In the rail industry, ACFM technology is well established for inspection of axles, wheels, bogies and rails.
In the UK, where some of the highest quality standards exists, the technique has been accredited for use by Bombardier Transportation and Network Rail.
Surface breaking defects can occur, particularly on solid axles or in difficult access regions such as under earth-return brushes.
Axles can be inspected without paint removal, enabling testing to be carried out both on and off the vehicle. The simplest option involves a standard pencil probe mounted in a suitable holder. To speed up inspection, probes can be made containing many sensors. These array probes have the ability to scan a much larger area in a single pass.
Transverse cracking is likely on wheel rims and flanges.
Wheel rims and flanges can be inspected using similar techniques to axles. A standard pencil probe can be deployed manually by trolley, or mounted in a jig above a rotating wheel. However, inspection is speeded up considerably by the use of an array probe shaped to match the rim/flange geometry so that the whole surface is inspected in one pass.
Head checking is required where inclined cracks tend to be clustered together.
Bogies contain a large number of welds, usually of short length and quite often difficult to access. To inspect the welds, a variety of standard mini & micro pencil probes with differently angled or lengthened heads are used, depending on access available.
Inclined cracks across around the edge of the railhead and defect clusters can occur.
Specialist ACFM walking-stick probe was developed to report defect severity, allowing inspectors to distinguish important growth-potential cracks from often minor defect clusters.
Gauge Corner Cracking assessment
- ACFM Walking Stick
- U19 AMIGO instrument
- 0mm 8 channel flat array probe 5KHz
- Standard weld probe 5KHz
- Mini pencil probe 5KHz
- Encoder weld probe 5KHz
The ACFM Walking Stick instrument provides a thorough analysis of surface breaking rail-head defects. Defect pocket-depth analysis is automated and can discriminate between gauge corner cracking and other defect types.
The system utilises advanced Windows software, developed by TSC, which automatically analyses the data on-site and can produce yard-by-yard inspection summary reports.
In addition to the ACFM Walking Stick work, TSC worked closely with a major national rail maintenance company on general track related inspection and point and crossover inspection. In the limited time available to work on the railway, ACFM provided rapid, valid results and allowed engineering decisions to be made on the spot.
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AMIGO - Portable, rugged and versatile ACFM instrument. Options for dual frequency and array probes support.
Walking Stick- Complete Instrument, Probe, Laptop and deployment solution for rail inspection.
Bespoke Product Solutions for the Sector
TSC continues to extended application development of current products and work on the design and realisation of bespoke solutions and collaborative projects with other specialist engineering companies in the industry.
Example of a product solution developed within the rail sector:
- Bombardier Transportation wished to replace magnetic particle inspection of their train bogies with a technique which did not require removal and reapplication of paint.
- Demonstrations on a sample bogie showed that ACFM could be used for this purpose, but Bombardier requested modifications and additions to the standard equipment to meet its needs.
- The primary change was to add an automated defect recognition and sizing algorithm to assist the operator. Such a development is possible when specific geometries are being inspected on a regular basis.
- Other additions included office-based software to correlate inspection data from several operators, and customised reports.