Brandon Sweeney, who began working with 3D printed materials in the army, and Dr Micah Green applied traditional welding concepts and carbon nanotube composites to bond the submillimetre layers in a 3D printed part together, while in a microwave.
“The basic idea is that a 3D part cannot simply be stuck into an oven to weld it together because it is plastic and will melt,” Sweeney explained. “We realised 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. You're not melting the entire part, just putting the heat where you need it.”
Since the layers making up the parts are so tiny, special materials are utilised to control where the heat hits and bonds the layers together.
"What we do is take 3D 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 process is currently in beta mode, but according to Sweeney, has the potential to be on every industrial and consumer 3D printer where strong parts are needed.