Midwest Manufacturing News • Mar 22 • Nondestructive Inspection of Large Components

Nikon Metrology’s industrial microfocus X-ray CT inspection solutions are now enhanced with an offset CT reconstruction algorithm to deliver increased scan speed and image resolution.

“When using X-ray CT (computed tomography) for non-destructive quality control of larger components like aluminum castings or battery modules for electrical vehicles, the challenge is to shorten inspection cycle times without compromising resolution,” said a company spokesperson. “One prerequisite for achieving this is high X-ray intensity, or flux.”

In Nikon Metrology’s range of Xray CT systems, a rotating target can already triple the flux for a given focal spot size, and the flux can be further increased by motorized FID (focal spot to imager distance), which brings the detector closer to the source at the push of a button.

With the release of an offset CT reconstruction algorithm in the latest version of the manufacturer’s Inspect- X software, not only can larger components be scanned, but it can also be performed at higher geometric magnification. The Offset.CT module is available on all Nikon Metrology X-ray CT systems from 180 kV through to 450 kV.

“With this unique combination of the latest Rotating.Target 2.0, adjustable FID and Offset.CT, which cannot be found in any competitive industrial CT system, cycle times are significantly reduced, and better resolution is achieved, even when processing large and complex components,” said the spokesperson.

Offset.CT is a scanning method that allows small or large components to be inspected fully while only part of the sample is within the field of view (FOV) during rotation. The component is placed such that only just over half of the object lies within the X-ray cone beam, allowing a much wider FOV and reconstruction volume.

“Compared with traditional CT, this has two main benefits for component inspection,” said the spokesperson. “First, larger components, even those wider than the detector itself, can be scanned without having to use a larger CT machine. Secondly, it allows the component to be placed much closer to the X-ray source, allowing higher magnification and therefore significantly increased voxel resolution. Consequently, a broader range of sample sizes can be scanned at high resolution.

“It is therefore easier to perform a wide range of critical inspection tasks, including identification of small internal defects, measuring features in the interior of complex components, or detecting deviations from a nominal CAD model, even when dealing with large components.”

Adjustable FID is a standard feature in Nikon Metrology 225kV XT H systems and Large Envelope CT systems up to 450kV. The benefit of shortening the distance between the source and the detector using motorized FID functionality is that the X-ray flux is increased. It serves to improve the signalto- noise (SNR) ratio and the image quality of digital radiographs and 3D voxel data, in addition to allowing increased scanning speed.

Nikon Metrology’s proprietary Rotating. Target 2.0 is able to generate Xrays that are three times more powerful for a given microfocus spot size, without reducing image resolution. Scan times are consequently shorter and/or denser samples can be penetrated. Rotating. Target 2.0 features a maximum voltage of 225kV and a maximum power of 450W, but for larger and denser components a microfocus 450kV rotating target X-ray source is available.