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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.
Source: US Army Research Laboratory
Journal Reference:
Kevin R. Hart, Ryan M. Dunn, Eric D. Wetzel. Tough, Additively Manufactured Structures Fabricated with Dual‐Thermoplastic Filaments, Advanced Engineering Materials (DOI: 10.1002/adem.201901184)
(Score: 2) by Immerman on Thursday August 27 2020, @03:57PM
I don't think that actually improves much though - zig-zaggy layers would be more interlocking to shear forces attempting to slide layers across each other, but that's mostly already not actually a big deal. The big weakness for FFF printed objects is tension forces that try to pull layers apart - and those aren't actually gong to care much about how "rippled" the layers are because they're pulling directly upwards. That's a big part of bending strength as well - push the top of a tower away from you and the far side goes into compression, while the near side goes into tension.
I suppose you might be able to improve inter-layer tensile strength if you rippled adjacent lines in opposite direction for a sort of basketweave pattern, then so long as the lines on the next layer followed exactly the same horizontal path, the ripple on the next layer could alternate between being squirted down between two high ridges from the previous layer, and forming one of the high ridges that the following layer would get squirted between. Then the plastic squirted between ridges would lock in around their curved edges for much stronger inter-layer bonding. Unfortunately, doing that would mean that your layers would have to be laid down in the same horizontal path, rather than in criss-crossing lines, which dramatically decreases the horizontal strength.
What would really be optimal, is if you could deposit fiber in a sort of 3-D woven structure so that every subsequent layer actually crosses under fibers from the one beneath it at regular intervals, so that the finished piece is really one big complicated knot of fiber rather than distinct layers. I suspect though that that would require many print heads doing an ornate dance around each other, and end up being larger and more expensive than more impressive non-fiber 3D-printing technologies. Unless perhaps your if your fiber were actually some sort of carbon-fiber-expoxy blend - that might actually allow for some crazy-strong carbon-composite objects that'd blow current manufacturing techniques out of the water.