AMCM is metal 3D printing rocket engines

Specializing in customization and tailor-made 3D printers, AMCM GmbH utilizes its expertise in additive manufacturing to bring cutting-edge technologies to industries that seek to push their own boundaries in innovation – this time with its latest M 8K model 3D printer.

Headquartered out of Bavaria, Germany, AMCM (Additive Manufacturing Customized Machines) was started based on two main objectives: to provide solutions for clients whose needs were not being met by standardized additive manufacturing products and to push 3D printing to its limits.

To accomplish this, AMCM built a team of individuals passionate about the future of 3D printing and who want to leave their mark on the industry.

Founded in 2017 as an agile start-up by EOS GmbH – an early mover in the additive manufacturing field – AMCM offers AM solutions with varying degrees of customization based on proven EOS (Electrical Optical Systems) technology and processes.

Additive copper applications were a starting point for the company's system developments, with the need for faster processes, larger components, and more complex geometries being driven primarily by the aerospace industry.

To achieve these faster processes, AMCM quickly turned to powerful fiber lasers that produce excellent results – thus, the AMCM M 4K was born.

The complexity of 3D printing complete combustion chambers in a single piece requires a printer capable of producing parts that can withstand the force of a rocket. To accommodate sizes as well, the M 4K was the first system in the world capable of printing components up to 1,000 millimeters (3.3 feet) tall.

In a short time, however, AMCM announced the introduction of its M 8K system. While the M 4K currently offers a large build envelope of 450 by 450 by 1,000 millimeters (1.5 by 1.5 by 3.3 feet) and supports four one-kilowatt lasers, the 8K does what its name suggests – nearly doubles everything.

"Designing a system of this size involves a whole range of challenges. The excellent laser, scanner and optics design with our tried-and-tested beam sources is based on decades of process expertise from EOS," said Martin Bullemer, managing director at AMCM. "The build volume is four times that of the M 4K, which also means mass. Therefore, the z-axis of the system must be able to move up to 5 tons of powder with highest precision."

The M 8K will be equipped with eight lasers and feature a record-breaking 800- by 800- by 1,200-millimeter building volume.

"The importance of material supply is often underestimated," added Bullemer. "For printing up to 1.2-meter-tall parts with high productivity and quality, powder management is key. Reliably feeding tons of metal powder over several days is no walk in the park. You do not want to interrupt the process in any case."

Larger rockets, 3D printer

The development of the M 8K was supported by a national grant to improve the competitiveness of the Ariane 6 program.

Ariane 6 is a European expendable launch system under development since the early 2010s led by ArianeGroup on behalf of the European Space Agency. Comparable to United Launch Alliances' Vulcan Centaur, Mitsubishi Heavy Industries' H3, Lockheed Martin's Titan IV, or SpaceX' Falcon 9 and Heavy, the Ariane 6 is another in the lineup of private industry rockets pushing the boundaries of Earth's atmosphere.

The first application of the M 8K will be the printing of the combustion chamber of the ArianeGroup's Prometheus rocket engine. This chamber will be printed from a copper-chromium-zirconium alloy, CuCr1Zr. With a height of approximately the limit of what its M 4K could print and a maximum diameter of 800 millimeters, this combustion chamber will be a future benchmark in terms of dimensions and quality for future interested parties.

Collaborating with ArianeGroup for some time, AMCM's M 4K has been an ideal printer to produce complete rocket engines.

"We needed to find a partner who was willing to work with us to push the boundaries of what's possible. This is literally AMCM's DNA, who have already built an excellent reputation having multiple M 4K systems in this industry," said Jan Alting, head of future propulsion at ArianeGroup. "ArianeGroup projects must meet ESA's strict requirements to be approved for launch. As a result, we place the greatest value on part quality, e.g., material microstructure and surface roughness. We do acknowledge that AMCM was awarded this Federal grant. We are confident that we will be able to solve this challenge in a short period of time and help the company enter new markets. Promoting cutting-edge technological innovation is an integral part of our mission."

With larger parts and longer print runs, often over three days long, process control and validation become increasingly important – as a single flaw in the completed product can scrap the entire component, wasting time and resources.

Despite this, X-ray computed tomography is a growing method for checking the structural integrity of additive manufacturing parts.

With AMCM's SmartFusion and EOSTATE Exposure OT (optical tomography), the company is able to integrate the latest technology from EOS Group into the M 8K system to further improve in-process quality assurance and process monitoring, helping to reduce subsequent testing efforts.

"Metal printing offers the potential to make the rocket engine manufacturing process more flexible, less expensive, and faster," said Mullemer. "Our new M 8K system will be operational within a year. We have promised ArianeGroup the first printed combustion chambers before the end of 2024."