Evident
Axle Inspection Made Easy with Phased Array Technology
This article first appeared in the Railway-News magazine, Issue 1 2023.
Rail car axles are critical components that encounter a high level of stress during operation. As such, ensuring their inspection and maintenance during manufacturing and service is of utmost importance.
Approached traditionally, non-destructive testing (NDT) of rail axles presents a laborious task using conventional methods such as magnetic particle inspection (MPI) or conventional ultrasonic testing (UT) approaches. In the case of MPI, reliable data can be gathered, but a full disassembly of the wheelset is required, which is both time-consuming and costly when rail car downtime is taken into account. UT on the other hand, enables axle inspection without disassembly, but yields less reliable data and remains time-consuming as multiple single element transducers are required to inspect critical areas for defects. Furthermore, UT can be costly due to the need for expensive gantry systems. In either case, these methods are imperfect when seeking to implement a robust axle inspection in a timely and cost-effective manner.
Axle inspection poses many challenges, yet is a central process for every rail maintenance depot to detect axle faults such as manufacturing flaws, defects and fatigue cracks. Since axle inspection is key to ensuring safety on the railways, solutions that can make the inspection process more convenient, while simultaneously detecting faults with high reliability, could provide great value to stakeholders in the railway maintenance sector.
Phased Array Ultrasonic Testing
Phased array ultrasonic testing (PAUT) is an advanced NDT method that can be harnessed for almost any test where conventional ultrasonic flaw detectors have traditionally been used, but is especially pertinent for axle inspection. Unlike conventional UT that is reliant upon multiple single element transducers, PAUT utilises probes that contain an array encompassing multiple elements. Rather than having to manually calibrate, move and adjust the transducer as is required in conventional UT, PAUT transducers can be calibrated, focused and swept electronically, greatly speeding up the inspection process.
