High-frequency Ultrasonic Detection of Security Markers in Metal Additive Manufacturing Components

Embedding security markers in additive manufacturing (AM) components have been investigated as means to ensure product authentication and mitigate risks of counterfeiting and reverse engineering. These security markers have been previously detected using X-ray computed tomography (XCT), which is a method also commonly used for defect detection in AM. Ultrasonic testing (UT) has been used for offline detection of defects in AM, but UT has not been implemented for complex security markers such as QR codes in AM. In this work, high frequency UT (40 MHz) and image processing are used for the first time in successfully detecting QR codes in laser powder bed fusion (LPBF) parts, with feature sizes as low as 0.5 mm. Additionally, UT is also implemented as means to detect lack of fusion and keyhole defects in LPBF, which presents a low-cost alternative to XCT for defect detection.
Significance:
The digital nature of AM supply chains makes it susceptible to cyber- and physical threats, including counterfeit products. There is a need for developing security and traceability markers embedded in products, as well as low-cost non-destructive testing (NDT) methods such as UT for detection of security markers. The high frequency ultrasound systems (71-1 MHz) manufactured by Fujifilm VisualSonics Inc. are well suited for detecting small discontinuities in AM products. With high frequency UT, small security markers can be easily detected in AM components for the purpose of authentication and traceability. The high-frequency linear array ultrasound transducer (40 MHz, 40 µm resolution) is expected to have superior resolution for this application compared to conventional commercial phased array UT (10 MHz). This presentation showcases R&D efforts undertaken by MSAM (University of Waterloo) and Fujifilm VisualSonics Inc. to integrate security markers in AM parts and test their readability for a low alloy steel material used for automotive applications.