Sustainable 3D manufacturing - a new way of doing business and creating value.
3D printing as a sustainable manufacturing technology
3D printing is often viewed as one of the key sustainable technologies, for a variety of reasons ranging from lower waste, local production, and design optimization. Companies leveraging 3D printing are able to reduce their carbon footprint, use less energy, and create less waste and consume fewer raw materials.
Design more efficiently
3D printing allows engineers to make parts that are unachievable with other manufacturing methods, allowing greater freedom of design. With new computer-aided design techniques such as topology or generative design, a part can be re-designed to be more lightweight, saving material costs. Multiple parts can be integrated into one design, which saves material costs plus the time and labor associated with assembly.
In one case study completed at Northwestern University, researchers estimated that by replacing a number of routine components with topology optimized 3D-printed parts, overall aircraft weight could be reduced by 4 to 7 percent, with fuel consumption lowered by as much as 6.4 percent.
another example is a redesign completed by GM on one of it's automotive components. GM consolidated eight different components of a seat belt bracket into one 3D printed part. This 3D printed seat bracket is 40% lighter and 20% stronger than the original part. GE estimates that the improvements made possible by 3D printing help to reduce overall weight by 5 percent and improve brake-specific fuel consumption by 1 percent.
Compared to traditional manufacturing technologies, 3D printing can reduce wasted materials, depending on which technology 3D printing is compared to.
When compared to CNC machining, 3D printing has a significant advantage because of it's manufactuirng process. With a subtractive process like machining the material is cut away from a solid block to create a final part. In many cases, only a small percentage of the material goes into a final part, with the cut-away material often exceeding 50 percent. 3D printing builds parts layer-by-layer, which results in very little excess waste (depending on the process).
3D printing is also often compared to injection moulding. The molds used for injection molding can only be used for one specific design, meaning that each design change requires a new mold. For low-production manufacturing or prototyping this can lead to a great deal of material waste. Also, because injection molding is an expensive process to set up, manufacturers often mold more parts than necessary, keeping extra parts in inventory and eventually throwing away unused or obsolete parts. In contrast, 3D printing allows manufacturers to produce the exact amount of parts needed with a very short turnaround time (usually less than a week), which saves raw materials and storage space.
Any industrial process requires energy to run, including 3D printing. From a sustainability standpoint, energy consumption rates directly correlate with environmental considerations, like CO2 emissions.
3D printing, particularly with metals, is by no means a low-energy technology. However, some studies show that it can be more energy-efficient than most conventional manufacturing processes.
A study, conducted by metal 3D printer manufacturer, Digital Alloys, compared the energy consumption of different metal 3D printing technologies with CNC machining.
At the manufacturing stage, energy consumption is indeed larger with metal 3D printing processes, particularly laser PBF.
However, when considering different factors, like material waste, the possibility of material recycling and post-processing, it’s been shown that machining is the most energy-consuming process, due to the amount of material waste – (in Digital Alloys’ example it was more than 90 per cent).
Manufacturing energy consumption of 1 kg of titanium aerospace part [Image credit: Digital Alloys]
That said, not all agree that metal 3D printing is more energy-efficient than traditional technologies.
Timothy Gutowski, head of MIT’s Environmentally Benign Manufacturing (EBM) research group, states that ‘additive processes tend to be more energy-intensive … because they’re slower. They use a lot of energy to produce the same amount of product.
In fact, most 3D printing processes are something like seven orders of magnitude more energy-intensive than high-volume conventional manufacturing processes’, he explains in an interview with The Fabricator.
The truth, as always, lies somewhere in between. While 3D printing can be energy-intensive, choosing the application suitable for the technology and optimising its design will help to offset high energy consumption. It will also result in an overall energy-efficient system, where this part will be used.
On the way towards sustainability
With so many AM technologies out there, there’s no simple answer to the question of 3D printing’s sustainability. Some processes have the drawback of non-recyclable materials, while others are plagued by high energy consumption. What’s encouraging, however, is the fact that 3D printing tends to be more resource-saving, particularly compared to subtractive technologies. And it also opens the door for more efficient designs that contribute to lowering manufacturing and inventory requirements and, ultimately, help to reduce fuel consumption. Our verdict is that 3D printing is not entirely ‘green’ technology, but with the right approach, it can come closer to becoming an incredibly powerful sustainable manufacturing solution.