Embedding hidden information in additively manufactured metals

Counterfeiting is one of the most significant problems in the global product market. Indeed, ensuring manufactured goods and components have not been copied and replaced illegally by counterfeited goods is a high-priority concern of the manufacturing and defense industries in the U.S. and around the world. A potential solution would hold wide-reaching impacts and implications in various areas ranging from enhancing biomedical implants to protecting national defense assets.

Novel additive manufacturing (AM) technologies are not exempt from potential counterfeit-related issues. AM technologies are revolutionizing the manufacturing industries thanks to their capability of producing near-net-shape metallic parts with complex geometries inaccessible to traditional production techniques.

In addition, AM fabricated parts can achieve a large material complexity given the fine control of the AM process parameters permitting for localized control of basic material properties, like chemical composition, crystalline phase, microstructure, or crystallographic texture. This capability makes the design of materials with local or gradual changes in their functional properties, such as strength, magnetism or shape memory effect, possible

Ensuring security and reliable authentication in manufacturing is a critical national concern, with the U.S. investing billions of dollars in manufacturing. Without such a method readily available, it can be nearly impossible to differentiate an authentic part or component from its counterfeit copy.

Texas A&M University researchers have developed a method of imprinting a hidden magnetic tag, encoded with authentication information, within manufactured hardware during the part fabrication process. The revolutionary process holds the potential to expose counterfeit goods more easily by replacing physical tags such as barcodes or quick response (QR) code with these hidden magnetic tags, which serve as permanent and unique identifiers. The team recently published its research in the journal Additive Manufacturing.

The research team implemented metal additive manufacturing techniques to accomplish its goal of successfully embedding readable magnetic tags into metal parts without compromising on performance or longevity. Researchers used 3D printing to embed these magnetic tags below the surface into nonmagnetic steel hardware. Other applications for this method include traceability, quality control and more, largely depending on the industry in which it is used. Once embedded into a nonmagnetic item, the magnetic tag is readable using a magnetic sensor device such as a smartphone by scanning near the correct location on the product, allowing the designated information to be accessed by the user. While other methods exist for imprinting information, they primarily require sophisticated and costly equipment that introduces a barrier to real-world implementation.

According to the authors L-DED is a suitable fabrication method to produce these magnetic tags since it enables the combination of powders with distinct chemical composition and functional properties. Although fabrication of composites with locally controlled magnetic behavior is possible via dependence of deposited material composition on printing parameters, multipowder techniques like L-DED may be the only option for many alloy systems. Layer thickness and hatch distance is typically larger in L-DED than in L-PBF technologies, which may impose a larger minimum size for the magnetic physical tag, although sensor probe resolution and tag depth might end up being more restrictive than track dimensions. The authors created a custom three-axis magnetic sensor capable of mapping the surface and revealing the regions where the embedded magnetic tag was accessible. While the system is more secure than a physical tag or code located on the exterior of an item, the team is still working to improve the complexity of the method’s security.

As the project continues, lead author Professor Karaman explained the next steps include developing a more secure method of reading the information, possibly through the implementation of a physical “dual-authentication” requiring the user to apply a specific treatment or stimulus to unlock access to the magnetic tag.