New space, new applications: Sintavia CEO on 3D printing and rocket building

If the MakerBot Replicator was the poster child for the 3D printing maker movement, those huge, customised metal laser sintering systems from EOS’ AMCM GmbH business may be well on their way to being that of the additive manufacturing (AM) space race.

First adopted by new space launch outfit Launcher to 3D print a liquid rocket engine in a single piece back in 2019, further modified EOS systems from AMCM, short for Additive Manufacturing Customized Machines, have been acquired by UK-based Orbex to ramp up its in-house capability for the production of more than 35 large-scale rocket engines and main stage turbopump systems per year, and most recently Sintavia, which took delivery of two M4K-4 systems this summer.

For the Florida-based metal AM provider which focuses primarily on the aerospace and defence industries, it’s a journey that began towards the end of last year as demand from customers for a more optimised way to print large-scale, single- component metal parts for aerospace soared. Now, with two M4K-4 systems joining its ever-expanding line-up of AM equipment, Sintavia believes this new capability will provide a North American first for commercial aerospace and space customers.

“As we have developed the company and as we’ve grown, there’s been a coalescing around certain part categories which are really good for additive,” Brian Neff, Sintavia’s Chief Executive Officer, told TCT. “One of those categories is in regenerative rocket thrust chamber assemblies (TCA). This is an area where virtually 100% of all thrust chamber assemblies currently in the market are being printed including in more traditional models. I think that this has been known as a very good part for additive because the way regenerative cooling works is very similar to a heat exchanger with an internal passageway flowing very, very cold liquid propellant up into a very hot chamber. It’s a great part for additive.”

Sintavia’s current AM capacity would be the envy of most engineers. With 30 high-speed printers in-house, including multiple from GE Additive, TRUMPF and, of course, EOS, including eight M400-4 quad laser printers, Neff shared how the company was already well equipped with the experience and strategies needed to enter the rocket building arena. What they needed was to go bigger.

“The limitations that exist on current machines are that they’re just not tall enough,” Neff explained. “The way that people have done it in additive up until now has been basically printing three parts and building flanges and welding them together. What the M4K allows us to do is actually manufacture each thrust chamber assembly as a monolithic piece. So you can manufacture the injector, the barrel, the nozzle as a single unit, which completely changes the game. Every time you’re joining two components together, you have to create a larger flange, which becomes a heat sink, which affects the performance of the rocket. You’re not able to reach certain cooling strategies inside the thrust chamber assembly because you have to join them in post-processing, and everything has to align perfectly. It’s a sub-optimal way of printing these TCAs. With the M4K, I think it’s a game changer, particularly for the rocket propulsion industry, in the sense that you can go back and redesign your components to do away with any sort of flanges. That’s a really, really big deal.”

Additive advantage

According to AMCM, Launcher’s E-2 engine combustion chamber was developed as an “AM-capable combustion chamber from the very beginning” to bring together benefits such as those described by Neff into a single structure. The same can be said of Sintavia’s customers who the company is now working closely with to redesign parts to reduce assemblies and take advantage of the M4K-4’s 450mm x 450mm x 1000mm build capacity for TCAs and other thermodynamic parts and aerofoils.

“Right now, we have one customer that prints a large heat exchanger in four pieces,” Neff said. “Now we can do that as a single unit so long as you can figure out how to get the powder out of heat exchanger – that’s the key. We have developed ways to do that.”

The M4K-4 has been described as a “stretched and widened” version of the EOS M400-4 due to the larger build capacity, more powerful lasers and upgraded cooling system. Once installed, Sintavia plans to put the machines to work with high performance copper and nickel alloys. The similar architecture to the M400-4 means Sintavia already has three years of hands-on experience with the platform to draw from. Neff offers an aerospace analogy whereby if a pilot is qualified to fly a 767 aircraft, they can also pilot a 757 or similar. Of course, there are considerations to be made due to the build scale. For example, AMCM shared with TCT how deformation of the workpiece due to the high thermal load during build-up can be counteracted with accurate simulation tools, but Neff is confident that Sintavia is armed to make it work for what has been described as “overwhelming” demand from customers. Notably, despite the disparity in market size, much of that push to innovate is coming from the space segment rather than aerospace.

“What we’ve seen is that the commercial space industry is pulling the commercial aerospace industry into greater adoption of additive, which is great to see,” Neff elaborated. “The commercial space industry, if you take just the launch aspect of it, is very small still compared to commercial aerospace. Even with the parts that we’ve manufactured for that world, usually on the business aviation side at this point, we’ve seen a very sort of slow adoption historically. […] They’re seeing the way that these rocket designers and rocket manufacturers are looking at additive and I think that’s created somewhat of a pull to the market and that’s really wonderful to see because I love the rocket industry and I think it’s got an amazing future but I think that commercial aerospace is really just such a big market that, for us to be a big player, is really one of the goals that we have.”

The decision to bring these new machines in-house was driven by the requests of commercial space launch customers to create TCAs with fewer traditional joining steps, optimise regenerative cooling passages and, as a result, reduce lead times and complexity. That combination of advantages, according to Neff, is crucial.

“In additive, you have to be fixing a problem,” Neff explained. “You have to be doing something better or faster or cheaper, hopefully all three, in order to be successful. I think people in the industry are still, in a lot of ways, like ‘well, I can print this a different way and that’s what makes it better’. No, what makes something better is, is it faster or cheaper or does it perform a lot better? In this case, our customers came to us and said, ‘we really want to do away with these flanges, it takes time, we’ve got to machine them, there’s a weak spot and it is sub-optimal from a flow standpoint.’”

Taking a moment to ponder future possibilities, while Neff is keen to emphasise that using additive is about uniting the right application and benefits, for those companies like Launcher or Relativity Space who have ambitions of fully 3D printing entire rockets and engines, he believes there’s value to be found in looking beyond simply what we can achieve today.

“If you want to get kind of far out, you’re not going to have a foundry on Mars,” Neff posits. “You’re going have to print everything when you’re on Mars. I think when people say that they’re really trying to think a step ahead. They’re thinking, well, when we’re on other celestial bodies, even the moon, people will try to print with solar energy and moon dust and this is going to be the manufacturing technology that’s used. You’re not going to have this big melting cauldron of hot metal that you’re pouring into shapes and then wasting all this stuff. You’re going to be using 3D printing. I think when companies market in that direction they’re also saying to the market, ‘we can do it here and then we can do it up there in space.’ I think that’s a really cool thing.”

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