In what might seem like an intuitively non-obvious conclusion, a recent study finds that 3D printing is both cheaper and greener than traditional factory-based mass manufacturing and distribution. At least, it's true for making consumer plastic products on open-source, low-cost RepRap printers.

A team led by Michigan Technological University's Joshua M. Pearce conducted preliminary lifecycle analyses of three small plastic objects: a child's building block, a spout for a watering can, and a citrus juicer. The three objects chosen were considered typical of those people might want to print at home, and because open-source .STL files are easily available. They were also chosen to test different variables, such as the effect of fill percentage on environmental impact or geometrical complexity. The team included Pearce, associate professor of materials science & engineering, electrical engineering and computer engineering, and Megan Kreiger, graduate student in materials science & engineering.

Hawaii 3D Printing | 3 Small Plastic Objects



The study, published in an open access article in ACS Sustainable Chemistry & Engineering, found that the advantages of 3D printing over traditional manufacturing were mostly due to two major differences. First, the amount of material used for each object is much lower with 3D printing, partly because it's additive manufacturing and partly because fill composition can be easily changed, leading to more efficient shape design and even less material in items that don't need mechanical strength. Second, because 3D printing occurs at the point of use, there's no high costs or environmental impact of shipping products long distances from countries with low labor rates to distant countries that buy the end product.

The study concluded that the total energy demand of manufacturing plastic products can be reduced 41 to 64 percent and emissions can be reduced a similar amount when using PLA with less than 25 percent. Results were even better, at 55 to 74 percent, when using a solar photovoltaic-based distributed electricity generation system, since solar PV systems can be scaled to match existing loads. Reductions were not as great for the products made with ABS, since it requires higher temperatures for the print bed and extruder.

Kreiger and Pearce point out in the article that the aggregate environmental benefits of distributed manufacturing are not yet clear, "due to the potential for increases in the overall embodied energy from reduction in scale (e.g., thermodynamic limitations to working with smaller volumes)." With that in mind, they also mention the fact that different methods are being evaluated to reduce the energy required for the 3D printing build platform.

In an earlier open access article, Pearce and a different team established in a lifecycle economic study that an average household could save up to $2,000 a year making their own plastic products at home with a RepRap compared to buying conventionally made versions. In the new study, the authors note that costs of the manufactured objects can be reduced much further by using filament made from recycling post-consumer materials via open source RecycleBots at the point of use.

Aside from these eye-opening conclusions, I also found this study interesting because it talks about 3D printing as a technique for achieving distributed manufacturing. Distributed manufacturing, often in lower volumes, is being discussed as an alternative to the centralized, high-volume manufacturing that has become the traditional method around the world. As the costs of fuel and the demand for fuel have risen, along with concerns about the environmental impact of emissions, methods for implementing distributed manufacturing are getting a lot more attention. Cloud computing, cloud 3D printing via the Web or via fax, and the emergence of techniques for cloud manufacturing, are all part of this discussion.