The future of railway wheelset and axle testing – Part 2

1. The evolution of wheelset and axle NDT

Advancements in technology have dramatically enhanced the performance capabilities of ultrasonic axle testing (UAT) by introducing new technology and automated systems with permanent records, improving throughput speeds and traceability. One advancement is the solid axle mechanised tester (SAMT). When railway axles fail, the consequences can be disastrous. For safety, railway solid axles must be inspected regularly using non-destructive testing (NDT) methods to detect transversally oriented fatigue cracks. If inspecting from the lateral surfaces of the axle, methods such as ultrasonic testing (UT) or magnetic testing (MT) require coating, painting and the removal of accessories such as brake discs and gears to allow for proper coupling of the probe or inspection device. From the front face of the axle, only UT inspection is feasible because it is the sole method that can penetrate several millimetres of material. Unfortunately, solutions based on conventional UT often do not achieve the highest probability of detection (POD). This is because minimising the number of inspection angles and transducers may not result in an optimal inspection. Moreover, many specific set-ups and kits may be required for different inspection tasks^[1].

The inspection of railway wheelsets has also developed from manual advanced NDT methods such as phased array ultrasonic testing (PAUT) and eddy current array (ECA) testing to fully automatic ultrasonic wheel inspection systems for use during light maintenance without having to dismount the wheelset. When a train is on the maintenance track, the underfloor wheelset ultrasonic testing (UW-UT) system is run along the undercarriage of the train to automatically lift and rotate each wheelset. At the same time, twin robots position phased array (PA) probes on both wheels. In less than one minute, and with one rotation of the wheelset, the Focus PX instrument acquires the ultrasonic data and transfers it to the customised WIS software program. A minute after that, the automatic inspection report is ready for the operator to review^[2].

More intrusive overhauls for heavier maintenance can adopt dismounted wheelset ultrasonic testing (DW-UT) systems, where fatigue cracks in wheel flange, rim and plate areas can be evaluated using a combination of conventional and phased array ultrasonic testing, automatic operating, lifting, rotation and inspection of the disassembled wheelset, A/B scan, bar chart and wheel side-view data display and analysis, artificial intelligence (AI)-based automatic defect detection and reporting. The inspection time can be as little as ≤5 min per wheelset^[3].

2. The cost of maintenance 

The cost of maintenance can be high if repair requirements are not detected in time to avoid larger and more invasive repair measures. The cost is also hugely impacted by the time these vehicles spend out of service, resulting in a loss of earnings. So, it is essential that we improve with the times and adapt with faster, smarter and more efficient ways of overhauling rail vehicles to ensure that a high quality of overhaul is achieved more quickly and efficiently than ever before.

3. Conclusion

To be able to effectively maintain the rail industry in the future and keep up with the evolution of technology and the Fourth Industrial Revolution (Industry 4.0) with the integration and sharing of information between multiple networks and systems, we must embrace the advancements and invest in new technology. Our businesses will reap the benefits and we can be confident that our rail is as safe as it can be.

References

1. B Hughes, ‘Solid axle mechanised testers’, 2020. Available at: www.bakerhughes.com/waygate-technologies/ultrasonic-testing/portable-ultrasound-equipment/solid-axle-mechanized-testers-samt

2. B Kenaston, ‘Intelligent railway wheelset inspection using phased array technology – a customer story’, 13 May 2021. Available at: www.olympus-ims.com/en/insight/intelligent-railway-wheelset-inspection-using-phased-array-technologya-customer-story

3. DTEC GmbH, ‘Products overview’, 2021. Available at: https://dtec-gruppe.com/products/#dismounted-wheelset-ultrasonic-testing