3D printing and sustainability: the jury is out…

What do 007's Aston Martin, engine parts for a jet aircraft and a 3D printer have in common? They have all been manufactured using a 3D printer. Dr. Catherine Wilson investigates this developing technology, the myths and its implications for sustainability

Three-dimensional (3D) printers are not new. The technology first emerged about 25 years ago, as expensive, large industrialised 3D printers, used by engineers and designers as a method of rapid prototyping. It is no surprise that first applications came from cash-rich industries, such as medical aids, aerospace and car-making.

It is only in recent years that the technology has been used to make final products. As the process has become less expensive, more accessible and new materials have become available, the technology has quickly gained momentum. Recent years have seen the advance of compact, open-source desk printers (‘or fabbers’) like the RepRap (developed at Bath University), which launched in 2004. Since then, the market for 3D printers has widened with small-scale commercial, educational and home (‘hobbyist’) use rapidly growing.

Over time, news stories have increasingly portrayed new applications, from dental implants to customised toys. The Economist even described the growth of 3D printing as the next industrial revolution, and back in 2009 wrote: “Home-scale, or personalized manufacturing technologies offer a new approach to designing and making objects that will change the way we design, transport, and consume physical products, unleashing new product ideas”.

A global State of the Industry report, published in 2011, by US 3D printing experts, Terry Wohlers Associates, predicted growth of $3.1bn in 3D printing by 2016; the figures show the UK as the fifth largest country for 3D printer usage.

But how do 3D printers work? First, 3D objects are created either by sending a digital product design file (more technically known as Computer Aided Design), or by making a scan of an existing 3D object, to a specialised 3D printer. Then the 3D printer is loaded up with the raw materials (akin to the ‘ink’ in home inkjet printers), which can either be plastics, wood, metals or food, and the user presses print.

The 3D object, of virtually any shape, then prints, as the raw material is squeezed through the print nozzle and deposited as material droplets, or strands, layer-by-layer, over and over again. The process, known as ‘additive manufacturing’, can take anywhere between several hours to several days.

The growth in 3D printing has been accompanied by much debate as to whether the technology is good or bad for the environment Terry Wohlers, President of US-based Wohlers Associates, a 3D printing expert, believes “the increasing popularity of 3D printing will help solve the key sustainability issues of the day”.

Various reports, such as the University of Lancaster’s Big Innovation Centre 2012 report also voice similar messages.

Pro-environment thinking is as follows: conventional methods of industrial manufacturing, such as CNC machining, use a subtractive process. This is essentially where products are made by cutting away at blocks of raw materials.

As Wohler’s points out, “this can result in around 80% of expensive metal becoming scrap”. But with 3D printing, an additive manufacturing process, a minimal amount of material is wasted. “Less waste is much better for the environment”, says Wohlers.

Other general environmental arguments put forward include 3D printers reducing waste because products and parts would only be printed when needed, avoiding waste problems associated with excess or unsold production, including, for example, cost and energy use associated with storage.

Further, customised products are expected to be optimised for their target use, suggesting extended product lifetime. On-site production, local to the consumer, has also been suggested as reducing the need for long-distance transport with associated costs and carbon emissions.

3D printers have also been cited as potentially extending the product life cycle because of their ability to repair and print replacement parts (with recycled materials) and upcycle old products into transformed ones.

Finally, some advocates argue that 3D printers could help reduce global economic imbalances as developing countries could, for example, print their own medical prosthetics, energy generation equipment etc far more economically.

Other 3D printing experts, such as Timothy Gutowski, Professor of Mechanical Engineering, at the Massachusetts Institute of Technology (MIT), is less convinced, however.

“While there are some interesting applications, there is a lack of strong evidence or research that suggests that 3D printing is going to lead to a more widespread sustainable society, in fact in some cases, it may have the opposite effect,” he says.

Gutowski supports this with an example: “It is very easy to combine mixtures and customise 3D products but it becomes much more difficult to break up such a product for recycling purposes”. Likewise, one may create another waste problem if everybody starts printing out 3D objects without thinking it through.

Felix Preston, research fellow at Chatham House, adds further to the debate: “Given the range of possible materials, printing methods and applications, there is no guarantee that [3D printing] will lead to greener production and consumption. The efficiency gains over traditional manufacturing, for example, could easily be offset by growth in consumption or by the life cycle impacts”.

To date, however, few studies have examined the variety of environmental impacts of 3D printing over its lifetime, such as energy use, transportation costs, and pollution, compared with traditional manufacturing. Further large-scale research is needed.

It is expected that sustainability professionals, especially in industry sectors, such as consumer products and electronics, automobiles and medicine, will track 3D printing developments, used by their companies and stakeholders, for sustainability implications.

One issue that may crop up for sustainability professionals relates to the materials used in 3D printing. As Dr Bert Bras, Professor of Mechanical Engineering at the US Georgia Institute of Engineering explains: “Some materials require HSE expertise. Whenever you deal with fine powders, you can get dust explosions and/or respiratory problems. So that’s a real concern for operators”.

When looking for evidence of environmental benefits, Bras advises sustainability professionals to seek proof using ISO14001 standard Life Cycle Analysis (LCA).

However, while 3D printing looks likely to cause disruption. Both in the way we use materials and design products, as limitations and barriers improve, most 3D printing experts are quick to correct the misconception that every home will own a 3D printer.

As with any new technology, there are advantages and disadvantages, and the environmental impacts are hard to anticipate. No one knows exactly what the future holds. Time, perhaps, to print off that crystal ball!

Dr Catherine Wilson is a freelance consultant at Environmental Intelligence Consulting Ltd

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