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Non-destructive testing and validation for additive manufacture
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Non-Destructive Testing

Additive Manufacturing Symposium 2017

TWI has been at the cutting edge of non-destructive testing (NDT) technology for decades and in recent years has successfully applied this expertise to the inspection of additively manufactured parts.

With more than 50 engineers and technicians devoted to the practice and development of more than a dozen advanced NDT techniques, we can advise you on the most effective testing method for any combination of component material and geometry.

We have worked with companies across industry to inspect parts created using additive manufacturing (AM) – both on completed builds and in real time during the AM process.

Whether you want to complete NDT in-house and require guidance with technique selection and training, or you would like us to provide a complete inspection service on your behalf, our combination of experience, expertise and equipment means we can help.

We currently primarily use two NDT methods for inspecting AM parts: X-ray computed tomography (CT) and digital radiography (DR). Our workshops contain extensive facilities for both systems and, more importantly, we possess the skill to get the most out of each technology.

X-ray computed tomography

X-ray computed tomography is a powerful NDT technique capable of producing volumetric three-dimensional density data of a scanned part at resolutions down to 15µm. Using this method we can generate cross-sections of AM components that reveal the internal structure in fine detail.

This enables us to identify any voids, inclusions, cracks and residual powder deposits in places that would be impossible to inspect visually. We can also check for consistent wall thickness and make sure the fill volume of lattice-structured components is satisfactory.

Data generated using CT can be exported and mapped to a CAD model of the part, allowing detailed analysis using numerical modelling. We can use all of this information to refine design and manufacturing parameters for AM parts, ensuring your component conforms to its design specification.

Digital radiography

While CT generates detailed three-dimensional models showing the internal makeup of a part, it can require significant time to complete. Although TWI is researching ways to introduce it into the AM production process, it is currently almost exclusively used for inspecting completed AM parts.

Digital radiography, by contrast, is a very fast technique capable of producing results in real time, meaning it can be applied in-line in a production environment to automatically detect defects in specific regions of interest and in AM components as they are made. It produces a two-dimensional rendering of the density and material thickness of uniformly shaped regions of interest – providing an effective method of quality control on an AM production line.

Other techniques

In addition to CT and DR, we are researching various in-situ inspection techniques based on optics, ultrasound and laser ultrasound to identify material defects of AM metallic parts during the build process.

By developing effective methods of performing inspection in real time, as the part is manufactured, we can reduce the need for testing once it is complete.

Contact us for more information or to find out how we can help your business.