How the Rail Industry can Benefit from Embracing Portable Metrology Solutions

The scale of heavy industrial manufacturing is in a class of its own. Large equipment sizes and weights create unique challenges, while component complexity is just as high as often seen in smaller machine production. Manufacturers are called upon to achieve a delicate balance between these two aspects of production, using robust production and quality assurance tools that can quickly complete large jobs but nevertheless achieve production accuracy to within fractions of a millimetre. On the line is the safety of operators and passengers – there’s no room for compromising on quality in this sector.

The current line-up of portable metrology tools on offer from Hexagon offers clear benefits within a number of important railway production applications – solutions that confidently walk the fine line where quality drives productivity instead of hindering it. Our range has clear potential to enable rail products to be built faster and with less rework, decreasing costs and improving production throughput.

Chassis and Frame Integrity

For the railcar to have stability and reliability on the track, the dimensional integrity of the chassis and frame is critical. But making such measurements to a useful level of accuracy has typically been a time-consuming process because of the extra-large scale of railcar production.

Laser trackers such as the Leica Absolute Tracker AT960 or the Leica Absolute Tracker AT403 offer the flexibility to make these measurements quickly, easily and accurately. Their extremely large measuring volumes – up to 320 metres in diameter for the AT403 – allow the collection of many data points with no need to reposition the laser tracker. And when combined with either the Leica T-Probe or Leica B-Probe, these systems also allow for easy hidden point measurements, within a measurement volume of up to 60 metres in diameter for the T-Probe.

This large-scale flexibility makes the collection of measurement data considerably faster, and therefore makes it easier to move the measurement process upstream to an early enough stage of production that alterations can be made relatively conveniently, without significant wastage of time or resources.

The Importance of Coach Construction

For ensuring good acceleration performance as well as the overall stability of a railcar, accurate coach construction is vital. Beginning at the welding phase, the combination of non-contact direct scanning and traditional reflector measurement offered by the Leica Absolute Tracker ATS600 can deliver a smooth build and adjust process that is significantly faster than typical alternative methods that call for more expensive measurement equipment and more personnel.

When the coach frame is joined, such laser trackers can be used to level the coach to avoid torsion. Due to the size of the welds involved, it’s often easy to miss points in the inspection process that are simply out of range for traditional 3D laser scanners, touch probes or reflectors. The Leica Absolute Tracker ATS600 is ready to meet this challenge with a unique working principle that can accurately locate a point in 3D space with metrology-grade accuracy without the need for a reflector at the point of measurement.

By first accurately locating the frame within the workspace using reflector measurement, and then monitoring the adjustment process from a distance with direct scanning, operators will always have a reliable overview of the construction and the necessary adjustments. With no need to constantly go back to the frame with a sensor, operators will find it much faster and easier to correctly align the extremely large and difficult to manoeuvre parts involved in railcar production.

Windscreen Geometry Fit

High-speed trains are usually designed to have sophisticated three-dimensionally moulded windscreens to deliver better aerodynamics and therefore efficiency. The fit and finish of these panels are imperative to the safety and long-term performance of the railcar. A Leica Absolute Tracker AT960 paired with a Leica Absolute Scanner LAS-XL is the ideal solution for aligning the complex geometries of these windscreen panels. With its extra-large stand-off distance of 1000 millimetres and ultra-wide measuring width of 600 millimetres, the LAS-XL allows a single operator to precisely check the alignment of a large windscreen within minutes.

For less demanding screen geometries, the metrology-grade non-contact measurement functionality of the Leica Absolute Tracker ATS600 is again a convenient solution, particularly for large cars where an operator would have difficulty reaching the highest measurement areas. And with the selective scanning ability of the ATS600, the target measurement area can be easily reduced to cover only the windscreen area, avoiding unnecessary data acquisition and analysis.

Wheelset and Track Profiles

Train wheelsets and rail infrastructure are typical high-wear parts that have a significant influence on passenger comfort and safety as well as noise and ride. Profiles of wheels, brake discs, rails and switches are therefore regulated by recurring measurement operations under demanding operating conditions. Efficient wheelset profile measurement can drive timely maintenance actions and help minimize train downtime, as well as ensuring a smooth and safe journey for rail passengers.

The contactless NEXTSENSE CALIPRI Profile measuring devices such as the CALIPRI C40 / C41 / C42 and the CALIPRI Prime meet the requirements of the rail industry by offering a simple, reproducible wear inspection method for the entire wheel/rail system. These specialised rail profile measurement devices are widely used for wheel profile inspection, brake disc measurement, wheel distance measurement, wheel wear inspection and rail wear inspection.

Bogie Measurements

Often missed by the average passenger, railway bogies are an essential part of the train and its performance. Different equipment, depending on sizes and tolerances, is used to measure the length, width, height difference, positions, and diagonals of the bogie construction. Due to the many configurations and hard-to-reach areas, the Leica Absolute Tracker AT403 with Leica B-Probe and Absolute Arm are both good solutions for measurements of these wheelset elements, providing support, stability and improved ride quality of the locomotive.

Interior and Internal Component Verification

The interior components of railcars are a significant factor in keeping passengers and crew safe and comfortable. Portable metrology solutions can provide a significant advantage in the fast and proper installation of seats, tables, and overhead luggage compartments. With its long operating range of up to 20 metres from the laser tracker and its extended one metre stand-off distance, the Leica Absolute Scanner LAS-XL is ideal for such tasks, allowing the operator to measure easily from within the carriage, quickly assuring the correct installation of all interior components.

Alternatively, a lightweight and easily repositioned Absolute Arm system can be easily positioned inside a train carriage and is ideally suited to such tasks as interior fitting flush and gap measurement, as well as measurement of small engine components. And a portable measuring arm even offers a solution before the installation stage that can be used to improve the construction of carriage interiors or engine parts. With the virtual assembly capabilities of an Absolute Arm system used in conjunction with an appropriate software package, the correct geometry of internal components can be assured ahead of time, making installation a more straight-forward task.

Portable Metrology as a Rail Industry Solution

Our range of portable measurement tools offers a range of solutions in the rail production sector, chiefly because of the large measurement volumes, reaches and stand-offs that make them uniquely suitable for such large-scale tasks. Any one of these devices, or perhaps several of them in concert, have the potential to make a huge difference in the way railcar components are made, offering more accuracy and resulting in reduced costs and less rework and an overall higher level of reliability and productivity.