Forensic Tracking for 3D-Printed Parts
A study published in the journal Forensic Science International reports that researchers from Curtin University in Perth, Australia, have developed a forensic method to analyze 3D-printed PLA parts and match them to their respective filament, correctly matching 26 out of 28 samples of PLA. This potentially provides a way to link seized 3D-printed firearms with other seized filament, allowing police to form a clearer network for the manufacturing and distribution of the printed items.
3D-printed firearms have become a significant challenge worldwide as they lack traditional serial numbers or registration records. Easily manufacturable and disposable plastic firearms present a distinct investigative hurdle for law enforcement agencies.
However, this research, conducted by Dr. Georgina Sauzier and colleagues from Curtin University's School of Molecular and Life Sciences alongside forensics experts from ChemCentre, has devised a way to trace a printed object to a specific filament product, down to the brand and type.
Thermal Analysis and Material Properties
The process of 3D printing changes the filament’s physical properties, and this change can be measured. In this research, differential scanning calorimetry (DSC) is used, a thermoanalytical technique that lets the sample go through a range of temperatures, and the instrument measures how heat flows through the sample. It measures how much energy or power is used to keep the sample at a certain temperature or to change its temperature, giving a graph of its thermal properties.
The sample’s thermal properties can then be cross-referenced with unprinted filament, creating an association between them. As of now, the tested PLA products are the only successfully identified material, with PETG and ABS not providing enough information to link them to their filament product due to their amorphous nature. PLA has a semi-crystalline molecular structure, which provides clearer transition points under temperature tests as the crystalline structures break down and rearrange.
However, ABS and PETG did show some promise when tested using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, which uses infrared light to identify chemical bonds and material composition. The team identified differences in additives using this method, though it still did not provide enough definitive information to trace them back to their specific filament products.
Future Testing and Limitations
The research remains in an early stage requiring more rigorous testing. The team printed using a single machine, utilized small sample tiles, and stored them for a year in monitored office conditions before testing. Material properties can be further altered by varying cooling rates, print speeds, and different hardware configurations.
Despite these limitations, correctly identifying 26 out of 28 samples represents a promising step forward. As the research matures and expands to encompass a broader range of materials, it could potentially help trace illegal 3D-printed weapons to specific printers and filament rolls.
