Military-spec filament produces stronger 3D-printed objects

While consumer-grade 3D printers may be adequate for making things like models or curios, they’re not always up to the task of creating objects that stand up to real-world use. That could be about to change, though, thanks to a new printing filament.

Compact, inexpensive 3D printers typically utilize a process known as fused filament fabrication (FFF). This involves heating a plastic filament to its melting point, then extruding it through a nozzle. Successive layers of the molten plastic are deposited one on top of the other, forming a single solid object as they cool and fuse together.

According to US Army engineers, though, items printed in this fashion tend to be too structurally weak for rough-and-tough use by soldiers in the field. This is a shame, since if troops were able to carry small, cheap 3D printers with them, they could make parts and tools onsite as needed. And although there are printers that use non-FFF techniques to produce stronger objects, those machines are large and costly, making them impractical for field use.

Led by Dr. Eric D. Wetzel, researchers from the Army’s Emerging Composites team set out to address this problem. They ultimately created a new dual-polymer filament that allows consumer 3D printers to produce much stronger items, utilizing their existing FFF hardware.

The material starts out in the form of a cylinder with a star-shaped polycarbonate core, that’s surrounded on all sides by ABS (acrylonitrile butadiene styrene). Utilizing a proprietary device called a thermal draw tower, that cylinder is heated and drawn out into a thin filament.

Once that filament cools, it can be wound onto a reel and then used in an ordinary FFF 3D printer. Objects printed from the material are subsequently heated in an oven and then cooled, ensuring that the two polymers thoroughly fuse together.

In lab tests, such objects proved to be much stronger than those made from conventional filaments – in fact, they exhibited mechanical properties similar to those of identical items produced via commercial injection moulding techniques. The material’s annealing (heating and cooling) time currently sits at 24 to 48 hours, but the team hopes to reduce that figure to four hours or less.

The Army is now looking for industry partners who may be interested in commercializing the technology, for use beyond military applications.

A paper on the filament was recently published in the journal Advanced Engineering Materials.

Source: US Army Research Laboratory

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