Microwaves and nanotubes make for stronger 3D-printed objects

Brandon Sweeney places a 3D-printed item in the microwave source (Credit: Texas A&M University)

Valuable as 3D printers are proving to be for tasks such as prototyping, the objects that they create still tend to not be as strong as their traditionally-constructed counterparts.

That’s because printed objects are made up of individual layers of material, as opposed to one solid chunk.

Thanks to research being conducted at Texas A&M University, however, 3D-printed items can now be made that are reportedly 275 percent stronger than would otherwise be possible.

Doctoral student Brandon Sweeney and his advisor Dr. Micah Green developed a new technique, that involves depositing a layer of carbon nanotubes on the outside of a plastic filament used for 3D printing.

That filament is then used in a regular printer, for creating an object in the usual fashion – by laying down sequential layers of softened plastic, produced by heating and extruding that filament.

Once the printing process is complete, the object is placed in a solid state microwave source (basically a specialized microwave oven).

The heat that is generated gets concentrated in the carbon nanotubes, causing the plastic in those areas only to melt and blend with the surrounding plastic. In this way, the plastic gets selectively welded together at the boundaries between the layers.

“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,” says Sweeney.

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

The technology has been licensed to local startup company Essentium Materials, which plans to commercialize it.

It is hoped that the microwave system could be built right into printers, so the printing and electromagnetic welding could take place in the same machine, in one step.

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