As a society we throw away countless tons upon tons of plastics, which largely end up in landfills. Recycling, when done, means transporting these otherwise usable materials to an industrial plant, but what if you could instead reform these plastics into something useable at home – at least locally on a smaller scale? That’s the idea behind this automated injection molding machine by the SOTOP-Recycling team (Manuel Maeder, Benjamin Krause and Nadina Maeder).
The "Smart Injector" receives plastic (waste) chips in a hopper, then sends them through a heating pipe with an extrusion screw. A powerful NEMA 34 stepper motor drives this screw using a 6:1 gearbox. Six sleeves provide heat to the plastic. Three separate PID controllers are implemented with temperature sensors arranged along the pipe, allowing for independent control of the different zones.
Plastic is formed using a die setup, with two NEMA 17 motors employed to crank down screws and push the forming tool into place. An ejection mechanism then pops the new part off, in the case of the video below. a smartphone cover made in just minutes. The Smart Injector runs on an Arduino Mega, though the machine does need a bit of human interaction in the process at this point.
A lot more information is available in SOTOP-Recycling's post, so with just a “bit” of work, you too can turn your waste into something usable!