Researchers at Purdue University have successfully 3D printed extremely viscous materials with the consistency of clay and cookie dough.
The development could lead to the creation of other customized ceramics, solid rockets, pharmaceuticals, biomedical implants and other types of food.
"It’s very exciting that we can print materials with consistencies that no one’s been able to print," said Emre Gunduz, assistant research professor in the School of Mechanical Engineering. "We can 3D print different textures of food; biomedical implants, like dental crowns made of ceramics, can be customized. Pharmacies can 3D print personalized drugs, so a person only has to take one pill, instead of 10."
The team was able to accomplish this by applying high-amplitude ultrasonic vibrations to the nozzle of the 3D printer itself, whereas previous solutions have researched the composition of the materials.
"We found that by vibrating the nozzle in a very specific way, we can reduce the friction on the nozzle walls, and the material just snakes through," Gunduz said.
Researchers were able to print items with 100-micron precision while maintaining high print rates. Because most 3D printing uses thermoplastic extrusion it is acceptable for prototypes, but when it comes to actual fabrication, ceramics or metal composites are generally better materials. However, the precursors for these materials are extremely viscous and normal 3D printers can’t deposit them because they can’t be pushed through a small nozzle, researchers said.
"Solid propellants start out very viscous, like the consistency of cookie dough," said Monique McClain, a Ph.D. candidate in Purdue's School of Aeronautics and Astronautics. "It’s very difficult to print because it cures over time, and it’s also very sensitive to temperature. But with this method, we were actually able to print strands of solid propellant that burned comparably to traditionally cast methods."
The first practical application being explored by the team is solid rocket fuel. This material offers the opportunity to customize the geometry of a rocket and modify its combustion, allowing certain parts to burn faster or slower.
The full research can be found in the journal Additive Manufacturing.