A team of researchers from Purdue University has developed a 3D printing method specifically for processing energetic materials. The technique is not only capable of producing finely detailed parts made out of energetic materials, but it is also reportedly faster, safer and more eco-friendly than existing processes. To take the innovative research project to the next level, the researchers have also launched a faculty-owned startup for the technology called Next Offset Solutions, Inc.
Energetic materials—a class of material that includes explosives, pyrotechnics, propellants and other materials with high chemical energy storage—are traditionally difficult to process due to their high viscosity. Using a conventional extrusion-based 3D printing method, for instance, the clay-like materials would be prone to clogging the nozzle.
The research team, led by Jeffrey Rhoads, a professor at Purdue’s School of Mechanical Engineering and Emre Gunduz, a former research assistant professor at the school, has found a clever workaround to this issue in the form of a vibrating nozzle. More specifically, the 3D printer developed by the team uses high-amplitude ultrasonic vibrations to reduce friction on the nozzle walls, enabling the viscous energetic materials to flow through.
This technique also allows for more precise flow control, which is highly advantageous for printing energetic materials. As Rhoads explains: “We have shown that we can print these energetic materials without voids, which is key. Voids are bad in energetic materials because they typically lead to inconsistent, sometimes catastrophic, burns.”
The 3D printing process developed at Purdue is also a cut above more traditional manufacturing processes for energetics in terms of efficiency. This is mostly due to the fact that the 3D printing technique doesn’t use solvents to lower the materials’ viscosities. “Some of these processes literally use a ton of solvents that we don’t need,” said Rhoads.
In other words, by processing the materials directly, production can be sped up and costs can be lowered. Crucially, the lack of solvents also makes the new process more environmentally friendly than existing methods.
Safety has also been an important focus in developing the AM process—understandable considering the nature of the materials being printed. By enabling remote control of the 3D printing hardware, people do not have to interface directly with the system, making it safer to use.
Circumventing qualification hurdles
Because industries that utilize energetics—such as defense and energy—require extensive qualification processes for new materials, the Purdue research team opted to work with materials that are already qualified by the Departments of Defense and Energy. This means that the process could be implemented without the additional time and costs associated with qualifying new materials.
Though the team’s focus is on printing energetics—which could be used for jet propulsion, for example—it is also exploring other potential avenues for its 3D printing system, including the production of biomedical implants, customized drugs and more.
Next Offset Solutions, Inc.
The startup founded by the Purdue team will further their research and will scale the production of the 3D printers as well as printable energetic materials, such as solid rocket fuels and other propellants and pyrotechnics. The new company will also pursue other R&D, testing and evaluation initiatives for the additive manufacturing of energetic materials.
Rhoads is taking on the role of chief operating officer at Next Offset Solutions while Gunduz is the startup’s chief technology officer. The startup has also appointed Janine J. Rhoads, who served as a senior executive for a midwest-based Fortune 100 corporation, as its president and CEO.
Next Offset Solutions’ 3D printing process has been patented in collaboration with the Purdue Office of Technology Commercialization.