Professor Joshua M. Pearce, of the Materials Science and Engineering department at Michigan Technological University (also a regular on these pages) and Aubrey L. Woern, an undergraduate Mechanical Engineering student have created a 3D Printable Polymer Pelletizer Chopper for cost-effective additive manufacturing.
This new invention chops filament into pellets to be used within a fused granular fabrication (FGF) 3D printer. The pelletizer chopper system can also re-extrude the material into a new filament spool for fused filament fabrication (FFF) 3D printing.
3D Printable Polymer Pelletizer Chopper
In Professor Pearce and Woern’s study, an open-source 3D printable pelletizer chopper was created at a cost of $185.03. Within the single and double motor version of the system, several components were fabricated using a Lulzbot TAZ 6. This includes the base and middle section of the pelletizer chopper, the filament driver, and the spool arms.
The complete polymer pelletizer can process both single thermoplastics as well as composites, which is noted as a significant advantage of the invention. This gives the user the freedom to create unique filament blends for specific applications.
Plastic to pellets
This system can also control the particle size of the pellets manufactured by changing the speed. The pellet size is controlled with the by the speed of the motor(s). Furthermore, the recyclable filament is fed through a Ninjaflex gripper wheel into the main assembly, where it is chopped by the Forstner bit driven by the drill motor.
The system has a 0.5 kg/h throughput with one motor, and a 1.0 kg/h throughput with two motors using only 0.24 kWh/kg during the chopping process. Pellets can also be converted into high-tolerance filament in a RepRapable recyclebot, an open-source waste plastic extruder, with an extrusion temperature of 170 ◦C.
Several plastics were tested, including PLA, ABS, coffee-filled PLA, PP, PETg, and NinjaFlex. Nevertheless, the NinjaFlex was not successful due to its flexibility.
With an open-source design, the researchers believe that the 3D Printable PolymerPelletizer chopper can overcome the common issue of expensive 3D printing filament.
“3-D Printable Polymer Pelletizer Chopper for Fused Granular Fabrication-Based Additive Manufacturing,” is co-authored by Aubrey L. Woern and Joshua M. Pearce.
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Featured image shows the 3D Printable Polymer Pelletizer Chopper. Photo via Michigan Technological University.