Brandon Sweeney, a doctoral student at Texas A&M University's Department of Chemical Engineering, has developed a way to make 3D printed parts 275 times stronger. Sweeney, working with his adviser Micah Green, associate professor of chemical engineering, applied traditional welding concepts and a carbon nanotube composite filament to bond the submillimeter layers in a 3D printing part using focused microwaves.
Sweeney began working with materials for 3D printing while he was employed at the Army Research Laboratory at the Aberdeen Proving Grounds in Maryland.
“I was able to see the amazing potential of the technology, such as the way it sped up our manufacturing times and enabled our CAD designs to come to life in a matter of hours,” Sweeney said. “Unfortunately, we always knew those were not really strong enough to survive in a real-world application.”
When he started his doctorate studies, Sweeney was working with Green in the chemical engineering department. Green had been collaborating with Mohammad Saed, assistant professor in the electrical and computer engineering department at Texas Tech, on a project to detect carbon nanotubes using microwaves.
The three men came up with an idea to use carbon nanotubes in 3D printed parts, then using microwave energy to weld the layers of parts together.
“The basic idea is that a 3D part cannot simply be stuck in an oven to weld it together, because it is plastic and will melt,” Sweeney said. “We realized that we needed to borrow from the concepts that are traditionally used for welding parts together where you'd use a point source of heat, like a torch or TIP welder, to join the interface of the parts together. You're not melting the entire part, just putting the heat where you need it.”
The team puts a 3D printed filament and apply a thin layer of a carbon nanotube composite on the outside.
“When you print the parts out, that thin layer gets embedded at the interface of all the plastic strands,” Sweeney said. “Then we stick it in a microwave, we use a big more sophisticated microwave oven in this research, and monitor the temperature with an infrared camera.”
The patent-pending technology is licensed with a local company, Essentium Materials LLC. That firm has developed a new 3D printer technology that incorporates the electromagnetic welding process into the printer itself, so while parts are getting printed, then are welding it at the same time.