic flux leakage (MFL) technology has been successfully applied to the detection of defects in rails. This technology has been adapted for the evaluation of wheel damage, resulting in a fast and repeatable method of quantifying damage to railway wheels. This paper describes the theory behind the MFL technique and how it has been applied to the detection of wheel damage. This includes a summary of the assessment of the depth of damage into the wheel tread for a range of wheelsets. The benefits to train operators of adopting this technology are also presented.