The past three years can be seen as a tipping point for direct metal printing (DMP) in the aerospace industry, as the technology has transitioned from prototyping to producing aerospace equipment parts and assemblies.
During this time, Airbus Defence and Space, in partnership with 3D Systems, achieved a major breakthrough: the first 3D printed radio frequency (RF) filter was tested and validated for use in commercial communications satellites. This project, supported by the European Space Agency, is titled A0/1-6776/11/NL/GLC: Modelling and Designing Optimized Waveguide Assemblies Using 3D Additive Manufacturing.
In RF/microwave systems, it is usually necessary to separate out several useful frequency signals in the signal spectrum and filter out useless other frequency signals. The device that completes this function is called a filter. Therefore, in the wireless communication system, the filter is a key radio frequency component.
3D printing enables Airbus Defence and Space to design new RF filters based on superelliptical shapes
A major industry trend is to increase the capacity of multiple beams within a single satellite. High-capacity satellites such as the Eutelstat KA-SAT made by Airbus Defence and Space can carry nearly 500 RF filters and more than 600 waveguides. Since they are custom designed, most of them can handle specific frequencies. They allow frequencies from the selected channel to pass, while rejecting signals from outside the selected channel.
Communication satellites are a typical example of the aviation industry's need to reduce weight—putting them into geostationary orbit costs $20,000 per kilogram of weight. Continued innovative design and reduced production time are also key, with most satellites having a lifespan of around 10-15 years.
The need to reduce weight, innovate and reduce production time are just the key points that direct metal printing can meet. This RF filter project uses 3D Systems' ProX DMP 320 to help manufacturers integrate filter split parts, enhancing their functionality by improving filter shape and surface, which traditional manufacturing methods cannot provide, and custom designs are also Effectively reduce the production time and cost of the filter. Of course, while improving the strength of the material, it also makes the filter lighter.
The Airbus Defence and Space project is a new challenge for the first RF filter fabrication at the 3D Systems Centre in Leuven. 3D Systems' production center in Leuven, Belgium, has validated the printer during the ProX DMP 320 test phase. Successful projects have included topology optimization, weight reduction, and integrated functional realization of aerospace-proven components, such as brackets and strut assemblies for communications satellites. The ProX DMP 320 is used for high-precision parts and can print on the LaserForm family of alloys (titanium, stainless steel, aluminium, nickel, chromium, cobalt-chromium).
3D printed RF filter designed by Airbus Defence and Aerospace for integration into satellite payload, new filter 50% lighter than previous model, source 3D Systems
Replaceable manufacturing modules increase application versatility and efficient equipment utilization when changing between different molding materials with the ProX DMP 320. Controlled vacuum forming chambers ensure the performance, density and chemical purity of each part.
Integrated structure realization
Airbus Defence and Space's RF filter project fully demonstrates the capabilities of 3D printing, enabling new innovative designs for the aviation industry that has not changed significantly in decades.
Previous RF filters were designed according to traditional standardized elements, such as rectangular cavities and waveguide cross-sections. The shape and connection of components are determined by typical manufacturing processes, such as milling and spark erosion. Then, the cavity of the filter needs to be machined to hold the two parts together. Obviously doing this will be heavier, the parts that need to be assembled will increase production time, and additional quality assessments will be required.
3D printed radio frequency filter internal structure, based on concave superellipse design
Using 3D printing to make parts allows Airbus Defence and Space to have no design constraints and no additional production costs.
CST MWS is a high-frequency three-dimensional electromagnetic field simulation software launched by German CST company, which is used to design 3D printed radio frequency filters, so that design optimization can be realized in a small amount of time. The manufacturing flexibility afforded by 3D printing has resulted in a cavity with a concave superellipse design for the filter. The unique shape facilitates the passage of RF currents and balances the transfer between Q-factor - a measure of waveguide efficiency based on energy loss - and shielding from extraneous signals.
The 3D printed RF filter, designed by Airbus Defence and Space, combines the original split design into a one-piece design, reducing overall weight. 3D printing helps reduce production time and costs.
Paul Booth, an RF filter engineer at Airbus Defence and Space in Stevenage, UK, said: “The main advantages of a monolithic design from 3D printing are volume, cost and time. Because the filter is no longer Fasteners are required to hold the parts together, so the number of parts is actually reduced. With direct metal printing, there is an added benefit that the outer contour of the part is closer to the inner contour. The cost and production time advantages come from assembly and Reduction in post-processing time.â€
Pass rigorous testing
Three aluminum prototypes were printed using different processing paths, which were tested by Airbus Defence and Space at the Stevenage Centre. Simulate the conditions of the test specimen during launch and orbit, including vibration, shock and thermal conditions, such as extreme temperatures and vacuum conditions. All three aluminum samples met or exceeded the test requirements. In addition, the filter after silver plating through the electrolytic process further improves the performance.
In addition to 3D printing, 3D Systems provided related services for the project, including proven powder handling, material density control, proven post-processing and reliable quality control.
Comprehensive benefits are improved
Now that the process for printing the part has been validated and the part meets Airbus Defence and Space's highest aerospace standards, Airbus can start thinking about the ROI of metal printing. The CFO was pleased with the ROI of this project: fast turnaround time, lower production costs and 50% lighter parts!
According to Airbus, "We can reduce the weight by half without wasting a lot of time optimizing components, and with further structural design, the weight can be reduced. The reduction in weight allows the rocket to use less propellant, helping to reduce costs," said Airbus. The requirements for the support structure are also lower, which inadvertently reduces the weight even further.â€
“The success of this project opens the door to more integration of the mechanical and thermal components of RF filters, working towards reducing part count and overall weight. We will also consider integrating more functions, such as test couplers as part of the filter or directly Integrated into the operation of the waveguide. There is more potential to be realized in reducing the weight of the component while reducing production time and cost.â€
A prism is a polyhedron made of transparent materials (such as glass, crystal, etc.). It is widely used in optical instruments. Prisms can be divided into several types according to their properties and uses. For example, the "dispersion prism" that decomposes the composite light into the spectrum in a spectroscopic instrument, the more commonly used is an equilateral prism; in a periscope, binocular telescope and other instruments, the direction of light is changed to adjust its imaging position. "Reflecting prisms" generally use right-angle prisms.
Polyhedrons made of transparent materials are important optical elements. The plane where the light enters and exits is called the side, and the plane perpendicular to the side is called the main section. According to the shape of the main section, it can be divided into three prisms, right-angle prisms, pentagonal prisms and so on. The main cross-section of the prism is triangle, and there are two refracting surfaces. The angle between them is called the apex angle, and the plane facing the apex angle is the bottom surface. According to the law of refraction, light passes through a prism and is deflected to the bottom twice. The angle q between the emitted light and the incident light is called the deflection angle. Its size is determined by the refractive index n and the incident angle i of the prism medium. When i is fixed, different wavelengths of light have different deflection angles. Among visible light, the largest deflection angle is purple light, and the smallest is red light.
In modern life, prisms are widely used in digital equipment, science and technology, medical instruments and other fields.
Commonly used digital equipment: cameras, closed-circuit televisions, projectors, digital cameras, digital camcorders, CCD lenses and various optical equipment;
Science and technology: binoculars, microscopes, level gauges, fingerprint meters, gun sights, solar energy converters and various measuring instruments;
Medical equipment: cystoscope, gastroscope and various laser treatment equipment
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