Printing Green

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by Kip Hanson

How 3D printing is helping to make manufacturing more sustainable

Recycling of carbide, chips, and cutting fluids. Investing in energy-efficient machine tools. Switching to dry machining or minimum quantity lubrication (MQL). Installing solar panels. Sadly, this short list is about all that any machine shop, plastic injection moulder, or sheet metal fabricator can do to reduce its carbon footprint and make the world a greener place. Metalworking, it seems, is an inherently wasteful process.

But what if there were an alternative way to make parts, one that minimizes material usage, largely eliminates the need for tools and cutting fluids, and produces a complete workpiece in a single operation? Wouldn’t that fit the definition of sustainable manufacturing?


Adding it up
As it turns out, such a technology exists. It’s called additive manufacturing (AM), better known as 3D printing. And while it is far from perfect and faces some of its own challenges in the sustainability department, it’s clear that AM is much greener than its conventional counterparts. 

Consider any mechanical assembly. Because AM is nearly unlimited in its ability to produce complex structures, assemblies that once required dozens or even hundreds of parts to construct can now be printed as a single piece. This eliminates all manner of machining, work-in-process, and assembly time that would otherwise add to the object’s carbon footprint. And because 3D-printed part designs are readily optimized, less material is needed to meet the product’s strength requirements—in the case of components used in the automotive or aerospace industry, this means reduced fuel consumption (also green). 

That’s not to say the grass on the other side of the 3D-printed fence is always greener. For one thing, additively manufactured parts require postprocessing. For polymer parts, this often means a trip to a vapor polisher, a machine known for its corrosive chemicals. For those made of metal, secondary finishing is almost always needed, as in grinding, machining, and vibratory finishing. And for many AM processes, there are either photocurable resins or fine, hazardous powders to contend with during printer operation and which must be disposed of afterward. Each of these offsets some of 3D printing’s sustainability advantages. 


The bigger picture
Yet 3D printer manufacturers will tell you there’s much more to this story. For instance, Andreas Langfeld, EMEA president of Minnesota-based Stratasys Ltd., explains that additive is a digital technology, and is therefore a more sustainable process than those that rely on traditional manufacturing workflows. 

How so? And if that’s the case, why can’t machine shops and sheet metal fabricators also take a digital approach? The answer lies in breaking the global supply chain paradigm. Langfeld cites a report from the consulting firm Global Efficiency Intelligence that states, “an estimated 22 per cent of global CO2 emissions comprise goods and services which have been internationally traded.”

Says Langfeld, “so we have all manner of trucks, ships, and airplanes supplying parts from a central manufacturing hub to different distribution sites across the globe. Because AM has the capability to produce parts both locally and on-demand, there is no excess inventory, nor are there any of the emissions that come with shipping from China and other low-labour cost countries.”

The on-demand argument is an especially strong one. Think about spare parts and MRO (maintenance and repair) items—when these can be 3D printed as needed and in the exact quantities required, the warehouse space to store these parts or the tooling used to produce them is eliminated. That might seem like a small win, but considering the tens of millions of components needed each year for aging aircraft, industrial equipment, and automobiles, the gains are significant. 


Rapid prototyping only? Hardly. 3D printing is quickly becoming a mainstream alternative for low to medium-volume manufacturing.  Image: Trinity WheelerLooking in the mirror
But there are also raw materials to consider. Stratasys is but one AM equipment supplier with an eye on feedstock recyclability. Langfeld notes that its H350 powder bed fusion printer allows operators to re-use leftover PA11 (a type of nylon) powder and add to it as needed with virgin material, a cost-saving activity that has long been limited in powder bed printing. 

“It’s worth noting that PA11 itself is based on renewable castor oil rather than petroleum,” he says. “In addition, many powder bed machine builders allow the mixing of virgin with re-used powder; the benefit comes down to the ratio that is allowed.  Because we can effectively manage the amount of infrared heating, we don’t degrade the leftover powder as much as some, which lets the customer then mix in the re-used material at a higher ratio.”

Similarly, Erik de Zeeuw, project manager and certified manufacturing market manager at Materialise NV in Leuven, Belgium, points to the company’s Bluesint PA12 service as a means to maximize material usage. According to a recent company press release, this “makes it possible to 3D print with up to 100 percent re-used powder, significantly reducing powder waste, and offers customers a more sustainable option for 3D printing.”

With one of the largest printer farms in the world, Materialise can speak from an end-user’s perspective on the challenges of sustainable manufacturing. De Zeeuw agrees with the premise that 3D printing is by its very nature a greener technology for all the reasons given. But he also points out that manufacturers—additive or otherwise—should look in the mirror when evaluating any technology’s carbon footprint. 

“The question is not whether additive is sustainable, but rather what can we do as an industry to make it more sustainable,” he says. “Together with our partner BASF we have conducted lifecycle analyses, and contrary to what many suggest, 3D printing itself is not necessarily greener than other manufacturing processes. It depends in large part on the size of the facility, the size and types of parts being produced, the type of 3D printer and amount of energy it consumes, and so on. That’s why it’s important for everyone to take a hard look at optimising their operations rather than just assuming they’ve checked the box on sustainability.”


Nexa3D has developed a more environmentally friendly washing system, allowing them to recover up to 85 per cent of the cleaning solution. Image: Trinity WheelerSkip the greenwashing
Avi Reichental, CEO, chairman, and co-founder of Nexa3D, a Ventura, Calif.-based additive manufacturing solutions provider, does exactly that. He and Nexa3D’s senior director of strategic communications and ecosystem, Sarah Goehrke, hosted an event recently titled “Sustainability in 3D Printing: The Time is Now.” Both suggested that additive manufacturing, despite its many benefits, has a long way to go before sustainable nirvana is achieved, and that there must be far more discussion on the waste created by crashed builds, support materials, multiple design iterations, and other factors that negatively impact AM’s carbon footprint. 

“All of the processes used in additive manufacturing come with trade-offs,” says Reichental. “Do you really need all these supports? How many of them can be minimized or eliminated? Can waste materials be downcycled or recycled in a responsible way? And how do you make sure that, from the get-go, you effectively optimise the part’s geometry to not just make it lighter and stronger but also use less energy to manufacture?”

As noted earlier, there are also postprocessing activities to consider. Nexa3D has addressed the use of caustic cleaning and smoothing agents by developing a more environmentally friendly washing system, allowing them to recover up to 85 per cent of the cleaning solution. They’ve also adopted “circular design principles” like building their 3D printers and material cartridges from recyclable aluminum and have committed to reducing the company’s energy consumption by 25 per cent over the coming years.

“We’re setting some ambitious goals,” Reichental says. “What’s more, we’re happy to share what we’re doing with anybody who wants to work with us. I think there’s a massive opportunity to educate, communicate, share, and teach thousands of customers how to adopt the framework of how we design and manufacture products, resulting in a positive impact on our planet. That’s what we feel most passionately about.” SMT

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