AXLEINSPECT

Development of novel inspection techniques for train axles

The structural integrity of train axles is of great importance to the railway industry. A series of accidents directly related to the failure of axles has given rise to a greater demand for their inspection and maintenance. Currently, the most common non-destructive test (NDT) techniques for axle inspection in the field are visual inspection and magnetic particle inspection. However, these processes require the wheels and other axle auxiliary components to be removed (axle boxes, bearings, disc brakes, etc.) from wagons and locomotives in order to facilitate access to the inspection area. The dismantling operation of all the axle components is a long and costly operation. Furthermore, there is evidence that these dismantling and assembly operations could give rise to future reliability problems on the axle. Therefore, and with the aim of minimising the interruption of train services and maintaining safety, train operators require frequent and regular inspection methods that allow rapid inspection with the least number of dismantling operations.

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THE CHALLENGE

The aim of the AxleInspect project is to develop new inspection techniques based on electromagnetic technologies and phased array ultrasonics, suitable for both solid and hollow axles. For solid axles, the inspection techniques to be developed have been based on phased array ultrasonic technologies (internal cracks), gaining access from the free end of the axle in order to eliminate the dismantling process. For hollow axles, the inspection techniques to be developed have been based on electromagnetic technology (surface cracks) and ultrasonic technology (internal cracks), gaining access from inside the axle.
Ideko-IK4 is responsible for the design of a prototype that integrates both inspection technologies (electromagnetic and ultrasonic). This prototype has been evaluated both in the laboratory and in service (railway maintenance workshops). The inspections in the laboratory of both the hollow axle and solid axle were done at Ideko and subsequently the test was performed in England. In addition to designing the prototype, Ideko-IK4 was responsible for the design of software for carrying out, analysing and assessing the inspections.

THE RESULT

High-speed trains, for example, are fitted with hollow axles. The researchers had to develop special sensors to inspect the internal bore and the outer diameter of the part. To carry out this challenge, in IK4-IDEKO we combine two different techniques: ultrasound and electromagnetic techniques. Ultrasound allows us to inspect the outer surface of the axle; electromagnetic technology on the other hand inspects the internal surface. All these data are processed with one single software, also developed by IDEKO-IK4, responsible for analysing and assessing all data collected during inspections of the two solutions developed in the project. This guarantees 100% analysis of the axle.
Thanks to the new developments it is no longer necessary to disassemble the train in the depot for inspection, because with the new scanner it is possible to simply access the shaft, connect the scanner and examine the full axle body.