Jul 20, 2017 | By Benedict

Researchers at Texas A&M University say they have discovered a way to make 3D printed parts stronger and more useful for real-world applications. The method involves bonding layers of a 3D printed part in a microwave using carbon nanotube-polymer composites.

For most 3D printer users, microwaves are used to warm up pizza pockets between print jobs. But for a group of researchers at Texas A&M University, the wave-generating ovens are playing a much more important role: strengthening the bonds between print layers.

Brandon Sweeney, a doctoral student in Texas A&M’s Department of Materials Science and Engineering, recently teamed up with his advisor, Dr. Micah Green, to develop a new way of strengthening 3D printed parts. The method uses traditional welding concepts, but applies them to the ultra-thin layers of a 3D printed object.

Sweeney’s interest in 3D printing originated in a somewhat unlikely place: the Army Research Laboratory at the Aberdeen Proving Grounds in Maryland, where the doctoral student was previously employed.

“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 recently told his university. “Unfortunately, we always knew those parts were not really strong enough to survive in a real-world application.”

But rather than cause him to move away from additive manufacturing, the failure of certain printed parts was what inspired Sweeney to devote an entire research project to 3D printing.

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

Faced with this apparent dead end, Sweeney entered into a dialogue with Green and Dr. Mohammad Saed, an assistant professor in the electrical and computer engineering department at Texas Tech University.

Together, the trio decided to explore the possibility of using microwaves to weld the layers of 3D printed parts together. Non-microwave ovens would simply melt the plastic of a 3D printed parts, but the researchers thought that microwaves could be used to selectively bond the weaker areas of a 3D printed object while leaving its overall structure intact.

“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 a TIG welder to join the interface of the parts together,” Sweeney explained. “You’re not melting the entire part, just putting the heat where you need it.”

With the help of special material, Sweeney and his team have indeed been able to put the heat where they need it. In their unique process, a thin layer of a carbon nanotube composite is placed on the outside of plastic 3D printing filament, eventually getting “embedded at the interfaces of all the plastic strands” when printed.

When the 3D printed, carbon-infused part is ready, it is placed into a sophisticated microwave oven. Its temperature is then monitored with an infrared camera.

In a research paper documenting the study, Sweeney writes that “microwave irradiation is shown to improve the weld fracture strength by 275%,” a massive increase that the doctoral students thinks will “open up entirely new design spaces for additive manufacturing.”

The technology is licensed by a local company, Essentium Materials, and is awaiting a patent. If they can obtain this patent and commercialize the process, the researchers believe the welding-inspired technology could be used in virtually every industry where 3D printing is involved.

“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,” goaded Sweeney.

The research was recently published in Science Advances under the title “Welding of 3-D Printed Carbon Nanotube-Polymer Composites by Locally Induced Microwave Heating.”



Posted in 3D Printing Application



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