09 Sep. Multi-metal 3D printing for cylindrical components
Almost all modern rocket engines now use 3D printing because it allows structure and function to be combined with particular precision, thereby increasing performance. Students at ETH Zurich have now built what they claim to be the fastest multi-material metal printer: the new laser melting machine rotates powder and gas nozzles simultaneously during printing. This allows it to process multiple metals in a single pass without pausing. According to the students, the machine could fundamentally change the 3D printing of metal parts by significantly reducing production time and costs.
Six bachelor’s students in their fifth and sixth semesters developed the machine as part of the ‘Rapture’ focus project at the Laboratory for New Manufacturing Technologies under the direction of ETH professor Markus Bambach and scientist Michael Tucker. In just nine months, the students turned the idea into concrete plans, built it, and tested it. The machine is particularly suitable for applications in aerospace where cylindrical components are required, such as rocket nozzles or turbines. However, it is also of interest for general mechanical engineering.
Rocket nozzle made of multiple metals
Project manager Tucker explains that the project arose from a very specific challenge: Aris, the Swiss Academic Space Initiative, develops its own rockets and needs special nozzles for liquid fuels. The student team’s goal is to reach the Kármán line in the coming years – the internationally recognized boundary of space at an altitude of 100 kilometers, above which the atmosphere is too thin for aircraft to fly without special propulsion.
In order for rocket nozzles to withstand the extreme heat and high pressure during a prolonged launch, they should ideally be made of multiple metals. For example, the interior of a nozzle can be made of heat-conducting copper with integrated cooling channels, while the exterior is made of a heat-resistant nickel alloy. “For smaller players such as the student rocket team, such multi-metal technology has been too complex and too expensive until now,” says Tucker.
3D printing in rotation
At the heart of the new machine is a rotating platform that enables a fast printing process. Unlike conventional rectangular laser melting systems, which require a new layer of powder to be applied after each fused layer, Rapture’s machine operates continuously thanks to its rotating platform: the machine can simultaneously apply powder and fuse it with the laser. This significantly increases productivity. For cylindrical components, the production time is reduced to less than a third.
Rocket nozzles, rotating engines, and numerous components in the aerospace industry are ideal for this process, says Tucker. They typically have a large diameter but very thin walls. Although the machine can also produce non-axisymmetric parts or entire assemblies of components, the rotating process is particularly efficient for ring-shaped geometries.
On the left is a conventional 3D printing machine, on the right is the rotating machine, in which the laser continuously fuses the powder. Image: Michael Tucker / ETH Zurich
Processing two metals in a single process
The rotating machine can process two different metals simultaneously in a single pass. The new process only applies the material where it is actually needed on the component, thus saving material. To do this, the machine blows a special gas over the area where the powder melts to stabilize the process. Nitrogen prevents the component from oxidizing while it is being printed. Soot, splashes, and other by-products are removed via a targeted extraction system. “We initially underestimated how much this gas flow device influences the quality of the product,” says Tucker. “Today we know that it is crucial.” Thanks to the rotating architecture of the newly developed machine, the gas flows can be controlled much more precisely at the processing point than with conventional systems.
Synchronization of all components
The students had to overcome several technical hurdles in developing the innovative laser melting machine. One of these was to precisely synchronize the laser beam with the rotation of the gas supply and powder feed. Many of the components required for the machine were not commercially available, so the team designed them themselves. These included a rotating connection for the gas supply system and a system that automatically refills the powder during operation. Nevertheless, the student team succeeded in building a machine that looks almost ready for industrial use. For Tucker, this was one of the highlights of the focus project: “It is extraordinary that a team of students developed and built a functional machine in nine months.”
A finished guide ring for a high-pressure turbine with a diameter of 75 millimeters. Image: Michael Tucker / ETH Zurich
Potential for space travel, e-mobility, and more
In addition to its specific use for Aris and the space industry in general, the team also sees potential applications in other areas, such as aircraft or gas turbines and electric motors, where ring-shaped geometries are typical. Due to its novelty and great economic potential, ETH Zurich has filed a patent for the rotating multi-metal laser melting technology. It has also been nominated for the ETH Spark Award.
The components produced with the prototype to date have a diameter of up to 20 centimeters. The research team is now working on scaling the process to higher speeds and larger diameters. To this end, the researchers are currently looking for industry partners who would like to further develop and apply the technology in a cooperation.
Literature:
[M. Bambach, M.R. Tucker: Design and analyses of powder deposition, gas flow, and productivity for a rotary laser powder bed fusion system; CIRP Annals – Manufacturing Technology, 2025, https://doi.org/10.1016/j.cirp.2025.04.005]
Source: ethz.ch
Image: Michael Tucker / ETH Zurich