NASA is developing a sustainable in-space manufacturing ecosystem by providing both the capability to create 3D printer filament from currently used packaging material as well as the development of new, high-performance packaging architectures created with materials that are well suited for use in 3D printing. NASA’s in-space manufacturing program supports Earth-based technology development to enable technologies and research on the International Space Station (ISS) and for deep space missions. In 2014, a 3D printer was installed and used successfully on the ISS, creating the first additively manufactured part in space. While additive manufacturing is a game-changing technology for in-space repairs and part formation, it still requires a plastic feedstock material to fabricate the printed parts. Without a recycling capability, long-duration and long-distance missions would require a large supply of feedstock that would either need to be stored onboard, taking up both mass and cargo space, or delivered in expensive resupply missions to enable the continued usage of the 3D printer.
In order to minimize the amount of plastic that must be stored for 3D printing, as well as mitigate the waste generated when the 3D printed part is used, there is a need for the installation of a plastic recycling capability on the ISS. Plastics recycling will enable in-space production of 3D printer filament from old 3D printed parts. For the ISS, this facility will provide significant launch savings by reducing or removing the launch payload required to restock ISS printers as well as reduce the waste mass that must be deorbited by cargo vehicles. For deep space missions, the presence of a recycling facility will reduce the amount of stored mass and cargo space. Positrusion™ recycling technology accepts scrap plastic parts and other plastic waste materials to fabricate high-quality, 3D-printer-ready feedstock to enable on-orbit manufacture of tools, containers, radiation shielding, and mechanical parts.
A two-pronged approach was taken to develop 3D printer filament from packaging material. First, the recyclability of polyethylene Ziploc® bags into 3D printer filament using Positrusion was studied. Positrusion was built to be compatible with all printable plastics, and while polyethylene is not a widely used 3D printer material, the processing capabilities of Positrusion enabled the creation of high-quality 3D printer filament from Ziploc bags. Tensile bars for mechanical property testing were printed to measure the impact of the recycling process on the properties of the printed material. The impact of the 3D printer used for printing was tested by studying tensile bars made with different nozzles and printers. Both the recycling process and the 3D printing process result in materials degradation in the printed plastic.
Next, alternative packaging methods were developed that utilize materials better suited for 3D printing. A system of fabricating and sealing monomaterial bags out of ABS, PEEK, and Ultem was developed. Most importantly, a series of custom 3D printer infills with varying flexing and bending directions was developed. When these infills are utilized as the backbone for 3D-printed packaging, the 3D-printed packaging technology has been demonstrated to have superior vibration attenuation capabilities compared to a volumetrically equivalent amount of NASA-utilized packaging foam. In addition, the 3D-printed packaging material can be recycled into 3D printer filament while the foam cannot. Therefore, replacing packaging foam with the 3D printed packaging technology will provide high-quality material for conversion into 3D printer filament on NASA missions and, eventually, for terrestrial 3D printer users as well.