First Air-Worthy Metal 3D Printed RF Filter Ready for Take-Off

18th August 2017

Airbus Defence and Space has worked with 3D Systems to achieve a major breakthrough in direct metal printing (DMP) within the aerospace industry. Together the companies have developed the first 3D printed radio frequency (RF) filter tested and validated for use in commercial telecommunications satellites. The project built upon research funded by the European Space Agency (A0/1-6776/11/NL/GLC: Modelling and Design of Optimised Waveguide Components Utilising 3D Manufacturing Techniques).

Telecommunications satellites exemplify the aerospace industry’s relentless emphasis on reducing weight — sending a vehicle into a geo-stationary orbit can cost as much as $20,000 per kilogram. Continuing design innovation and reduced production time are also major priorities, as most satellites are designed for a lifetime of 10–15 years.

These priorities make telecommunications satellites the ideal candidate for direct metal printing. The 3D Systems ProX® DMP 320 used in the Airbus RF filter project enables manufacturers to consolidate parts, improve functionality with shapes and surfaces not possible to manufacture via traditional means, reduce production time and lower costs for customized designs, and decrease weight while maintaining or improving material strength.

 

 

3D Systems’ facility in Leuven, Belgium, has been using the 3D Systems ProX DMP 320 since the machine was in its beta stages. Successful projects include topological optimization, weight reduction and parts consolidation for spaceflight-validated parts such as brackets and strut end fittings for telecommunications satellites. The Airbus Defence and Space project was 3D Systems Leuven’s first foray into RF filters.

 

The Airbus Defence and Space RF filter project demonstrates the ability of 3D printing to enable new design innovation for aerospace parts that haven’t changed appreciably in decades.

RF filters are traditionally designed based on libraries of standardized elements, such as rectangular cavities and waveguide cross-sections with perpendicular bends. Shapes and connections are dictated by typical manufacturing processes such as milling and spark eroding. As a result, cavities for RF filters typically need to be machined from two halves bolted together. This increases weight, adds an assembly step to production time, and requires extra
quality assessment.

Designing the parts for 3D printing enabled Airbus Defence and Space to explore complex geometries at no additional manufacturing cost.

CST MWS, a standard 3D electromagnetic simulation software tool, was used to design the 3D printed RF filters, with little time spent on optimization. The increased manufacturing flexibility enabled by 3D printing led to a design using a depressed super-ellipsoidal cavity. The unique shaping helped to channel RF currents and deliver the required tradeoffs between Q factor—a measure of a waveguide’s efficiency based on energy lost—and rejection of
out-of-band signals.

“The disruptive innovation lies in the fact that pure functionality, not manufacturability, now determines how the hardware will be designed,” says Koen Huybrechts, project engineer for 3D Systems in Leuven. “This project is a classic example of ‘form follows function’.”

“The main benefits of a monolithic design enabled by 3D printing are mass, cost and time,” says Paul Booth, the RF engineer for Airbus Defence and Space in Stevenage, United Kingdom. “The mass is reduced because there is no longer the requirement to have fasteners. With direct metal printing there is also the no-cost bonus to have the outer profile more closely follow the inner profile, so only the really necessary metal needs to be used. The cost/time benefit comes from the reduction in assembly and post-processing.”

 

 

 

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