Michigan Tech Researchers Publish Paper on New Recyclebot 3D Printer

If you’re familiar with 3D printing, solar power, and open source research, then you’ve probably heard of Dr. Joshua Pearce, Associate Professor of Materials Science & Engineering, and Electrical & Computer Engineering, at Michigan Technological University (Michigan Tech).

Dr. Pearce works to educate the industry as much as he does his students, and has participated in several studies and projects regarding at-home 3D printing, the amount of IP protection in the industry, 3D printers powered by solar energy, metal 3D printing, and RepRap 3D printers, as well as open source software and hardware, among others. He also runs the university’s Open Sustainability Technology (MOST) Research Group.

RepRapable Recyclebot switches.

Dr. Pearce is a major proponent for sustainability, and has also studied filament recycling in the past. In the 2017 study, Dr. Pearce and the rest of his team discussed the development of a solar-powered version of the open source “recyclebot,” an extruder for waste plastic that he designed back in 2013.

It’s expensive to recycle plastic, and also wastes a lot of energy, as it needs to be transported to a central location and separated. The recyclebot could help reduce the energy and cost by collecting plastic waste and recycling it into 3D printer filament on-site.

“As you know 3D printing filament is still sold for far more than plastic pellets and several companies offer filament makers. There has also been some efforts to make recyclebots, that can make filament from waste plastic,” Dr. Pearce told 3DPrint.com this week. “We have developed a new version of the recyclebot with enough control to produce commercial grade filament from more or less anything – we have demonstrated it with pellets, regrind, and even waste composites. The plans are fully open source and most of the parts of the new machine design are themselves 3D printable.”

In a new paper, titled “RepRapable Recyclebot: Open source 3-D printable extruder for converting plastic to 3-D printing filament,” Dr. Pearce and his team relay their continued development of the innovative recyclebot, including the full plans, list of parts, and assembly instructions for the device, which was designed for FFF 3D printer-based filament research.

The abstract reads, “In order to assist researchers explore the full potential of distributed recycling of post-consumer polymer waste, this article describes a recyclebot, which is a waste plastic extruder capable of making commercial quality 3-D printing filament. The device design takes advantage of both the open source hardware methodology and the paradigm developed by the open source self-replicating rapid prototyper (RepRap) 3-D printer community. Specifically, this paper describes the design, fabrication and operation of a RepRapable Recyclebot, which refers to the Recyclebot’s ability to provide the filament needed to largely replicate the parts for the Recyclebot on any type of RepRap 3-D printer. The device costs less than $700 in mate rials and can be fabricated in about 24 h. Filament is produced at 0.4 kg/h using 0.24 kWh/kg with a diameter ±4.6%. Thus, filament can be manufactured from commercial pellets for <22% of commercial filament costs. In addition, it can fabricate recycled waste plastic into filament for 2.5 cents/kg, which is <1000X commercial filament costs. The system can fabricate filament from polymers with extrusion temperatures <250 °C and is thus capable of manufacturing custom filament over a wide range of thermopolymers and composites for material science studies of new materials and recyclability studies, as well as research on novel applications of fused filament based 3-D printing.”

(L-R) Comparison between 3D printed products made from recycled PLA (made), virgin PLA (made), and virgin PLA ( purchased).

According to the paper, the annual worldwide plastic production was 322 million tons in 2015, and that number has been growing 3.86% per year. Incinerating plastic waste, or filling landfills with it, isn’t doing much to help the problem.

“Thus, recycling, is now established in the circular economy as the optimum treatment of post-consumer plastics,” the paper reads. “Unfortunately, there can be significant environmental impacts from the collection and transportation of relatively low-density waste plastics to collection centers and reclamation facilities for separation and reconstruction in traditional recycling.”

Previous research on the recyclebot process using post-consumer plastics shows a decrease of 90% in the embodied energy of the filament when compared to conventional methods of manufacturing, and allows consumers to recycle plastic into 3D printing filament in the comfort of their own home. The paper states that the desktop RepRapable Recyclebot can mostly be made from its own output on any RepRap-based 3D printer, and all of the parts can be easily sourced online or from local hardware stores.

Collected parts ready for assembly.

Co-authors of the paper include Michigan Tech’s Aubrey L. Woern, Joseph R. McCaslin, Adam M. Pringle, and Dr. Pearce.

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