Understanding the regulatory, testing, and materials challenges of additive manufacturing for space.
There’s no question that additive manufacturing (AM) in space is difficult, but additive manufacturing for space is challenging in its own right. Space-based components face some of the harshest environmental conditions imaginable, with the added complication that servicing them is difficult, if not impossible. These existential constraints impose a particular set of engineering requirements on 3D printed components destined for orbit and beyond. Regulatory, testing and material challenges abound.
Let’s take a closer look at each one.
#1 – Regulatory challenges in additive manufacturing for space
As any aerospace engineer knows, this is an industry built around regulation. For space-based applications of AM, this is arguably the biggest challenge. “A lot of the time, we can get to the desired shape, but convincing the engineering bodies – the regulators – that it’s going to be fit for purpose, safe and reliable for highly critical missions is the real hurdle,” says Michael Shepherd, VP of aerospace and defense at 3D Systems. Part of the issue, as Shepherd explained, is that 3D printing processes have fewer years of historical data while the technology continues to evolve rapidly. That combination means regulators aren’t always satisfied with the available information.
#2 – Difficulties with testing 3D printed parts for space
The obvious solution to regulators’ concerns about additive manufacturing parts for space being relatively untested is to do more testing. Unfortunately, this isn’t as straightforward as it might seem. One of the biggest advantages 3D printed components have over their traditionally manufactured counterparts – geometric complexity – can be a significant challenge when it comes to part analysis and non-destructive testing (NDT).
“In a lot of aerospace applications, you’re really concerned about flaws that may be hidden in the interior of the component,” explains Shepherd. “So, you might be looking at various types of X-ray or computerized tomography, eddy current inspection or fluid penetrant to find very fine surface cracks. With 3D printing, all of that can get harder because the sections can be very complicated shapes which may or may not be amenable to the NDT techniques you’re using.”
Moreover, consolidating multiple components into a single, complex structure – another of 3D printing’s oft-touted benefits – exacerbates this issue further. Beyond the structures themselves, the materials used in additive present a unique set of challenges on their own.
#3 – Materials challenges in additive manufacturing for space
The variety of materials available for additive manufacturing has grown prodigiously over the past decade. This means aerospace engineers have increasingly more options from which to choose when designing 3D printed components destined for space. However, the additive process itself can complicate matters by changing the way even well-understood materials behave.
“We’re printing metals, polymers and composites, but even to the extent that those materials are mature in the aerospace portfolio, a lot of the time the manufacturing process is different,” Shepherd explains. “I got my PhD in Ti-64, and the microstructure you get from using an additive process is different from the old-school, heat-and-beat metallurgy because we’re not forging it; we’re creating it with a very complicated welding process in the form of laser powder bed fusion.”
Hence, even when the chemistry is the same, the mechanical behavior and failure modes of a 3D printed part can differ. This is why extensive testing is so important in AM applications but, as indicated above, that also presents a hurdle for space-based AM parts.
The future of additive manufacturing for space
One thing all three of these challenges have in common is that they can be lessened with time. As more space-based missions are run using 3D printed parts, organizations such as NASA, the FAA and EASA will accumulate more data demonstrating their reliability. Not only will this lower the regulatory hurdles additive parts need to clear, it will also inform future testing as well as materials development. Additive manufacturing has come a long way for space-based applications, and it still has a long way yet to go, but at least it’s moving in the right direction.
