Researchers develop new method for strengthening 3D printed parts

As more and more parts are manufactured using 3D printing, researchers are looking for ways to ensure they are strong and useful in real-world applications.

A doctoral student at Texas A&M University has developed a method that ensures 3D printed parts are 275% stronger.

Brandon Sweeney and a colleague working in the lab.

Brandon Sweeney, a student in the Department of Materials Science and Engineering, and his advisor Dr. Micah Green applied the traditional welding concepts and a carbon nanotube composite filament to bond the submillimeter layers in a 3D printed part together with focused microwaves.

It was while he was employed at the Army Research Laboratory at the Aberdeen Proving Grounds in Maryland that Sweeney really began working with 3D printed materials

“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 parts were not really strong enough to survive in a real-world application.”

3D printed objects often suffer from fracturing, limiting durability and reliability of parts.

“I knew that nearly the entire industry was facing this problem,” Sweeney said. “Currently, prototype parts can be 3-D printed to see if something will fit in a certain design, but they cannot actually be used for a purpose beyond that.”

Sweeney collaborated with Green in the Department of Chemical Engineering at Texas Tech University, who had been working with Dr. Mohammad Saed, assistant professor in the electrical and computer engineering department at Texas Tech, on a project to detect carbon nanotubes using microwaves. The trio crafted an idea to use carbon nanotubes in 3D printed parts, coupled with microwave energy to weld the layers of parts together.

3D parts cannot simply be stuck into an oven to weld it together because it is plastic and will melt, explains Sweeney. The team needed to explore different welding methods, borrowing from traditional sources like a torch or TIG welder to join the interface of parts together.

“You’re not melting the entire part, just putting the heat where you need it,” Sweeney adds.

Since the layers making up the 3-D printed parts are so tiny, special materials are utilized to control where the heat hits and bonds the layers together.

“What we do is take 3-D printer filament and put a thin layer of our material, a carbon nanotube composite, on the outside,” Sweeney said. “When you print the parts out, that thin layer gets embedded at the interfaces of all the plastic strands. Then we stick it in a microwave, we use a bit more of a sophisticated microwave oven in this research, and monitor the temperature with an infrared camera.”

The technology is patent-pending and licensed with a local company in College Station, Essentium Materials. The materials are produced in-house, where they have also designed a new 3D printer technology to incorporate the electromagnetic welding process into the 3D printer itself. While the part is being printed, they are welding it at the same time. They are currently in beta mode, but this has the potential to be on every industrial and consumer 3D printer where strong parts are needed.

“If you’re an engineer and if you actually care about the mechanical properties of what you’re making, then this ideally would be on every printer in that category,” Sweeney said.

The team recently published a paper “Welding of 3-D Printed Carbon Nanotube-Polymer Composites by Locally Induced Microwave Heating,” in Science Advances.

 engineering.tamu.edu