Recycling Plastic Into Filament

Plastic is a remarkable material in many ways. Cheap, durable, and versatile, it is responsible for a large percentage of the modern world we live in. As we all know, though, it’s not without its downsides. Its persistence in the environment is quite troubling, so any opportunity we can take to reduce its use is welcome. This 3D printed machine, although made out of plastic, is made out of repurposed water bottles that have been turned into the filament for the 3D printer.

While there’s not too much information available on the site, what we gather is that the machine cuts a specific type of plastic water bottle made out of PET plastic into strips, and then feeds the strips into a heated forming tool. The tool transforms the strips into the filament shape and spools them so they are ready to feed back into a 3D printer. As a proof of concept, it seems as though this machine was made from repurposed plastic, but it could also be made using whatever filament you happen to have on hand.

As far as recycling goes, this is a great effort to keep at least some of it out of landfills and oceans. Unfortunately, plastic can’t be recycled endlessly like metal, as it will eventually break down. But something like this could additionally save on some filament costs for those with access to these types of bottles. Other options for creating your own filament also include old VHS tapes, but you will likely need a separate machine for that.

43 thoughts on “Recycling Plastic Into Filament

  1. I work as a machinist and we produce a lot of plastic waste. A product can easily cause 80% waste from the raw stock, and it all gets thrown in the dumpster. We work with POM, PVC, Teflon, PEEK, Nylon, PVFD…

    It isn’t economical to recycle although PEEK and PVFD are very expensive. The waste is covered in cutting fluid which can be emulsion or weight 8 cutting oil. If we could recycle on site and also have customers accept the product as fully serviceable, it would be a great boon to both the economy and the environment.

    Obviously, I can make any machine which could accomplish this. What I can not do is get through to company leadership that this is something that needs to happen. Being classically educated as engineers, they would ask me for the economic calculation before they would ask for a prototype.

    1. The economic calculation would be obvious if they not only had to pay to buy the material that was wasted, but pay to dispose of it too.

      Laissez-faire capitalism is not really compatible with what needs to be done for the environment.

      1. At least halogen free plastics can easily disposed of in a waste incinerator. Of course it makes sense to use the heat for district heating systems. A lot of oil is burnt for heat anyway, if some of it is turned into plastic in between, it’s not that bad.
        If you want to recycle plastic which is contaminated with cutting fluids, then you must clean that material. That also needs energy and cleaning chemicals. This also has an environmental impact which must be included into the calculation.
        I do not vote against recycling, but you also have to see the whole thing, in which cases it makes sense..

      2. Especially when that attitude is compared to the attitude in China, which makes America look like recycle masters. China generates the most pollution on the planet, and they have fewer incentives than Americans to change that. It will stay that way until the American government starts requiring all imports to be made with the same environmentally conscious requirements. This will have a much larger impact than any American convictions, since our imports now exceed exports to China (Iirc), and any tighter restrictions will merely shift more manufacturing to China…. Making a negative impact.

        1. Living in Beijing, I observed a totally different attitude than you describe: In addition to huge community recycling bins for common things like plastic bottles there are strict rules like glass bottles not even being allowed to legally take out of restaurants (they are stored and returned and washed to be reused), everything that does go in the trash is sorted (laboriously) for metals and other things of value before going in the landfill. They also recently made single use plastic illegal for many applications.

          1. Thanks for describing this Wayne as someone who actually lives in China. I keep hearing people in Western countries blaming China for the world’s pollution, when the Chinese govt currently seems far more wise about recycling and pollution and environmental factors than the govts in some Western countries.

            Living in Australia, I wish the Aus govt gave the environment as much priority as the Chinese govt does!

          2. It’s not the consumer level waste that causes China’s high pollution problems. It’s the industrial level, and I beleive it is more the greenhouse gasses than the solid waste.
            I’m not surprised Beijing has strong laws regarding waste and recycling. Being one of the most populous cities in the world, they would need to keep on top of it intensely. Sort of like the Netherlands having some of the best civil water projects. It’s a necessity.

    2. A fun engineer would ask for a working prototype. A boring engineer would ask for the cost calculations.

      As an engineer myself, I would ask for the working prototype first 😁👍.

      The idea of saving money (less buying prime materials), environment (less waste) and time (prime material already in warehouse) is more appealing to me.

      1. A soon to be fired engineer would ask for a working prototype…doesn’t sound like fun to me.

        Making this machine would be a net loss to the environment AND the company bottom line. Wasting lots of resources to try to build a machine that will only be scrapped. That’s why you run the numbers first. Don’t forget to account for the Engineers time in those calculations. Every hour of my time has to include a share of all the resources I use daily. So maybe you recycle some plastic, but the cost of commuting on my pulse jet scooter exceeds the resources saved. To say nothing of my Tsar bomba repromod project.

        Broadly defined, burning is your best bet for recycling mixed plastic. Burn it hot enough, mixed with gas, and it’s reasonably clean.

        I should start a project. A pulse jet that runs on failed 3d print nests.

    3. the properties that make those plastic good engineering material are the same properties that makes them almost impossible to up/recycle or even burn. even if you could for argument sake make pellets or filament out of them contamination and degradation would make for very poor feedstock with disastrous physical properties.

      1. While I don’t entirely disagree…

        I can’t see how just smashing the scrap together with a hot press (at least for the thermoplastics) despite any oil residual makes for a wasted effort – if you can get lower grade in shop pressed material sufficiently good to actually machine without failure – which isn’t going to prove that hard (for some of the plastics at least) – folks have been doing so with really really primitive home made presses and getting very usable sheet material out. It is bound to be useful now and then for any job where the form or material is more important than the mechanical properties or look.

        For instance I need a chemically resistant stand for something, so it needs to be made of x as y would degrade in this situation, but the stand needs to be massively massively bigger for stability than the mechanical stresses applied to it – so a lower grade, probably weaker, less pretty recycled material stand would be ideal. It isn’t a use case that requires the entire skill set of the virgin source material, just its chemical resistance to whatever environment it will be working in.

        If you have very specific cutting fluids in use for each type of plastic it shouldn’t be too hard to create an automatic washing system bespoke to that cutting fluid and plastic combination.

        Could also perhaps look at changing the cutting fluids used to something easier to wash or evaporate off.

        1. Turns out, the cost of using inconsistent material is higher then the cost of getting good material.

          Measure that cost in dollars or tons of CO2. Same answer.

          There might be a few edge cases where this isn’t true, find those. The won’t be easy to find. Making every stand a custom project will lose more than you can gain. Especially if you have to make 3 stands before you get a useable one.

          1. The very poorly engineered thermoplastic sheet press type things I’ve seen produce really really damn good results.

            And while you might end up with a few extra failures its not going to be 25% success rate, at least if your existing virgin stock success rate isn’t… really really damn poor?, nah some expletive or other fits best.

            So any contract shop that makes lots of varied stuff by their very nature I would think can find many uses for the less perfect stock, heck from what I’ve seen in reality it often seems to be as good as virgin stock, but with that extra thermal cycle that will in most cases make no meaningful difference…

            And in the case of the stand above it wouldn’t be a custom project to use the recycled material – the whole point is in that case the only element of the stock material that really mattered is the chemical resistance, and even if that didn’t matter just to be stable most stands end up using many many times the amount of material actually required to hold the loads perfectly well – not worth the machine time to remove yet more stock, and the weight is often beneficial to COM, its the sort of creation that naturally lends itself to using less certifiable stock – its only really when you need ALL of the material properties to be right on the money as your design is exceptionally marginal that virgin material HAS to be used, for everything else, it really doesn’t matter much, as long as you can get the client to accept the potentially multicoloured and slightly rougher finished parts…

    4. Typically with engineered materials such as PEEK a material certification is provided to verify min material properties (Chemical, electrical, physical, mechanical, etc…). Combing waste from multiple material lots and with unknown quantities of contaminants would start to raise questions on how consistently the material is able to be recycled. Even if you get a block of PEEK, how does it compare to the original source? What is the variation of the result? Do contaminants create regions of poor properties?

      Also, the more you care about those properties, the more likely you are to want to know those values. If you don’t need PEEK strength (or another property), then you should use something cheaper.

    5. At 80% waste, remelting to raw stock wouldn’t be feasible since the plastic becomes harder each remelt. If waste was reduced by other means first, it might be worth trying to remove the cutting oil with ultrasonics, and remelting with an addition of 80% virgin feedstock.

      One thing to note is graphene added to plastics in the coming years will allow thinner stronger plastics for hopefully less waste.

      1. The thing that is being pulled isn’t the extruder; it’s the slitter. There’s plenty of description on the slitting machine, but not much about how it gets compressed/extruded into filament.

          1. A heater and a nozzle make up an extruder, when you add some mechanism for pushing the material into the heater. Which is the part we don’t see anywhere in the documentation.

  2. Great, turning environmentally damging trash into even more environmentally damaging trash. The number of animals, fish and birds killed by monofilament every year is huge.

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