A new 3D printing method could streamline the manufacturing process for multi-metal parts, reducing manufacturing time and minimizing material waste. The printer uses laser powder bed fusion technology on a platform that rotates the powder deposition and gas flow nozzles while printing to enable a continuous, high-speed printing process.

The printer was built and tested by a team of ETH Zurich undergraduate students, guided by professor Markus Bambach and researcher Michael Tucker.

Although the rotary laser powder bed fusion system is designed primarily for aerospace applications that feature approximately cylindrical geometries, such as rocket nozzles and turbomachinery, it could be used to manufacture annular parts for various applications, including aircraft, gas turbines, and electric motors.

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The new 3D printer allows two different materials to be simultaneously fused by a laser on the rotating platform. Courtesy of Michael Tucker/ETH Zurich.

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Most commercial laser powder bed fusion systems use a rectilinear architecture, where the laser idles for some seconds during powder spreading. When idling is repeated over thousands of layers, it increases production time and costs. The rotary architecture of the new printer enables powder to be applied and fused by the laser simultaneously, reducing the manufacturing time for components by more than two-thirds.

To prevent components from oxidizing while they are being printed, the rotary laser powder bed fusion machine includes a mechanism that blows inert gas over the area where the powder is fused. Soot, spatter, and other by-products are systematically extracted via an outlet. The rotating architecture of the machine allows the local gas flow conditions to be controlled more tightly than they are with a conventional machine.

“At first we underestimated the extent to which the gas flow mechanism affects product quality,” Tucker said. “Now we know it’s crucial.”

The rotary laser powder bed fusion system can process two different types of metal in one operation. Material is only deposited where it is needed within the component, reducing waste. Conventional systems require several steps and a much greater quantity of metal powder to make multi-material parts.

One example of a multi-material component is a rocket nozzle. Typically, these parts are made of multiple metals to withstand the intense heat and pressure of a rocket launch. For example, the interior of the nozzle may be made of heat-conducting copper with integrated cooling channels, and the exterior of a heat-resistant nickel alloy.

The multi-metal printing capabilities of the new printer, in addition to benefiting aerospace and other manufacturing sectors, address a specific challenge faced by the ETH Zurich team — that is, to develop bi-liquid-fueled rocket nozzles for the Swiss Academic Space Initiative to send rockets into space. “For small players like our student rocket team, this sort of multi-material technology has up to now been too complex and too expensive, putting it out of reach,” Tucker said.

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(Left): A conventional 3D printer. (Right): The rotating laser powder bed fusion machine, in which the laser continually fuses the powder. Courtesy of Michael Tucker/ETH Zurich.

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Through trial builds, in-process measurements, and analyses of timing and powder efficiency, the team demonstrated the system’s ability to effectively print annular parts faster than rectilinear systems. The rotary laser powder bed fusion system achieved a 16.6% build time reduction for the rocket nozzle and 10.3% for a gyroid ring compared to a linear system. Savings exceeding 52% are predicted for thin-walled, ring-shaped parts.

“This process is ideally suited to rocket nozzles, rotating engines, and many other components in the aerospace industry,” Tucker said. “They typically have a large diameter but very thin walls.” Although the rotating method is especially effective for producing this type of geometry, the laser powder bed fusion machine can also produce non-axisymmetric parts and arrays of parts.

The students faced several technical challenges, including synchronizing the scanning laser with the rotation of the gas inlet and powder supply. Many of the parts needed for the machine were not commercially available, requiring the team to design, for example, a rotatable connection for the gas inlet and a system to automatically refill the powder during operation.

Nonetheless, the team built the rotary laser powder bed fusion machine in just nine months — and the machine is almost ready for industrial application in aerospace, propulsion technology, and other sectors that need parts that are lightweight and almost cylindrical. Due to its commercial potential, ETH Zurich has filed a patent application covering the rotary, multi-material laser powder bed fusion technology.

So far, the components manufactured using the printer prototype have been up to 20 centimeters (cm) in diameter. The team is investigating how to scale the process to higher speeds and larger diameters, and is seeking industry partners to collaborate with it on the development and implementation of this exciting technology.

The research was published in CIRP Annals — Manufacturing Technology (www.doi.org/10.1016/j.cirp.2025.04.005).

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