A Sustainability Scorecard for 3D Printing0

Mara Grunbaum | Mon Apr 9 2012

We are, it would seem, at the cusp of a 3D printing revolution. The technology has exploded in recent years, having been used to build everything from car bodies to dental implants to jet-engine parts. And startups like MakerBot, which offers breadbox-sized 3D printers for less than $2,000, are making its capabilities accessible to home consumers, inspiring grand visions of a future where everyone prints out their own children’s toys, replacement dishwasher gaskets, household objects or high-end musical instruments. But would that future really be sustainable?

“This is kind of everybody’s vision of the next best thing since sliced bread and night baseball for manufacturing,” says David Dornfeld, a professor of mechanical engineering who runs the Laboratory for Manufacturing and Sustainability at the University of California, Berkeley. But beyond certain specialized uses, according to Dornfeld and other experts on manufacturing’s environmental impacts, 3D printing doesn’t seem any more planet-friendly than current production techniques — and in some cases it may even be worse.

3D printing, in which material is extruded layer-by-layer onto a platform and glued or fused together to build a finished product, has been used to make prototype parts for more than a decade, but only in the last few years have people started using it to build final products. Since then, the industry has expanded quickly, and consulting firm Wohlers Associates predicts $3.1 billion in growth by 2016.

On the industrial level, the technology, also called additive manufacturing, has three main environmental selling points: Because plastic or metal is laid down only where it’s needed, there’s very little scrap, unlike when objects are stamped or sculpted out of a larger piece of material. The same machine can build many different things, so you don’t have to create specialized machinery for each piece you want to make. And since the printers take direction from digital design files that are easy to transmit electronically, parts and products can — at least in theory — be printed out right where they’re needed, rather than shipped long distances from a factory where they’re mass-produced.

“3D printing by its very nature is sustainable, because it builds from nothing, layer-by-layer, to build an object — you have no waste,” says Cathy Lewis, vice president of global marketing for 3D Systems, which has been developing the technology for industry for many years and recently debuted its first 3D printer aimed at home consumers.

In some applications, additive manufacturing can indeed save a lot of material and energy, says Bert Bras, a mechanical engineer at Georgia Tech who focuses on sustainable design and manufacturing. Since a 3D printer’s nozzle can build more complicated shapes than traditional machining, you can make an airplane propeller, for example, that uses a complex supportive structure rather than many layers of metal to give it strength. The resulting part uses fewer raw materials and weighs less, so it’s less costly to transport.

But for most mass-produced consumer products, the process makes less sense. There isn’t much hard data yet on how 3D-printed products compare to traditionally manufactured ones in terms of energy use, transportation costs, pollution and other potential environmental impacts over their lifetime, Dornfeld says, but some comparisons are clear. Mechanical engineer Tim Gutowski, who heads MIT’s Environmentally Benign Manufacturing group, found in a 2009 study that laser direct metal deposition — a type of additive manufacturing where metal powder is deposited and fused together by a high-energy beam — uses hundreds of times the electricity, per kilogram of metal processed, as more traditional methods like casting or machining.

That’s just one aspect of environmental impact, Gutowski says, but it shows that 3D printing technologies have a long way to go before they match the efficiencies of scale that older manufacturing processes have honed for decades. “I think that needs to be addressed before… we could really scale it up and it would revolutionize how we make stuff on a large scale.”

Additive manufacturing is also significantly slower than most modern mass production methods, and since the raw materials still need to be transported to wherever objects are made, the shipping savings may not be all that significant, Gutowski says. Ultimately, he and others say, 3D printing works out to be a good bet when you want to build complex shapes, customized parts or small runs of products for which creating a mold or machining process would be wasteful and time-consuming, but it won’t likely be a practical replacement for traditional manufacturing anytime soon.

And the dream of Star Trek-style replicators in every home, printing everything from toys to toasters? That may not be the best idea either, according to Bras. As an analog, he says, think of the home photo printer. Sure, you save a bit of gas not driving to the drug store to get your glossy prints. But you also waste a lot of ink and paper when your printer glitches or your photos come out poorly and you start over, which is less likely to happen with a trained professional and a machine built to run off a thousand prints a day. And that’s not to mention the impact of manufacturing all those individual printers and ink cartridges in the first place.

“It’s a lot more efficient if a big machine does it,” Bras says. By the same token, while 3D printing has its uses in industry, “you have to be careful when you hand it out to amateurs.”

Top image: Cardioidal variations. Courtesy Flickr user fdecomite