In the CAD model on the left, the embedded sphere disappears. If the correct conditions are not used, the embedded sphere prints a void as shown in the CAD model on the right. (Source: NYU Tandon School of Engineering)The market for additive manufacturing, more commonly referred to as 3-D printing, is set to grow nearly 26 percent this year to more than $5 billion, according to research firm Wohlers Associates.
Yet despite this booming market for additive manufacturing, the process still generally relies on shared computer aided design (CAD) files within either an organization or in the cloud. This leaves the design vulnerable to hackers and thieves looking to grab a design file to produce counterfeit parts.
Researchers at NYU Tandon School of Engineering have discovered a way for manufacturers to protect their designs by deliberately embedding hidden flaws in CAD files to thwart this property theft. The induced defects can disappear when the part is printed under a certain set of specific conditions. Those without the information needed to process the files would print a part with undesired defects and lower quality.
How It Is Done
Researchers first translated the CAD design into a stereo-lithography (STL) file format that maps the objects and the internal and external features such as triangles and vectors. Then the researchers explored other aspects of CAD-to-printer processing, such as STL file resolution, printing direction and printer resolution activated or neutralized the intentionally embedded flaws.
The team then developed security features that range from the induction of voids in a part that is supposed to be solid, to features that make the part print in sections that break apart easily.
“The range of security feature designs demonstrated in this work can provide great flexibility to application engineers in terms of how to disguise these flaws easily in a complex shaped part,” says Fei Chen, a doctoral student at NYU Tandon. “Most industrial components manufactured using 3D printing have complex designs to justify the use of 3D printing, which further helps in embedding these features without detection.”
The deliberate flaws can work for both two-dimensional objects and three-dimensional shapes with the hidden flaw inside the part. One CAD model appears to have a sphere inside a rectangular block but it prints without the spherical feature if the processing is conducted under the correct set of parameters. If incorrect processing is used, it creates a void in the block.
The complete study can be found in the journal Materials & Design.
