Texas A&M engineers and additive manufacturing solutions provider Essentium, Inc. have developed a new way to more effectively weld adjacent 3D printed layers together.
The new technology could help remedy a major flaw in 3D printing – mechanically weak parts caused by the imperfect bonding between the individual printed layers.
The scientists have successfully integrated plasma science and carbon nanotube (CNT) technology into standard 3D printing to weld adjacent printed layers more effectively, increasing the overall reliability of the final part.
Plastics are commonly used for extrusion 3D printing, known technically as fused-deposition modeling.
In this technique, molten plastic is squeezed out of a nozzle that prints parts layer by layer. As the printed layers cool, they fuse to one another to create the final 3D part.
Studies however show that these layers join imperfectly; printed parts are weaker than identical parts made by injection molding where melted plastics simply assume the shape of a preset mold upon cooling.
To join these interfaces more thoroughly, additional heating is required, but heating printed parts using something akin to an oven has a major drawback.
“If you put something in an oven, it’s going to heat everything, so a 3D-printed part can warp and melt, losing its shape,” says associate professor Micah Green.
“What we really needed was some way to heat only the interfaces between printed layers and not the whole part.”
To promote inter-layer bonding, the team turned to carbon nanotube coatings.
Similar to the heating effect of microwaves on food, the team found that these carbon nanotube coatings can be heated using electric currents, allowing the printed layers to bond together.
To apply electricity as the object is being printed, the currents must overcome a tiny space of air between the printhead and the 3D part. This is where plasma comes into the picture.
The team collaborated with associate professor David Staack to generate a plasma that could carry an electrical charge to the surface of the printed part.
This technique allows electric currents to pass through the printed part, heating the nanotubes and welding the layers together.
Image and content: Essentium/Texas A&M University
