How AMCM supports ArianeGroup’s space launches

Since its founding in 1989, German AM company EOS has established itself as a strong leader in powder bed fusion technologies. With a large portfolio of polymer and metal AM systems, the company can meet the demands of many industries and applications. However, when specific industry needs exceed its portfolio’s capabilities, EOS has a dedicated subsidiary, AMCM, that makes bespoke systems based on EOS technologies that go above and beyond.

With an expert team made up of industry veterans and specialists in laser optics, material development, and additive manufacturing design, AMCM has brought many boundary-pushing systems to market to meet the requirements of specific applications and customer needs. It is therefore no surprise that the space industry, which has some of the most demanding and challenging specifications, has become an important adopter of AMCM’s systems. We recently got the chance to speak with AMCM leaders, Martin Bullemer, Managing Director, and Felix Bauer, Head of Sales, to discuss the company’s latest (and largest) development project, the M 8K, and how it will be used by leading European space launcher company ArianeGroup.

A multi-year collaboration

AMCM and its parent company EOS have enjoyed a long-running collaboration with ArianeGroup, a joint venture founded by Airbus and Safran in 2015. The company is a—if not the—key player in Europe’s space industry, developing innovative launch vehicle solutions for the European Space Agency (ESA). The latest development by ArianeGroup is the Ariane 6 rocket, a two-stage rocket available in either a dual- or quad-booster configuration.

The Ariane 6 rocket, which is expected to have its debut launch on July 9, 2024, is the result of much hard work and innovation. Notably, ArianeGroup has worked with EOS and AMCM in the manufacture of many rocket components, using a number of metal AM solutions including EOS’ M400 and M290 as well as AMCM’s M 4K machine.

As Bauer explains: “ArianeGroup and EOS had been working together for a few years on different applications. And when there was the need for the successor of the Ariane 5 rocket—the Ariane 6—the company was looking for somebody that could make a bigger machine for those bigger rocket engines. Since we are the ones that make these special machines, a collaboration was started.”

Most recently, AMCM has been developing its largest machine to date, the M 8K adapted to the envisaged component size to meet the requirements of ArianeGroup’s Prometheus rocket engine, a reusable rocket engine that will run on liquid oxygen and methane.

Developing the M 8K

First and foremost, the development by AMCM of the M 8K, a laser powder bed fusion system equipped with eight lasers and with an unprecedented build volume of 800 x 800 x 1200 mm, was made possible through a national grant, which helped to get the project off the ground. As Bullemer explains: “It was very important for us to get initial funding to kickstart the project. Together with ArianeGroup, we discussed where we could get some initial funding and we tried a few routes. Finally, it worked out with an industry fund from the German Ministry of Commerce.”

This cooperative approach and the resulting type of funding means that the M 8K system is not exclusively tied to ArianeGroup. As Bullemer explains, this type of industry fund has benefits, like not having to pay taxes and not having to deal with IP issues. “We’re not tied by contractual details here,” Bauer adds. “We can sell the machine and explore other markets, which is really crucial for us.” When asked about other potential applications for the massive metal 3D printer, Bauer and Bullemer say that the machine could be used for many types of heat exchangers, including server farm cooling, as well as fluid or air management systems.

With the initial national funding, AMCM has been able to do what it does best: develop a bespoke LPBF machine that meets previously impossible-to-achieve requirements. That said, there were challenges in scaling up the size of the system’s build volume.

“When going into these really big systems, there are three major challenges,” Bauer says. “The first is air flow, or how we cover the powder bed with a decent inert gas flow. Second is the optics and ensuring that all that works in a productive and stable way for long-lasting builds and challenging materials. And third is thermal stability, particularly because we are dealing with challenging materials like copper alloys.”

To address these challenges, AMCM has drawn from EOS’ established technologies and enhanced them through innovations like a proprietary airflow design, which is unique to the M 8K. Understandably, Bauer and Bullemer are unable to give too many details on this technology since it is still patent-pending, but they do say that the entire system, including the laser and scanner arrangements, is built around the airflow design.

“Whenever you scale up something smaller, you have to make sure that you keep it reliable and mature,” Bullemer adds. “Because the risks are scaled with a bigger system. We try to take out as many risks as possible through solid engineering—I would call it solid German engineering. We are not interested in cutting costs for the sake: we take the better components just to be sure it will work.”

In terms of the M 8K system’s process control and quality monitoring, AMCM took EOS’ tried and tested solutions like Smart Fusion and EOSTATE Exposure OT and scaled them up. “EOS has done a good job in software and quality monitoring,” Bauer says. “So we have a very strong backbone we can use. We use its technologies, just scaled and beefed up a little bit for the bigger machine.”

Meeting the space industry’s standards

While the M 8K machine is not exclusively intended for space applications, the fact that AMCM is developing it alongside ArianeGroup to print its Prometheus rocket combustion chamber means that the system has to be up to the stringent standards of the space industry. For this machine in particular, which will become the largest LPBF metal 3D printer on the market, there is lots of new ground to cover when it comes to ensuring certain requirements are met.

According to Bauer, AMCM’s partnership with ArianeGroup has been very valuable, as the space company has helped to keep AMCM on the right track. “The partnership with ArianeGroup helps us a lot because they will challenge us by asking ‘can we monitor that?’, ‘can we control that?’, ‘how do you prove this or that?’.” In other words, ArianeGroup has helped AMCM to navigate the needs of space manufacturing.

AMCM for its part could join forces with ArianeGroup to make the most out of metal additive manufacturing. “The initial design for the combustion chamber is from ArianeGroup, and this design is more or less fixed,” Bullemer explains. “In addition to that, however, you can improve the internal cooling performance through additive manufacturing and this is something our experts will weigh in on.”

As many aerospace companies have realized, additive manufacturing has an important role to play in not only making small-series production viable for rocket engines, but also in optimizing performance and efficiency. Design freedom is one important part of this, as additive technologies enable the production of complex internal geometries, like cooling channels that can be built directly into the chamber structure. However, the ability to print materials with excellent heat transfer properties, like copper alloys, is also imperative.

AMCM’s M 8K system can do both. Specifically, the M 8K is being used to print the copper liner inside the Prometheus combustion chamber. “The challenge within the chamber is that you have a massive amount of energy and then you have to cool it,” Bullemer elaborates. “This is usually done with liquid fuel, which runs through the copper liner, while outside you will have a very stable coat of Inconel.”

“What all rocket companies are after at the moment is to have a design where you have better heat distribution in the copper liner,” Bauer continues. This is achieved by integrating complex networks of cooling channels into the copper liner, which circulate cooled gases. This ensures that the heat generated inside the combustion chamber is dissipated properly and that the copper liner stays intact.

Of course, copper itself is a challenging material to 3D print due to its excellent heat conduction and the behavior of lasers. Fortunately, AMCM has extensive experience working with copper alloys. “When we started the M 4K project years ago, we learned how to process copper alloys,” Bauer says. “During that time, it is not just that we learned how to adjust the process for copper, we also learned the common pitfalls associated with printing big copper parts. Now we know where to keep the temperature thresholds of these alloys and we know how important it is to keep the machine running in a particular temperature range.”

Boosting Europe’s space programs

Ultimately, AMCM’s M 8K, M 4K as well as EOS’ standard metal LPBF systems are enabling ArianeGroup to progress in its mission to enable Europe’s access to space. “We are very proud to work with the ArianeGroup and support them to push the boundaries in terms of technology and costs,” Bullemer says of the ongoing collaboration and the imminent production of the reusable Prometheus combustion chamber.

Indeed, the Prometheus program could be game-changing for the European Space Agency, as it aims to offer a reusable engine that costs one-tenth the amount to make existing rocket engines like the Vulcain 2. According to ArianeGroup, the Prometheus engine’s structure will be mostly 3D printed (70% of the total mass). Be sure to watch this space for updates on the Prometheus rocket engine’s development and the launch of the massive M 8K machine. In the meantime, you can read more about AMCM’s custom EOS systems in a recent VoxelMatters’ feature story.

This article was originally published in VoxelMatters’ VM Focus Aerospace eBook. Read or download the full eBook for free at this link.