Varun
Inexpensive desktop 3D printing extrusion has always been an impactful potential ally to 3D Printing users. Filabot and 3Devo have been trying to make this a reality for years, with Filabot focusing on inexpensive units (and now large industrial ones) and 3Devo focusing on high-end lab units. Now a Massachusetts 16-year-old, Benjamin Callahan Davis, has thrown his hat in the ring through making a filament extruder and recycler.
Benjamin is off to a great start in winning the Regeneron International Science and Engineering Fair (ISEF). He won first place in Engineering Technology: Statics & Dynamics, earning $6,000 in the process. He also received the Regeneron Young Scientist Award, which earned him an additional $75,000. A nice haul; I should have thought harder about my volcano science project.
Benjamin has made a desktop recycling system that reportedly is 45% more efficient than other systems. Benjamin’s system uses extrusion and pulltrusion in a low-cost setup to help you produce filament, recycle waste, or repair failed prints. Now we pay $10 to $30 per kilo, which means that you can make 10 iPhone cases for $1 to $3 each. Now that’s super nice, but if we can make filament at home from granulate, that same case would perhaps cost 30 cents. If we can use old PETG water bottles, then the cost of that same case would be solely the hourly energy cost of the printer and recycling system, plus the initial investment in those systems.
This radical change could really make industrial production and at-home printing much more economical and eco-friendly at the same time. We could print things for next to nothing while making plastics last longer. The technology has been possible for decades. Industrial recycling systems like these have also existed for years. You can’t recycle everything all the time, of course. Also, we would probably have to add 30% virgin material along with the recycled material to make it work. Materials also cannot be recycled infinitely, as they lose properties every time they are mechanically recycled. But, given the superabundance of plastic waste and the millions of 3D Printers out there, the potential is staggering.
I reached out to Benjamin to find out more about his project. Benjamin got his first 3D printer in fourth grade, and it warms my heart knowing that kids are growing up with 3D printers nowadays. Through an aunt, he also developed a passion for recycling, and this passion, combined with his skills, led him to create a recycling machine with a bill of materials (BOM) of $1,500. The total cost of the project was $3000. The machine can now produce up to one kilogram of filament per hour, but he believes that he can further improve its performance. In the future, he hopes that in a more commercial version, the components could cost around $1000. That would mean the machine could be available for around $3,000 or so. Benjamin is leaning towards creating a commercial product from his extruder. His target market is schools. Currently, his tolerances are +/- 0.3 mm for extrusion alone and +/- 0.03 mm when using both extrusion and pulltrusion. He has also tested shredded materials in PET, PETG, and PLA.
One of the most intriguing things about this machine is why the pull and push?
“Extrusion (pushing) is what is required in order to melt down the pellets/raw material into filament because it operates at the melting point of the polymer used. Pultrusion (pulling) is used afterwards in order to draw down the diameter of the filament from 2.00 mm to 1.75 mm; in order for pultrusion to work the material must already be a filament. Pultrusion operates below the melting point of the polymer used; it softens the plastic instead of melting it. This is needed because traditionally, when extruding filament out of shredded materials, due to the inconsistent granular size of the input, the resulting filament has poor tolerances. Then, this filament is pelletized (cut back into small pieces) and re-extruded. This is a very energy-intensive process. Combining extrusion and pultrusion allows for the filament to be created at 2.00 mm with poor tolerances, then pulled down to 1.75 mm with proper tolerances (< +/- 0.03 mm). This combination of technologies proved to be 45% more efficient than standard extrusion/re-extrusion.”
By skipping a step, Benjamin’s process could skip a step or require a lot less equipment. The machine itself is similar to others, but with some differences.
¨Firstly, the material to be recycled is prepared through shredding and drying. Then, the prepared material enters the hopper of the machine, where the compression auger feeds the materials through 3 independent heat/compression zones before extruding out of the nozzle at 2.00mm. Next, this rubbery, hot filament is fed through a water cooling system with filament pulling wheels at the end to pull the filament at a constant rate of speed. After, the filament loops around the machine and enters the pultrusion nozzle, where the filament is softened and pulled to 1.75mm. To cool the filament after pultrusion, an air cooling system is utilized, followed by another set of pulling wheels that provide the force necessary to pull the filament through pultrusion. Finally, the filament is spooled, and then it is ready for use.¨
Three heating zones could let you dial in quite a lot of different parameters and accurately dial in melt zone performance for a lot of different materials. Benjamin had to iterate the machine over 50 times and spent over 800 hours on it. The most difficult component was manufacturing the compression auger, and he made that with “hand tools, a drill press, or a band saw.” Apart from assembly, general testing was also a lengthy phase. He tested over 50 different combinations across different filaments and with settings in different heating zones. One thing that he found is that his combined process also produced less particulate matter than separate extrusion and reextrusion processes.
I love this project and hope that Benjamin turns it into a commercial product. So far, extrusion and recycling technologies have been widely available for converting waste, recycled bottles, and old 3D-printed parts into filament. The potential of this development could revolutionize the entire 3D Printing industry, enabling us to create things more efficiently and cost-effectively. But, so far, no one has managed to sell millions of recycling units, even though we’re selling tens of millions of 3D printers. Perhaps with this setup, Benjamin can produce a product that revolutionizes 3D printing, enabling us all to safely recycle at home.
Images courtesy of Benjamin Callahan Davis.
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