Metrology with High Energy Industrial Computed Tomography

Advanced manufacturing is introducing new challenges for testing and inspection. Today’s parts are not only more complex and often rely on mixed material strategies, but must still be manufactured to exacting standards. Accurate measurement is thus key for complex components, ensuring dimensions are within tolerance. Traditional inspection methods and destructive testing are often not feasible options, so how can you measure what you cannot reach?

Nondestructive testing with industrial computed tomography (CT) is a powerful technique for metrology of parts with complex external and internal geometries. As an x-ray imaging technology, CT has fewer material restrictions and takes less time than other methods to measure even complex dimensions like cylindricity and concentricity/coaxiality. CT also generates data for applications like defect identification and actual to nominal comparisons, allowing for both dimensional and material quality control with a single scan.

CT is known for its versatility and speed, but it does have some limitations with respect to size and portability. Parts must be able to fit into cabinet type CT machines, which are often bulky and cannot be easily transported. However, recent advancements with high energy industrial computed tomography are helping overcome these previous restrictions, expanding the range of inspection possibilities.

Exterior view of high energy industrial CT system at Jesse Garant

High energy computed tomography operates on the same principles as lower energy CT but uses x-ray sources in the mega electron volt (MeV) range. High energy CT allows for internal inspection of parts that cannot fit inside cabinet systems, useful for metrology of larger components like engine blocks, turbine blades, and mixed material assemblies.

The technology can also penetrate denser materials such as high strength alloys and results in improved image quality with cleaner separation of mixed materials. The advantage is due to the  imaging artifacts common, with lower energy systems, being greatly reduced at energies above 1 MeV.

Jesse Garant Metrology Center, an NDT and metrology company based in Dearborn, Michigan USA and Windsor, Ontario, Canada has recently launched their own high energy industrial CT system, becoming the only private laboratory in the world to offer this exclusive service.

Their new system is the first of its kind to pair a 3MeV cone-beam linear accelerator x-ray source with a large format flat panel digital detector, able to inspect parts up to 44.5 inches in diameter by 63 inches in height. The new capability is ideal for internal inspection of engineered parts, composites, castings, and 3D printed parts in aerospace, defense, automotive, and oil and gas industries.

“We’re helping manufacturers qualify and validate parts that either weren’t possible because of limitations with existing technologies or weren’t feasible because the service was too costly or took too much time,” says President Jesse Garant. “We aim to support innovations within advanced manufacturing by providing internal inspection of parts that would otherwise go into production without proper inspection.”

The new system is able to accommodate rapid large-format inspection, resulting in a drastic reduction in scanning time for mid-size to large parts and assemblies. While existing high energy CT systems may take 4-16 hours to complete scans, the new system is able to scan parts in less than an hour.

The technology will provide accurate and precise metrology data for 3D measurement of external and internal part geometries. Calibrated with NIST traceable artifacts, the new machine will help manufacturers maintain the quality and consistency of pre-production and production parts requiring dimensional validation. The system will also support PPAP and AS9102 Form 3 first article reporting requirements specific to the automotive and aerospace industries.

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