3D printing has a plastic problem

It is estimated that over 80% of all product-related environmental impacts are determined during the design phase of a product[1]. Mark Young (Mark Young Design) considers 3D printing, the impacts of design on end-of-life management and the challenges faced when trying to print in an environmentally conscious way.

3D printers are great, aren’t they? So futuristic. But what on Earth are we making with them?

What we’re making, mostly, is plastic. And what happens to that plastic after it’s printed? From my experience, I think most designers & 3D printer manufacturers just don’t care.

With plastic always in the news I feel it’s time to discuss this, after I spent 15 months running the Innovation Lab at Gloucestershire’s flagship Growth Hub. Located within the University of Gloucestershire’s new Business School.

I was part of a fantastic initiative called GRIP – the Gloucestershire Research & Innovation Programme. This was an innovative, fully funded, business support programme, for innovative SMEs in Gloucestershire, which ran from Nov 2017 to March 2020. As part of the wide range of targeted support (IP protection, funding advice, business planning etc.) there was a great perk for clients making physical products – free 3D printing.

This approach allowed us to help a wide range of clients making physical products (over 30 from a total of 130+) bring their ideas to life, without the (often very high) cost of 3D printing. GRIP had installed a professional Stratasys F170 FDM printer and the team had budgeted to do something else unusual – buy every material in every colour. So, we had PLA, ABS & ASA in the full colour spectrum. Plus, the mysterious dissolvable QSR support material:

Abbreviation Long Form Material details
FDM Fused Deposition Modelling The printer melts long filaments of plastic through a nozzle, building up the part in layers. This requires a sacrificial “support structure” (like scaffolding) to be printed too, in either the same or a different material
PLA Polylactic acid A low cost thermoplastic polyester, the most common used in 3D printing
ABS Acrylonitrile butadiene styrene A commonly used production-grade thermoplastic
ASA Acrylonitrile styrene acrylate A UV-stable thermoplastic, similar to ABS
QSR Quick Support Release A waxy support structure material that can be dissolved “away”

I started on GRIP as a client through my business Mark Young Design and later joined the team part time, to run the Lab and help clients with design and manufacturing. There were two initial thoughts when I first signed up and checked the printer specs: “Wow, free printing, in every colour? This is amazing” & “What on Earth is ASA??”

I’ve had parts 3D printed for over 15 years and thought I knew most of the materials, but ASA was new to me. And it was promoted by Stratasys as the best material to use – like ABS but more UV stable, with better mechanical properties. Unfortunately, Stratasys offered no advice on how, or where, this material could be recycled. They do take back and remanufacture some of the printer consumables, but not the materials themselves. We used this service for the many spools of filament we went through.

The University of Gloucestershire has a huge focus on sustainability – they were recently voted the #1 University for Sustainability in the UK. I share this focus, so when I took over the Lab, I was determined to run it as responsibly as I could.

One of my first tasks was to write a leaflet explaining all the technical details of the printer. I added a best practice section with this note on marking the prototypes:

Back to this later. I also repurposed packaging to store samples of each colour. I did this by keeping the “purge towers” (an extra ‘waste’ part printed on each build of ASA & ABS parts to keep the nozzles clean) each time I loaded the printer with a different colour. (If Stratasys offered samples it would have been a tad easier – it took me 6 months to complete the set.)

My first thought was to prioritise use of PLA, as it was theoretically compostable, and apparently made from renewable resources. But with no official compostable certification, I couldn’t recommend it to clients as a circular solution. And it produced low quality parts compared to the ABS and ASA.

The trays that parts are built on are ABS. The students who previously ran the lab had tried to reuse the trays by running them through the Dissolve Tank. This tank contains chemicals that dissolve away the QSR support structure, at high temperature, over many hours. This mix is then diluted and poured down the drain.

They had a great idea, but I noticed it often warped the trays making them hard to use. On my training course I was advised to use fresh trays every time because, as many of us know, keeping the bed as flat as possible on a 3D printer is critical for reliable builds. It also means new ones must be constantly manufactured and purchased. I went through more than 50 of these.

So, after each build, you’re left with a single use ABS tray, with ABS or ASA or PLA parts fused to it, plus a “purge tower” that is a hybrid of ASA/ABS & QSR. What am I meant to do with that?

If we apply Circular Economy thinking, this is bad. In Cradle to Cradle terms we might call this a ‘monstrous hybrid’ – different synthetic materials stuck together in a way that’s almost impossible to separate. Like a pair of trainers, for example.

The University had recently decided to send zero waste to landfill, meaning everything that couldn’t be recycled went to an incinerator 40 miles away in Bristol. These materials wouldn’t be recycled. As the trays built up, this was bugging me, so I started thinking of ways to give these trays another life. I felt a good plan would be to make storage boxes from them – by 3D printing connectors that would interlock to form a box. Sadly I ran out of time to develop this further.

As time went on, I also noticed that nobody seemed to be putting recycle codes on any parts. In fact, over the 15 months, and from the 30+ clients that used the service, the only parts with recycle codes on were mine. That’s probably 30-40kg of plastic, 100+ parts, all out there with no code on to help a human understand what it is. Even if ASA isn’t commonly recycled, it’s important to stop it contaminating the plastics that are.

Now, you’ve all seen the material codes on plastic parts – small symbols like this:

When the parts are made by injection moulding, they can be small and sharp. On 3D printers it’s not so easy.

Legibility depends on the layer thickness, print orientation, font type & size. It can be very hard to make something legible on small parts. Also, the client may decide at last minute to change the material, after the CAD file has been create. So, I kept wondering – why it was up to me to do this? Shouldn’t the manufacturers make this easy to do in their software?

There isn’t a feature in their GrabCAD Print software to add this information. I think there should be.

Material codes added to 3D printed parts, with varying degrees of success

There are further things we can do to understand the environmental impact of 3D printing, such as calculating the electricity (and therefore emissions) required to print a part. As an example, here’s a part I got from a commercial bureau. The figures are based on the best info I could find on power used, and the National Grid’s energy mix. Compared to other manufacturing processes, 3D printing can be very energy intensive: I remember being told that the lasers on some machines are only 1% efficient.

Codes are also useful to keep track of the difference between prototype and production parts, plus to start discussions on recycling the real things.

I did forget to add the code a few times, normally in the rush/excitement of making something new. Something tells me a lot of our environmental problems come from geeks like me, designing stuff because it’s fun to see how clever we are, whilst it’s simultaneously annoying to stop and think about what happens later. I wrote more about this in the 9 Lives methodology I developed a while back.

During my time at GRIP I also went to the launch of a couple of new 3D printers. I brought up the idea of putting these codes on the parts, and how hard it was to do in the software. This brought some blank looks and some interesting comments. Here’s a couple I remember:

“It’s a prototype, why would you throw it away?”

“We work with a F1 team that prints 20 tons of composite parts a month”

From my experience of getting stuff prototyped and manufactured, this kind of attitude is pretty typical. It seems to me the prototype process exists in a bubble, stuck in the Linear Economy thinking of Take-Make-Waste. For me, this is wrong. If we aren’t thinking responsibly at the design phase, is it any wonder we find it hard when production is scaled up?

Every month I get excited marketing emails about new 3D printing materials – ABS with Glass Fibre, Carbon Fibre + Nylon, Filament with Flame Retardants – are there any waste collection streams for these? Are they all designed for landfill or incineration? End of life is simply never mentioned.

Yes, you could argue prototypes often contain very little material compared to mass production. It’s where we want to make mistakes, before those mistakes are reproduced in their millions. So, I’d argue that prototypes ARE made to be thrown “away”. Not that there is any such place as “away”.

Of course, 3D printers aren’t just used to make prototypes. They’re being used for mass production and, increasingly, they’re being used at home to make all kinds of things. I started looking at the online libraries for 3D models you can print – places like Thingiverse. They currently have millions of ingenious CAD models you can download and print. And after an hour of random browsing, I couldn’t find one that had a material code on it.

Again, couldn’t these sites make it easy to add the material code in their software? Perhaps they have a responsibility to do this.

Plastic is all over the news, all over the globe and, increasingly, found inside living things. This stuff is not natural, it needs careful handling. So why is prototyping immune from this? Why are people so enthusiastic about 3D printers, yet giving no thought to what these machines slowly, but steadily, churn out day after day?

There is a huge opportunity for manufacturers of 3D printers to make a Circular system: you make the material to high and consistent standards. You know when it’s printed and could mark it accordingly. And by taking back material, with a confidential shredding service, you could genuinely recycle your clever materials. How many cycles of use could you achieve?

In conclusion, I’ve got a few suggestions for everyone who uses these amazing machines:

  • Designers – add a material code to every part, wherever possible.
  • 3D printer owners – look at what materials you use, think about where they will end up. Ask your material supplier if they recycle what they make. If not, what’s their plan?
  • 3D printer manufacturers – your machines make parts that will not go ‘away’. Help your users to be responsible. Talk to waste and resource professionals before you put exciting new materials on the market. Every material needs an end-of-life plan.

[1] https://ec.europa.eu/jrc/en/research-topic/sustainable-product-policy

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