RUG/Pennsylvania/State College/Waste Reclamation System
Contents
Current Progress
Penn State RUG has begun very preliminary initial research on a waste reclamation system for turning polyethylene into filament. Further research will be conducted over coming semesters and information will be updated here.
UPDATE: The spring 2013 semester of the 3D printing class has begun purchasing and assembling the parts for the Lyman Filament Extruder. The project is being worked on in conjunction with other Mechanical Engineering students. Currently the wooden frame is being cut out and is starting to be assembled.
Current: This semester, Fall 2013, two students, Beresford Pratt and Peter Dorsey, have undertook the responsibility of assembling a Lyman Filament Extruder, http://www.thingiverse.com/thing:34653. This extruder allows us to recycle used material and produce new filament to print. We have continued the work from last semester and have made great strides towards completion. We intend to have this extruder up and running before February 2014.
Research
Following Lyman's model we will be able to feed pellets of used Polyethylene into a hopper that leads into a auger. This will then feed the pellets into a heating rod that will then extrude the material out of a brass tip as usable filament. We are currently working with Lyman's Second model and may in the future add on elements from his third model. This could include a cooling pool as well as an attached spool to hold the filament.
Materials
Different types of polyethylene are being considered as material choices. Polyethylene has a low melting point (between 248 and 265 degrees F), can be melted and reshaped repeatedly, non-toxic, and produces little to no fumes. Two different types are High Density (#2) and Low Density (#4).
Processing Considerations
The milk jugs first will need to be shredded. This can be done by hand with scissors but would not be efficient on a larger scale. The idea of obtaining a heavy strength paper shredder is proposed. Other ideas are a blender or home made grinder. To melt the plastic, a heating element is needed. Potential elements for experimentation were considered from a toaster, glue gun, coffee maker, or hair dryer. Nicrome wire is a good idea and can be found in toasters and hair dryers. Leads for further research are to look into "hobby injection molding" and "vacuum forming". We are also able to use the filament from failed prints and over extrusion in this model so that we can make sure to get the most out of our filament.
Observations
A one gallon, HDPE, milk jug was cut into small pieces and placed in an electric oven. The temperature was raised to various temperatures above the melting point range between 248 and 265 degrees F. It was found that when heated beyond 300 degrees F the material begins to "brown". The material, when melted, was not a flowing liquid consistency but rather thick and pliable. This shows that the material will need to some how be forced or pulled to the tip in the forthcoming design.
