Ultrasonic and electromagnetic inspections of railway hollow axles

The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, new inspection technologies based on Ultrasonic Testing and Electromagnetic techniques suitable for the inspection of hollow axles have been developed. The key difference between the developments of this technology compared to other existing manual inspection techniques is that the inspection can be conducted in-situ without removing the axles and associated bogies from the train and with minimal disassembly of the wheelset. Both kinds of probes (UT and EM) have been developed to detect cracks of 0.5 mm deep anywhere within the axle. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to the surface breaking shallow defects. Therefore, the electromagnetic technique is used to detect surface breaking cracks that cannot be detected by ultrasonic technique.