January 26, 2020
Note: Ray Huff, associate engineer at Wohlers Associates, authored the following.
No one is surprised to hear that people produce copious amounts of waste every day. A 2017 study found that over 300 million tons of waste plastic is generated annually. The question of how to reuse this material, rather than leaving it to degrade over millions of years, may be tiresome. Fortunately, AM is bringing new options much closer to home in a variety of ways.
Companies are looking at methods of using some of this waste material for AM. GreenGate3D produces and sells plastic filament from 100% recycled polyethylene terephthalate glycol (PETG). I recently bought a spool and I am making useful home goods with it. Filamentive, NefilaTek, Refil, RePLAy 3D, and others have produced fully or partially recycled filaments. Research shows that recycled filament is slightly weaker than virgin plastic, but this is predictable, which means that it can be accounted for in design. As proof of this, the U.S. military has used recycled plastics to build bridges that supported Abrams tanks in at least two cases.
In a recent article, 30,000 water bottles were recycled to 3D print a public structure in Dubai. The pavilion, called Deciduous, showcases how AM can be applied to creative structures using materials that would otherwise be waste. An advantage to using AM is the option of repurposing locally produced materials. With cleaning, grinding, and extruding technologies, such as those advocated by Netherland-based Precious Plastic, nearly anyone can recycle plastics in their hometown.
Recycling initiatives are not restricted to polymers. Newly renamed 6K (formerly Amastan Technologies) of North Andover, Massachusetts has developed a method of grinding and melting recycled metals into spherical powder particles for AM. The company is expected to commercially launch its materials soon. Similar techniques can be applied to produce wires and sheet materials for metal AM. The AM supply chain has not developed sufficiently for recycled materials to economically replace virgin materials. Growing interest, investment, and global conscience is sure to tip the scale, hopefully within a few years.
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