ReFilament: PLA Recycler

The ReFilament is broken down into 3 components: the shredder, the extruder, and re-spooling with our main focus and goals being on shredding and extruding.

The shredder is made out of water jetted aluminum housing with steel hex rods holding the blades. The rods are driven by a steel gear train and high torque DC motor. There are around 50 blades that we modeled off of industrial shredders and more common shredders like crosscut paper shredders. Each was water jetted and filed in order to break the PLA into thicker pieces.

The extruder was an aluminum pipe and auger bit with a heated end. The shredded pieces would drop from the shredder into the extruder pipe and be pushed through the pipe. The last 3 inches were heated to 200-230° C with wrapped Nichrome wire and a temperature controller unit. The PLA would then be pushed through the 1.75 mm hole on the pipe cap to output the filament.

The re-spooling is made up of two rollers that sit at the end of the extruder to pull the filament at a constant speed to help maintain a consistent thickness. It also feeds the filament into a tube which goes to the motors directly involved in creating a new spool. This consists of two motors one that moves the filament linearly and the other that rotates the spool itself which creates an even, untangled wrap on the spool.

Unfortunately, due to time constraints, the re-spool was able to be completed but not tested. Once tested, we foresee the system needing adjustments in motor speeds and spacing of the components involved in redirecting the filament. We were also unable to address the inconsistencies in our shredder that caused pieces to not be small enough for the extruder to be able to handle. We plan on adding a perforated sheet just under the blades so that the pieces continue to catch until they are small enough to fall through (similar to a granulator) as well as potentially creating a train of consecutive shredders that progressively create smaller pieces.