Laminography is a faster and cheaper alternative to 3D CT inspection. It uses 2D X-ray scans to provide 3D reconstructions in minutes vs. hours. However, most such inspections are limited to cabinet machines and parts that can fit inside those enclosures. Robot CT, using specially programmed collaborative robots, provides the same speed and resolution as traditional laminography, but moves beyond small planar objects to large and complex 3D parts.
Industrial X-Ray CT Scanning
Industrial X-Ray computed tomography (CT) is a powerful imaging technique that generates detailed 3D reconstructions of objects by capturing a series of 2D X-ray images at multiple angles. This method provides a comprehensive view of the internal structure of an object, enabling defect detection, precise measurements, and material analysis. X-ray CT provides high-resolution imaging and inspection of complex 3D structures, enabling the identification of internal defects and thorough analyses for a wide range of applications in aerospace, automotive, electronics and other industries.
The drawbacks of X-ray CT include the high cost of cabinet systems and/or scanning services, as well as longer scan times for complex parts and significant time and computing power to process the data to enable defect identification and material analysis, etc.
X-Ray Laminography
In contrast, X-ray laminography involves capturing 2D X-ray images at selected angles to reconstruct focused cross-sectional views of specific planes within an object. It is a simpler, faster method that is particularly useful for inspecting thin or flat objects, such as circuit boards, electronic components, and layered materials. With its ability to provide high-resolution cross-sectional images, laminography offers a cost-effective and efficient solution for targeted inspections that require detailed analysis of specific areas within a part or structure.
Some limitations of traditional laminography include more limited 3D visualization versus fully 3D CT scanning, as well as reduced depth information and lower resolution and accuracy versus inspection of circular or rotational parts. This is because the X-ray source must be moved away from the planar or complex-shaped object as it is rotated within the cabinet in order to avoid collisions, thus reducing resolution.
Omni NDE Robot CT
Omni NDE has incorporated robots/cobots (collaborative robots) and innovative software to enable laminography scanning and data processing of large objects, using low X-ray energy (up to 150 KeV) yet producing high-resolution CT image quality without rotating the object or the X-ray source and detector.
The Omni-NDE system uses an X-ray source on one robot and X-ray detector on the other. “We are offering a kind of industrial evolution of the setup used by your dentist,” explains James Bennett, co-founder and CTO of Omni NDE. “In that system, the X-ray detector is in your mouth and the X-ray source is on an articulated arm that can be positioned where needed. In our system, both the source and detector are on programmable robots, so you can now automate positioning, as well as path programming for easily repeatable scans. Even when customers simply use the robots/cobots for easier manual positioning of the source and detector or semi-autonomous movement, they are seeing time savings of up to 80%.”
This arrangement, further enabled by special programming, enables inspection of complicated shapes and 360-degree inspections around a joint or weld, for example. “Previously, your choice in robots were large arms that have been developed mainly for repetitive tasks in automobile assembly,” he continues. “Our solution is to use smaller robots and cobots that are industrial enough to carry a wide range of X-ray sources and detectors but are also much more accurate. For example, cobots have to know their position in order to work alongside humans. We take advantage of this to improve scanning ease of use as well as inspection capabilities. We also have ways to achieve this with more typical robot arms.”
Better resolution
“Robot CT is already comparable to conventional CT and even micro-CT (which provides much higher resolution) in terms of scanning time,” says Bennett. “But now we’ve made it comparable in terms of the image results and resolution by using more sophisticated reconstruction. We’ve performed tests using phantom IQI standards demonstrating resolution down to 25 microns.
Large, complex parts
“We can also get medium-high resolution CT results on large parts,” notes Bennett. “Currently, there is no other way to do this. Until now, the high resolution of micro-CT has been possible only on small parts and inside cabinet systems. Also, odd-shaped parts have typically been difficult to image because when you go to rotate these, you have to move the X-ray source out of the way to prevent collision. That then reduces your resolution and ability to see what you need to.”
“With our system, we can get high-resolution CT results without spinning,” says Bennett, “and the part size or shape no longer matters because the robots/cobots move around the part. Also, parts that couldn’t be scanned in a CT cabinet can now be scanned and with a micro-CT level of resolution. This enables more detailed inspections and analyses of critical parts that were previously impossible.”
“It also means scanning can be done in the field,” he adds. “Cobots can be mounted onto wheeled or motorized bases. Traditional CT systems could never be easily moved to the aircraft hangar or rocket bay. This use of robots/cobots also enables relatively fast initial scans and reconstructions to identify potential areas of interest, followed by longer and more detailed scans only in localized areas, which dramatically reduces inspection times compared to scanning and reconstructing the entire part.”
Multiple modalities, overlay of data
Another revolutionary capability is scanning of the same part using different modalities — e.g., ultrasound, thermography, shearography — in addition to CT to enable new insights using the same robot arms. “Our system then enables overlaying these different data sets and mapping that onto the 3D part,” says Scott Nichols, CEO of Omni NDE. “This allows different defects to be found and seen on the part without sending it to different labs or companies. Also, the ability to see various defects at the same time can enable a better understanding of where and why defects may have occurred, or where failure points are.”
Enabling software
The software Omni NDE has developed to control the robots enables scanning along arbitrary paths. Nichols notes, this means that large, complex, and curved shapes can be scanned with various sensors via a single, adaptable interface — it does not require hours to program. “Further, we’ve developed the software to make our system even more intuitive and easy to use,” says Bennett. “This is why we spend time with our customers in their scanning labs, learning more about what they need to do and also what they want to do but can’t. We then take that information and continue refining both our robot capabilities but also our software and how the whole system is integrated to better meet today’s complex NDT needs.”
Improved efficiency, lower costs
Cobot/robot-based systems also provide a cascade of lower costs, including lower robot cost, lower power source requirements, lower cost X-ray source, and lower infrastructure costs. Because the robots are small and/or mobile, there is no need for a significant foundation to place the robots, and the low power X-ray means that a large and expensive vault is not required for scanning. The design of Omni NDE’s system then takes this further, enabling more effective scans in a shorter period of time. “This lets our customers increase their throughput and output,” says Nichols, “including different types of analyses, made possible by the ability to use other sensors with the same cobots and software. So, one investment, multiple modalities, improved operations and visibility into numerous types of parts and assemblies. This all feeds directly into lower total CAPEX and OPEX costs for the system and the customers, internal or external.”
“We’re able to do things you just can’t do with traditional CT systems,” says Bennett. “And we’re only at the beginning of what this technology can do.”
