When it comes to 3D printing in the aerospace sector, France-based Airbus is one of the biggest adopters of the technology, and the company has teamed up with big names in the additive manufacturing industry like Dassault Systèmes, Sciaky, and Renishaw to develop and incorporate 3D printed airplane components. Recently, the company’s Defence and Space division, which formed in early 2014 and is based in the UK, worked with 3D Systems to use its Direct Metal Printing (DMP) technology to manufacture what it says is the very first metal 3D printed radio-frequency (RF) filter to be tested and validated to use in commercial telecommunications satellites.
This is a pretty big breakthrough, as DMP technology has allowed Airbus to save on manufacturing cost, time, and mass of the RF filter; the work, which could change how aerospace companies around the world design and manufacture RF filters and even waveguides, was built upon European Space Agency-funded work. Airbus used the 3D Systems ProX DMP 320 3D printer for the RF filter project.
“Airbus Defense & Space is working more and more with 3D Systems’ Customer Innovation Center in Leuven specifically in the area of Direct Metal Printing applications, including more RF filters,” Koen Huybrechts, project engineer for 3D Systems in Leuven, told 3DPrint.com.
“We find that once we succeed in helping customers set up their first successful case and positive business model, there’s opportunity for longer term developments. Moving away from part optimization and thinking in function of system performance shows a clear focus to maximize the benefit from additive manufacturing. Making use of our latest 3D Systems’ ProX DMP 320, it’s truly a promising trajectory for our On Demand Manufacturing services.”
A high-capacity satellite, like the Eutelstat KA-SAT, can carry almost 500 RF filters, and over 600 waveguides, the majority of which can handle specific frequencies due to custom designs. They allow frequencies from chosen channels to pass through, while rejecting signals from outside the selected channels. It can cost nearly $20,000 per kilogram to send a vehicle into a geo-stationary orbit, so weight reduction in the field of telecommunications satellites is extremely important; additionally, most satellites only have a lifetime of 10 to 15 years, so lowering production time and making better designs are also priorities.
“The main benefits of a monolithic design enabled by 3D printing are mass, cost and time. The mass is reduced because there is no longer the requirement to have fasteners,” explained Paul Booth, the RF engineer for Airbus Defence and Space. “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.”
Typically, RF filters are designed with standardized elements, like waveguide cross-sections with perpendicular bends, and rectangular cavities; these cavities are traditionally machined from two halves which are bolted together, which means extra production time and component weight. 3D electromagnetic simulation software tool CST MWS was used to design the RF filters, which used a depressed super ellipsoidal cavity.
Huybrechts said, “The disruptive innovation lies in the fact that pure functionality, not manufacturability, now determines how the hardware will be designed. This project is a classic example of ‘form follows function’.”
Thanks to intense testing by Airbus Defence and Space, it was determined that the different surface topology in 3D printed metal parts would not be an issue for the RF filter.
“The microscopic topology is different in the 3D printed part than in a machined part. Machined surfaces have sharp peaks and troughs, while the 3D printed surface is spheroids melted together so there is less sharpness,” explained Booth.
“We were very pleased with the work that 3D Systems did for us and many inside Airbus have commented on how good the surface finish is. We did some x-ray CT scans and have been impressed with the density of the part and the general surface quality.”
Three aluminum samples, which were 3D printed on the ProX DMP 320 with different processing paths, were tested by Airbus, with conditions that mimicked what the parts would have to deal with in real launch and orbit situations, like shock, vibration, and temperature extremes. Each of the samples met or exceeded the stringent requirements, and the project delivered a strong ROI for the RF filter through reduced production costs, faster turnaround, and a weight reduction of 50%, which makes the overall system far more efficient.
“The success of this project opens up the possibility of much greater integration of RF filters with mechanical and thermal components to reduce part count and overall mass. We will also look at integrating more functionality such as test-couplers as part of the filter or directly integrated into waveguide runs. There is a huge potential for reducing mass while cutting production time and costs,” Booth said.
In addition, 3D Systems helped Airbus with certified powder handling and post-processing, as well as process and quality control. Discuss in the RF Filter forum at 3DPB.com.[Source/Images: 3D Systems]