A new type of multi-polymer filament has been developed for commonly used desktop 3D printers that could save money and facilitate fast printing of critical parts at the point of need. Parts produced with these printers historically have had poor strength and toughness, which prevented affordable printers from being used to resupply parts on demand. The new material allows low-cost printers to create parts that, once subjected to a few hours of heat, can achieve mechanical properties robust enough to withstand the rigors of field operations.
The Army would like to be able to print parts in the field to simplify logistics by carrying digital part files instead of physical parts but to date, the technologies for producing high-strength parts have not been practical in an expeditionary setting. These printers are too large, energy-hungry, delicate, or messy and their feedstocks can require specialized storage requirements.
Fused filament fabrication (FFF) is the most common additive manufacturing technology but parts fabricated using FFF lack sufficient mechanical integrity for most engineering applications. The research team used a novel thermal draw process to fabricate a dual-material filament comprising acrylonitrile butadiene styrene (ABS) with a star-shaped polycarbonate core. This dual-material filament is then used as feedstock in a conventional FFF printer to create 3D solid bodies with a composite ABS/polycarbonate core meso-structure. This novel filament can allow low-cost printers to produce parts with mechanical properties competitive with injection molded plastics.
The research team is experimenting with new material pairings, print conditions, and annealing protocols to further improve mechanical properties and reduce processing times. Their goal is to reduce current annealing times of 24-48 hours to four hours or less.
Having the option to additively manufacture parts from a high-strength polymer via the FFF process can provide the ability to produce better temporary parts much quicker — hours versus days or weeks — and at significantly lower cost.