Aircraft safety depends on reliable parts

Many people fly regularly on business or travel, but have you ever wondered about what goes into a commercial aircraft? There are said to be about three million parts in a medium- or large-sized aircraft, which is almost impossible to imagine. Yet aircraft are also described as the "safest of all vehicles," with each part needing to be completely reliable. That means careful quality inspection is an indispensable part of the manufacturing process — for every component.

Components that play a crucial role are turbine blades, which conduct the high-pressure, high-temperature gas produced by the jet engine combustor. Unless turbine blades are manufactured to the exact design specifications, not only will their energy conversion efficiency be reduced, but unexpected problems may also arise. As they are exposed to temperatures as high as about 1,000°C/1,832°F, the thickness of blades is designed to ensure an optimum balance between the strength of their entire surface and their cooling ability, with a strictly defined margin of error. Of course, there is also a risk of structural defects such as cracks and cavities shortening the life of blades. It is necessary to strictly inspect the accuracy of the blade shape, wall thickness, as well as detect structural defects. All items in the manufacturing process are subject to these inspections.

These inspections are generally performed by visualizing the internal structure using X-rays and quantifying the dimensions as a three-dimensional shape using CT based on the image data. However, turbine blades are made of high-density materials, such as single-crystal alloy, and cannot be inspected using conventional X-ray/CT inspection systems. That's where Nikon's XT H 450 CT inspection system, equipped with an X-ray source that generates high-power X-rays, comes into play.

Non-destructive, non-contact inspection to maintain manufacturing quality

One of the key features of the XT H 450 is that it acquires images that are detailed even when enlarged since it employs a micro-focus X-ray source. Moreover, as the world's only system with a high-power, micro-focus 450 kV X-ray source, the XT H 450 is able to inspect high-density metals with high accuracy, and can be used to analyze the internal structure of turbine blades.

Expanding applications as an "eye" for maintaining quality

Looking into the future of various fields with X-ray/CT inspection technology

"The major part of developing X-ray/CT inspection systems is probably the problem solving. There's usually no obvious right answer, so we continue to experiment until we find something. We often talk about "peeling the onion." It's a case of taking the problem and breaking it down into smaller chunks so you can achieve small successes one after another.

We started looking at various industries, moving across to automotive. We arranged tie-ups with the Formula 1 companies quite early, and some major Formula 1 companies are using our systems during development of their cars. They're at the cutting edge, and now that we've built up experience of working in such a highly regulated, safety-conscious industry, I believe it will become the foundation for new product development in the future.

There's a wide range of industries that can benefit from X-ray/CT inspection technology, outside of the manufacturing sector. For example, archeology, history and art. Geology is another area that could grow.
It's much more efficient if you can CT a rock core and virtually deconstruct it. In soil science, you can also use CT to see how plant roots grow over time.
It's important for us to keep in touch with other industries that might take us to new leads and challenges in the future."

• *Nikon X-Tek Systems Ltd.: Develops and manufactures X-ray CT and other three-dimensional metrology products.

Originally published: January 7, 2019.