Description: TUI proposes a novel process to produce 3d printer feedstock filament out of scrap ABS on the ISS. Currently the plastic filament materials that most 3d printers use are produced with screw-based extruders that are fundamentally designed for high volume terrestrial production from uniformly pelletized resin feedstock. These require relatively large continuous batch sizes with significant operator inputs and have generally poor control over the produced filament geometry. Existing extrusion machines also tend to rely on separate facilities for fully drying the material beforehand, and do not inherently provide tight flow-rate control. The proposed effort will develop a filament extruding machine that uses a process called Positrusion that is designed from the ground up for optimally producing small batches of positively controlled round filament directly out of arbitrarily shaped scraps of ABS plastic, while meeting requirements for operation on the ISS. The machine will accept miscellaneous ABS parts, it will dry and degas the input material before melting and extruding it through a die, and the cross-sectional dimensions and feed-rate of the cooling extrudate will be tightly controlled in a continuous analog of closed-die molding.

Benefits: By enabling reclamation of materials used by NASA's on-orbit 3d printing facilities, this effort will minimize the requirements for resupplying and/or storing excess feedstock for orbital and deep space missions that utilize 3D printing for replacement parts, unforeseen needs, and planned sequential repurposing of components for progressive phases of a given mission. The proposed effort supports the "In-Space Assembly, Fabrication and Repair" technical need identified in NASA Technology Roadmap 2012 TA12; WBS 2.4.1.d.

This novel process that is fundamentally better suited for reclaiming scrap material on the ISS will also be ideal for private consumers and professional users to recycle scraps from many commercial 3d printers. Several small companies have advertised bench-top extruder machines for making filament, some even being designed to recycle scraps, but all of those we are aware of are emulations of the traditional industrial process and are not sufficiently reliable for the average user. The Positrusion process would not be suited for high through-put industrial purposes, but it will be marketable to a large portion of the growing population of household and workplace 3d printer users to enable individuals to efficiently practice a self-sustaining 3D printer material cycle.