Smart Twist in 3D Printing Swiss Students Develop the Fastest Multi-Metal 3D Printer

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ETH Eidgenössische Technische Hochschule Zürich

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At the Swiss Federal Institute of Technology Zurich (ETH Zurich), it is now possible to additively process multiple types of metals simultaneously—patent pending ...

Almost all modern rocket engines are now manufactured using 3D printing because it allows for precise integration of structure and function to enhance performance, say researchers from ETH Zurich. To withstand the extreme heat and high pressure during prolonged launches, rocket nozzles ideally need to be made of multiple metals. For example, the interior of a nozzle can consist of thermally conductive copper with integrated cooling channels, while the exterior is made of heat-resistant nickel alloy. Students of the university have now also built the fastest multi-material metal printer for this purpose, as emphasized. During the process, the laser-based 3D printer simultaneously rotates powder and gas nozzles. This enables it to process several metals in one pass without interruptions, they say. The machine has the potential to fundamentally change the 3D printing of metal parts by significantly reducing production time and costs. The system was developed as part of the Rapture focus project at the laboratory for new manufacturing technologies. Within just nine months, students from the fifth and sixth semester turned the idea into concrete plans, built the printer, and tested it, as emphasized. The machine is particularly suited 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. The components manufactured with the prototype so far have a diameter of up to 7.9 inches.

Print Components Made of Two Metals in One Go

The centerpiece of the new machine for additive manufacturing of metal components is a rotating platform that ensures the fast printing process, they say. Unlike conventional rectangular laser melting systems, where a new powder layer must be applied after each fused layer, the Rapture machine operates continuously due to the rotating platform. It can simultaneously apply powder and fuse it with the laser, which inevitably increases productivity. For cylindrical components, manufacturing time is reduced by over 66 percent, as noted by the Zurich researchers. Rocket-typical cylindrical components usually have a large diameter but very thin walls, which suits the additive manufacturing process, they add. Although the machine can also produce non-axisymmetric parts or entire assemblies of components, the rotating process is particularly productive for ring-shaped geometries. The rotating machine can process two different metals simultaneously in a single pass. Conventional systems require multiple steps and significantly more metal powder for this. Moreover, since mixed powder is difficult to separate and reuse, it is often discarded as waste today. The machine also blows a special gas over the area where the powder is fused to stabilize the process. Nitrogen prevents the part from oxidizing as it is printed. Soot, splashes, and other byproducts are safely removed via an exhaust system.

Additive manufacturing

Basic knowledge 3D printing

These Challenges Had to Be Overcome By the Swiss

During the development of the novel laser melting machine, the students also had to overcome several technical hurdles. One challenge was to synchronize the laser beam precisely with the rotation of the gas supply and powder feeding, as stated. Many of the components needed for the machine were not available commercially, so the team simply designed them themselves. These include, for example, a rotary connection for the gas supply system and a mechanism that enables automatic refilling of the powder during operation. Despite all the difficulties, the team managed to build a machine that almost appears ready for industrial use, as emphasized. The team now sees potential applications not only in the specific use for rockets (such as the Aris system) and the aerospace industry in general but also in other areas—such as aircraft or gas turbine manufacturing and components for electric motors, where ring-shaped geometries are also characteristic. Due to its novelty and high economic improvement potential, ETH has also filed a patent for the rotating multi-metal laser melting technology. Meanwhile, the innovation has also been nominated for the ETH Spark Award.

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