Development and Evaluation of a Distributed Recycling System for Making Filaments Reused in Three-Dimensional Printers

Due to an increase in the number of applications for 3D printers, the use of thermoplastic resins such as acrylonitrile butadiene styrene (ABS) and poly lactic acid (PLA), which are typical filament materials for fused filament fabrication (FFF) type 3D printers, has also increased significantly. This trend has produced an interest in recycled filaments, both to reduce the manufacturing cost of fabricated products and to lower greenhouse gas emissions. Also, this recycling system is very useful to make functional filament such as highly conducting or high strength filament by combining carbon nanotube or polydopamine during recycling process. This study presents the design procedures of system for making recycled filaments for 3D printers from waste polymer. The system integrates four main parts for recycling filament: a shredder, which crushes polymer waste into small pieces; an extruder, which extrudes filament from the crushed pieces; a sensing and control component, which regulates the diameter of the extruded filament via a closed-loop control system, and a spooler. Additionally, the dimensional accuracy, the mechanical strength of pristine, and recycled filaments were investigated and compared.