The Case Study | Issue 5 | Identifying flaws in complex 3D printed metal parts

Theta Technologies Limited are world leaders in a unique and cost-effective non-destructive testing technology designed specifically to cope with the complex nature of additive manufactured metal parts. Based in Exeter, UK, Theta Technologies has developed the world’s first commercial nonlinear resonance NDT product that offers manufacturers a more cost-effective, rapid non-destructive testing solution that other NDT techniques.

CONTACT US

Theta Technologies Limited

3 Babbage Way Exeter Science Park

Clyst Honiton Exeter

United Kingdom

EX5 2FN

Website: www.thetandt.com

Email: info@thetandt.com

CONNECT WITH US

Theta Technologies Limited

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Editor’s Note

We are pleased to present our latest issue of ‘The Case Study’. This issue is dedicated to examining the intricate challenges involved in the non-destructive testing (NDT) of complex 3D printed metal designs and how Theta Technologies’ nonlinear resonance inspection technology can be used to solve existing NDT challenges in additive manufacturing. As 3D printing continues to revolutionise the manufacturing industry, it is crucial to address the unique testing hurdles associated with this rapidly advancing technology.

Three-dimensional printing has opened up a realm of possibilities for engineers and designers, enabling the creation of intricate and customised metal components that were once thought unattainable. However, the complexity inherent in these designs poses significant challenges when it comes to ensuring their structural integrity and quality. Read on to find out how nonlinear resonance has been used to test notoriously complex heat exchanger components for signs of detrimental flaws. Enjoy!

Chris Parker, Editor

ISSUE #4

READ THE PREVIOUS ISSUE

USING COMPLEMENTARY NDT TECHNIQUES TO DETECT A WIDER RANGE OF FLAWS

ADDITIVE ADDITIVE MANUFACTURING

ADDITIVE ADDITIVE ADDITIVE ADDITIVE

ADDRESSING THE CHALLENGES OF NON-DESTRUCTIVE TESTING

IN COMPLEX DESIGNS

MANUFACTURING

Metal additive manufacturing (AM), also known as 3D printing, has emerged as a transformative technology in the manufacturing industry

It offers unprecedented design freedom, enabling the production of complex geometries that were previously unattainable through conventional manufacturing processes. Despite the overwhelming benefits, metal AM possesses unique challenges for non-destructive testing (NDT) methods. These challenges have meant that many manufacturers have simply not been able to utilise the technology to its full potential.

Complex geometries and internal structures

One key advantage of metal AM is the ability to fabricate intricate designs and complex internal structures. While this offers exciting possibilities, it also presents significant difficulties in quality assurance. Traditional NDT techniques, such as Ultrasound or Dye Penetrant often rely on parts being solid and having smooth surfaces. In AM-produced components however, the geometries are often irregular, convoluted, and possess internal channels and voids, making it challenging for conventional NDT methods to effectively probe those areas. Even X-ray CT, the current ‘gold standard’, struggles to produce acceptable images of larger, dense metal parts with fine internal detail.

Limited accessibility

Another inherent challenge is the limited accessibility of internal structures in increasingly complex AM geometries. Due to the layer-by-layer fabrication process, certain areas of the part are often inaccessible or require disassembly to perform effective NDT inspections; eradicating the non-destructive aspect. This is a considerable hurdle for those who need to assess the quality and integrity of hidden regions, consequently, the application of standard NDT techniques becomes impractical or infeasible.

Material variability and anisotropy

Metal AM processes introduce unique material characteristics that further complicate NDT practices. Variability in material properties such as, porosity, grain structure, and residual stresses can arise due to inherent process complexities. The anisotropic nature of the AM parts, resulting from directional solidification and layering effects, poses additional challenges for NDT. These factors can significantly affect the reliability and accuracy of NDT results as the established models and methodologies for conventional materials may not directly apply to AM-produced components.

NEXT LEVEL FLAW DETECTION

If you’ve been looking to adopt metal additive manufacturing for end-user parts only to have that ambition thwarted by the lack of effective non-destructive testing for increasingly complex parts, then Theta Technologies revolutionary technique could almost certainly be the solution to your problems.

The unique nonlinear resonance technique developed by Theta Technologies is designed to excite components using a variety of different sources. Once the component is excited, a detector system watches for non-linearity within the component under test. With the metal additive manufacturing industry rapidly evolving, the lack of an effective non-destructive testing solution with the ability to cope with the plethora of design opportunities associated with 3D printing has caused frustration amongst designers and manufacturers alike. It is because of this that additive manufacturing has largely been adopted for prototyping rather than end-user parts. Enter Theta Technologies!

Theta’s unique nonlinear resonance non-destructive testing technique could not be emerging at a better time for those wanting to additive manufacture bespoke metal parts; particularly for safety-critical applications. Theta’s solution offers a number of crucial benefits over other existing NDT options on the market such as saving time, reducing overall costs and freeing up resources by identifying flawed components before costly post-processing practices are undertaken.

Continued on page 6

A game-changing non-destructive testing solution proven to detect the presence of flaws in complex AM metal parts.

Theta’s solution offers a number of crucial benefits over other existing NDT options on the market...

THE CHOICE

ON PLATFORM TESTING

Our unique nonlinear resonance technology allows you to perform a non-destructive test of your AM metal part immediately after printing. This helps you identify any issues with the print prior to undertaking any costly post-processing steps.

IS YOURS

PLATFORM TESTING

OFF

Would you prefer to test your 3D-printed metal parts without the build plate? The choice is yours! Our non-destructive testing technology gives you both options and can be performed at multiple stages in your production workflow.

PROOF the

Validating the credentials of nonlinear resonance NDT

There is, of course, no better way to prove that a new technology does what it claims to than by putting it under intense scrutiny. That’s where components such as heat exchangers come in. The notoriously complex geometry of these parts has meant that existing non-destructive testing technologies have been far from effective at identifying flaws within the parts; so it was time for Theta Technologies to prove that they had the solution to an increasingly common additive manufacturing problem.

Theta Technologies’ nonlinear resonance non-destructive testing technology was used to assess two additive manufactured heat exchanger samples as part of the study. Using nonlinear resonance to excite each component into resonance, Theta Technologies were able to exploit microscopic flaw behaviours to identify whether either of the samples showed signs of a flaw within their complex structures. By increasing the excitation of the parts, Theta Technologies are able to identify whether the part is flawed, as defective samples show an amplitude dependent frequency response. In this case, a nonlinear signature could be an indicator of cracking.

No Flaw

Additive manufactured components are excited using a variety of different sources. A consistent signature between low and high amplitude excitations identifies a good part.

Flawed

By increasing the energy of the excitation of a metal component, it is clear to see whether the signature changes. A variation in signature indicates that there is a flaw within the part.

Theta Technologies were able to exploit microscopic flaw behaviour to identify whether either of the samples showed signs of flaws...

The difference

Clear distinctions are made between flawless and flawed samples.

Problem solved

The manufacturers of the heat exchangers were already aware that one of the samples contained flaws and subsequently challenged Theta Technologies’ nonlinear resonance NDT technique to provide a successful identification of these known defects. The blind tests of each of the Inconel samples were undertaken using the same parameters, with repeatability and reproducibility of the part examinations a key feature in determining the overall outcome.

The graph above shows the ‘Damage Index’ for each of the samples subjected to the tests, S8 and S9. The error bars show two standard deviations obtained in multiple reproducibility tests. The results showed clear distinctions between the flawed and flawless component based on the nonlinear signature, thus proving Theta Technologies’ credentials in identifying flaws in complex additively manufactured components.

ABOUT US

Theta Technologies Limited is a UK-based engineering company specialising in the non-destructive testing of metal and composite parts produced for critical applications. Our unique nonlinear resonance technology enhances the efficiency of metal additive manufacturing processes, enabling more costeffective, safer and rapid flaw detection solutions than other NDT techniques..

CONNECT WITH US

Theta Technologies Limited

3 Babbage Way Exeter Science Park

Clyst Honiton Exeter

United Kingdom EX5 2FN

Website: www.thetandt.com

Email: info@thetandt.com

Theta Technologies Limited

theta_technologies

theta_NDT

Theta Technologies Limited

Theta_Technologies_Limited