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Is 3D printing really sustainable?

Is 3D printing really sustainable?

It was an astute and well-timed comment from Stefanie Brickwede in an interview from our recent rail feature that prompted the question which headlines this very article. Brickwede, Head of Additive Manufacturing at Deutsche Bahn, suggested we need to give AM companies a wakeup call “to focus more on ecological sustainability and not just greenwashing.”

Brickwede isn’t the first to use the term “greenwashing”, the idea that a product can be marketed as sustainable without having the credentials to back it up, in reference to the AM sector. The topic has increasingly found its way into conversations amongst those in the industry who want to ensure AM’s green credentials are more than just buzzwords and backed up by real data.

It’s easy to think of AM as sustainable. You’re adding material where needed, theoretically using less than that of a subtractive method. With the advent of distributed manufacturing, you’re hopefully producing much closer to the point of need, reducing emissions along the way, and through digital warehousing, only producing those parts when you need them. With increased freedom of design, you can reduce weight, potentially saving costs and energy over a part’s lifecycle. But it’s not so clear cut.

“It's like a double- edged sword,” Runze Huang, PhD, CEO & Co-founder at ExLattice, Inc. and author of a number of papers focusing on the energy and emissions saving potential of AM, says. “The unique advantages of AM, such as customisation, distributed production, flexibility, and multi-material applications, are creating complexity and unique challenges in the end-of-life of AM products. It needs to be considered more and addressed better now as we still have time before AM entering the mainstream of manufacturing and causing the sustainability issues 20 years later.”

Speaking on a recent episode of the Additive Insight podcast, AM consultant Phil Reeves echoed Huang’s thoughts and expressed the need to consider the full lifecycle of an AM part.

“You have to look at full lifecycle, end- to-end sustainability and I think we do have some issues,” Reeves explains, “certainly on the polymer side, our polymer chemistry which is maybe not as green as they could be; the actual additive manufacturing processes themselves are not as energy efficient as they could be – they haven’t been designed around energy efficiency. If you look at some of them, you pre-heat a significant amount of material to just below its melting temperature, you hit it with a laser – that’s an incredibly inefficient laser – you lose lots of energy in the room, you end up with a cake of material that you then cool down for 24 hours. That’s not an efficient manufacturing process.”

Reeves suggests the next industry trend will need to be around “efficiency” of machines, supply chains and materials but also cautions that if we want to encourage the use of AM for production, not just prototyping, then the industry will need to keep up with environmental legislation.

Reeves continues: “The worry is that we won’t and at some point, somebody will turn around in the corporate social responsibility group of a large car company and say, ‘that material you’re using in prototyping, we can’t use that anymore, we’re going to be legislated against it,’ so I do think we have to think, as an industry, seriously about sustainability.”

Pierre Forêt, Head of AM at industrial gases and engineering company Linde, agrees that we need to be talking more about efficiency. Linde has developed technologies to retain the quality of metal powder prior to printing and ensure optimum atmospheric conditions within the print chamber. Forêt says the biggest potential drawback to AM is energy usage – both in the type and volume of energy it consumes.

“While no one solution can claim to make additive manufacturing more sustainable than traditional production methods, through a combination of technologies – particularly associated to the use of atmospheric gases – the process can be assured to have more reliable, repeatable quality outcomes,” Forêt says. “Once this is achieved, the advantages of additive manufacturing are, at the very least given the potential to contribute to more sustainable production methods.”

Materials are just one part of the value chain where the sustainability question lingers.

“Material reuse within the process is still problematic,” Alex Kingsbury, AM Industry Fellow & Engagement Lead at RMIT University, offers. “There’s no doubt that the printing process, whether it’s metal or polymer, leads to a degradation of the material and limits its reusability. There are also support structures, a necessary evil in many cases, that are waste products. In this respect, metal is much better than polymer, as the metal recycling supply chain is more flexible than the polymers recycling supply chain. For example, a polymer 3D printed product does not bear the universal recyclability symbol. Even if it does, the polymer recycling supply chain is still highly problematic. Metal at the very least, can be channelled through the scrap metal trade. We are also still yet to really properly reach upstream of 3D printed products and properly assess the raw material sources, for example, the metal powder that you use in your 3D printing process. Where does it come from? What is the carbon footprint of that process? Was it made using a fossil fuel energy source like coal or gas? Or was the electricity source hydropower?”

Last year Materialise introduced a solution to tackle material reusability. Bluesint PA12 makes it possible to print with 100% reused powder, versus an estimated 50% currently capable with polymer laser sintering. Following the launch of its Bluesint PA12 printing service back in June, Materialise proposes that if half of all SLS PA 12 parts were printed using Bluesint, this would reduce CO2 emissions from 3D printing by more than 2,800 tons per year.

“The AM industry can and needs to do more,” Andreas Vandyck, Sustainability Coordinator at Materialise, tells TCT. “A first step is for companies to organise themselves in a sustainable way, by considering the impact of their decisions on their workers, customers, suppliers, community, and the environment. But in order to make truly significant contributions, companies need to invest in innovative technologies that help to advance their respective industries."

The company recently conducted a lifecycle analysis with BASF for the production of one million pairs of midsoles. The results showed that for large-series production of identical products, AM had a bigger impact on the depletion of fossil fuels compared to conventional manufacturing. But if you consider smaller series production, the results start to tip in AM’s favour.

More on additive manufacturing & sustainability:

Vandyck adds: “Across the board, “climate change”, clearly stands out as the largest contributing factor for the negative impact of AM technologies. If we look at the carbon footprint, the biggest contributors are the energy consumption of the printing process and emissions related to the production of materials. In comparison, the traditional photo-polymerisation process demands the least amount of energy.”

Is 3D printing really sustainable?

On the metals side, Sebastian Richter, Head of Powder Metals at thyssenkrupp Materials Trading is optimistic and while he agrees greenwashing is an issue, he believes metals are in a better position.

“Manufacturers are now using metal powders to build structures, which means much lower material consumption,” Richter tells TCT. “Additive also allows manufacturers to have design freedom that can lead not only to product and process improvement but also low waste. You can’t achieve this with conventional processes.”

thyssenkrupp Materials UK is the UK distributor for metal powders from raw materials specialist thyssenkrupp, including sustainably sourced stainless steel, aluminium, titanium and nickel-based alloys. As a provider of services to the AM industry too, Richter suggests we must also take a closer look at AM hardware.

“As metal powders are low waste and recyclable materials, potential challenges in terms of sustainability for the additive manufacturing industry may lie with the 3D printing equipment,” Richter says. “Given this is still a fairly new industry, we will probably observe further optimisations of the 3D printers in order to make them more efficient and more sustainable, for example, by improving the filter technology, which is currently complicated to recycle.”

ExOne, for example, is confident that its metal binder jet technology can be considered green, stating that more than 95% of powder can be reused directly in the process via a simple reconditioning step. The company also says that part consolidation and design benefits afforded via binder jet can on average result in 30-50% weight savings, which, in the case of the automotive industry can deliver significant reductions in energy use.

“We have no doubt that our technology is more sustainable than traditional manufacturing methods, such as machining, which generates tons of toxic waste as coolants are applied to cutting tools shaving away sometimes as much as 95% of the stock material to create a part,” Sarah Webster, Chief Marketing Officer at ExOne, says. “While there are new innovations in green coolants, most of those in use today during machining remain petroleum based and nothing in the binder jetting process comes close to the volume or type of waste generated during traditional subtractive machining processes.”

Webster stresses that green benefits can also be found outside of end-use parts, namely in tooling (the company recently launched its X1 Tooling portfolio off the back of its acquisition of Freshmade 3D) where the ability to print tools directly can also reduce waste.

For those metals that aren’t so easy to recycle, 6K Additive has developed a technology which specifically addresses the metal AM market. It’s UniMelt Plasma technology is said to turn virtually any scrap metal into 3D printable material, that includes new materials too. With up to 3 million pounds of titanium capable of being upcycled per year at its dedicated ISO9001 facility, Frank Roberts, President 6K Additive says you can really see the momentum building.

“It really means something to the industry,” Frank Roberts, President 6K Additive, says. “Every facet of who we're dealing with is really starting to ask these key questions and so it's critical that we keep the momentum, that we develop best practices to make sure that we're upcycling all the material that we can, and if it can't be upcycled and go back into the industry, that there's a good home that it's upcycled and going into another industry as an alloy addition, for example. But this is the time where we need to make sure we keep the momentum and keep the messaging strong and really make sure we focus on proper solutions for where these by- products are going.”

Proof that serious attention is being paid can be seen in the hiring of new personnel dedicated to sustainability. EOS’ Head of Sustainability Björn Hannappel, for example, joined in January 2020 and sees the company’s main purpose as “leading the world into responsible manufacturing with industrial 3D printing.”

“Compared to established manufacturing processes like casting or injection moulding, AM is still a rather young and niche technology and cannot currently benefit from the scale effects of local production of raw materials, such as powder, for example,” Hannappel says. “This is certainly a topic, but an area that is improving and will have a positive effect on the decentralised production of AM parts. Additionally, at present there is not a lot of data available to calculate the positive impact additive manufacturing is having. At EOS, we also believe there is a need for more research in areas such as the closed materials cycle, for example, the recyclability of AM parts.”

DyeMansion has also announced its intent to hire a sustainability lead next year. The AM post-processing specialist is one of the first companies on board Europe's mission to become the first climate-neutral continent and on a recent episode of TCT’s Additive Insight podcast, Co-founder and CEO Felix Ewald shared how it is embedding sustainability into every discussion. While Ewald admits sustainability is a complex issue, he remains optimistic about the “huge potential” the AM industry could have, particularly around rethinking global supply chains and decentralised manufacturing.

“I'm afraid that sometimes in our industry, it's easy to say that 3D printing has a great potential impact in terms of sustainability,” Ewald cautions. “But then we should also take it seriously. And I think that's the big task that we have as an industry, not only talking about it but really [taking] action.”

While AM is by no means new, it is still a fairly young industry. Amongst those asked, there is a common belief that the industry can use this to its advantage.

“As an emerging industry, we still have chances to establish the right way at the beginning,” Huang offers. “Of course, we have our own limitations in addressing the sustainability challenges and AM is not a panacea. But I feel the AM industry has potential to be set up as a good example in addressing sustainability challenges as a whole to push traditional manufacturing industries to do more. This will benefit our whole industry for more opportunities and faster growth.”

New people coming into the sector are also keen to encourage the topic of sustainability, as Ewald shares:

“We are still a young company and many people really want to work in start-ups, and in job interviews there is always the question coming up, ‘What we are doing in terms of sustainability?’ It's really a topic that is pushed by our team and our employees and we take it really seriously.”

They’re not the only ones. The Additive Manufacturer Green Trade Association (AMGTA) just announced its first LCA research project with the Rochester Institute of Technology’s Golisano Institute for Sustainability, which will compare the lifecycles and environmental impact of an additively manufactured and traditionally manufactured jet engine low pressure turbine (LPT) bracket. The study will include up to 18 different environmental indicators to quantify the environmental impacts of the part and is expected to be published next spring.

While the task at hand becomes increasingly urgent, with AM uniquely equipped to deliver if we can get it right, Vandyck believes that urgency might actually be just what’s needed.

“The climate crisis is an existential threat. It comes with a sense of urgency that forces us to skip incremental steps forward. Instead, it requires us to drastically rethink the way we develop and create products. And when we dare to think from this bigger perspective, we start to truly innovate and create room for new technologies. Such a climate of radical innovation presents opportunities for AM."

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