Everyone wants to recycle their 3D prints, but it is quite difficult to do so. Here’s why.
Novice 3D printer operators might mistakenly assume that the machines simply print objects as required. That’s quite incorrect: they actually print waste, and only occasionally produce a usable, final object.
I’m not sure of the ratio of waste to “good parts”, and it would vary significantly between machines, materials, and profiles. But I am sure that the ratio has increased over the past few years: profiles are better, materials are better, machines are better. Less waste, more actual prints.
But there’s still waste. And with the introduction of filament swapper accessories, the amount of waste may have even increased.
Because of the mountains of plastic waste, many 3D printer operators hope for a way to recycle that material. Ideally, it could be turned into fresh filament for subsequent print jobs.
Unfortunately, this is likely a fantasy and will never occur for a variety of reasons, including:
- Industrial equipment to perform proper filament production is expensive and large.
- Even desktop filament production systems far outweigh the cost of simply buying new spools.
- It is usually impossible or infeasible to accurately sort waste by material type and colour.
- Recycled plastics are much weaker than fresh material due to molecular degradation.
- Recycled plastics will often not work with original material print profiles due to degradation.
That said, some ventures still attempt to produce recycled filament. You can purchase recycled PETG from several sources, including Prusa Research. However, these all suffer from mild degradation and are typically not less expensive than fresh filament that is guaranteed to work properly.
I read a story about an operation in British Columbia that is attempting to recycle plastic from local scraps, and the story illustrates many of the challenges.
The “Rogerie” is a “recycling studio” in Kelowna, where the owners (the Rogers family) collect plastic and produce both filament and useful items for sale. In the story, several of the barriers show up:
“The Rogers try to source plastic locally as much as possible, but the bulk of their materials comes from a supplier in Ontario. It’s labour-intensive to source plastic, and the stuff from Ontario comes prewashed and ready to use as pellets.”
This confirms the challenges of obtaining quantities of uniform material. Here, the Rogerie has to go outside of the manual collection paradigm and obtain it from an industrial source.
”From the Rogers’ perspective, not all plastic is good plastic. To start, it needs to be commercial grade, meaning it’s designed for consumer items like food packaging. They discovered that fridge shelves and drawers work well for their reuse process.”
This illustrates the molecular degradation problem. A material isn’t good if it is not as strong as it should be, so they’re focusing on materials that don’t degrade as much, or materials like ABS that were so strong that degradation leaves them in still reasonable condition.
”Through a variety of experimenting, the Rogers also have found that PLA, or polylactic acid, which is commonly used to 3D print with and is derived from fermented plant starch like corn, isn’t a great material for them to use.”
They found that the degradation of PLA was so severe that they don’t even bother with it anymore. In addition, PLA is just not a great material for practical parts that must be exposed to heat, UV light, or mechanical stress. Recycling just makes that even worse.
Despite these constraints, the Rogerie has managed to recycle six tonnes of material over time, which is notable — but will hardly put a dent into the millions of tonnes of plastic produced annually.
Does this mean we shouldn’t recycle plastics? By no means — we should do what we can. The problem is that “what we can” is a lot less than we imagine.
Perhaps the best approach for 3D printing is to make the devices more reliable to avoid print failures, and use low-waste-style colour-changing technologies. Those would each dramatically lower the use of 3D print materials on FFF systems.
Via The Tyee
