Exploratory Concepts

Ready-for-Flight Antenna in Powder Bed Fusion

Thales Alenia Space is a french aerospace manufacturer that has played a significant role in space exploration for more than 40 years. As new technologies usher in the new era of space exploration, reducing overall lead time and increasing throughput becomes especially important in staying competitive in the growing market. Learn how Thales used the FormUp 350 and aluminum AS7 to achieve their additive manufacturing goals in this case study.

INDUSTRY

Space

CHALLENGE

Design and build a monolithic antenna using additive manufacturing that meets ECSS qualifications and supports the customer’s goal of achieving TRL 3 maturity for additively manufactured antennas.

KEY BENEFITS

• Global distortions of the antenna: ±0.3mm
• Reduced weight: less 600 gr
• Production rate: 1 antenna /day /machine
• Reduced post-processing

Reduced lead time

Creative Shape

Printed in One Piece

Thin Walls

History

Typically, Thales Alenia Space manufactures this type of antenna in multiple parts. Then, each piece is bonded or bolted together in complex and time-costly steps. While making precise components is not so difficult, assembling them into a precise antenna is time-consuming and has major impacts on global lead time and throughput for serial production. This is why Thales turned to additive manufacturing as a solution.

Challenge

Develop a 325mm diameter antenna with a 1mm wall thickness through additive manufacturing, ensuring minimal distortions and a surface finish that meets ‘ready-to-fly’ standards without requiring post-processing. By meeting these standards, TAS will be positioned to achieve a Technology Readiness Level (TRL) 3 for additive manufactured Cassegrain antennas.

Solution

AddUp worked closely with Thales Alenia Space to provide a counter-deformed simulation.

First a lightweight design was generated around initial specifications: main and sub reflectors surfaces, available design space, interfaces localization. Next, an isogrid structure was designed at the back of the main reflector to add stiffness to the system. Then a numerical simulation was done to anticipate the distortions of the antenna during the production.

Finally, a counter-deformed file is obtained from the initial simulation. The goal is to adapt the original design in the opposite direction of the simulated distortions. During the production, the distortions due to the internal constraints and the counter-deformed design cancel each other, keeping the real part as close as possible to the original design.

In order to get the best surface finish, requiring minimal post-processing, AddUp and Thales Alenia Space used their ECSS-qualified recipe on the FormUp 350, in aluminum AS7.

The performance of this recipe, coupled with the machine’s full-field 4 lasers, also enable high productivity. Series production simulations carried out by AddUp show a production rate of more than 2 antennas per day per machine.

Results

The final design achieved a lightweight antenna, weighing just 385 grams. The isogrid structure was meticulously optimized to minimize weight by varying the sizes around the reflector, thereby reinforcing only the necessary areas. The connecting arms between the main reflector and the sub-reflector were engineered and designed to minimize coupling effects in near field, optimizing overall antenna far field radiated performances. The distortions were successfully minimized, with a deviation of ±0.3mm over 90% of the antenna, which was well-received by both parties involved. Additionally, the global surface finish and roughness met the target of Ra 6.3 for both reflectors, achieving a completely satisfactory result.

Learn about Thales 3D Morocco’s FormUp 350 ECSS Qualification here.

An additively manufactured camera support, designed to withstand acceleration and vibration during launch to space and to hold a camera and its lens in position during the production phases of a metal 3D printer.

“Metal3D“ project objective is to characterize the mechanical properties of a material shaped in microgravity. To carry out this experiment, two batches of test specimens are being produced by the same printer design. While the first batch will be produced in Toulouse in terrestrial gravity, the second will be built in space, more precisely in the Columbus module of the ISS (International Space Station), in microgravity.

Mission

“Metal3D“ is a mission commissioned by ESA (European Space Agency) as a technology demonstrator. Its objective is to characterize the mechanical properties of a material shaped in microgravity. To carry out this experiment, two batches of test specimens are being produced by the same printer design. While the first batch will be produced in Toulouse in terrestrial gravity, the second will be built in space, more precisely in the Columbus module of the ISS (International Space Station), in microgravity. To produce these two prints, we have designed and manufactured two identical copies of a metal 3D printing machine capable of operating in both environments. The printer we have designed for this mission will therefore be the first to print metal parts in space.

Process

In the absence of gravity, the majority of current additive manufacturing processes are no longer usable. To make microgravity manufacturing possible, we choose to exploit the forces induced by surface tension. We use a laser as the energy source and steel wire as the raw material. The laser heats the substrate to create a liquid bath. In this liquid bath, we immerse the steel wire. By pushing the wire into the liquid bath, the latter also liquefies and increases the volume of the fusion bath. We then move the laser and therefore the liquid bath to the surface of the substrate while unwinding the wire in this bath so as to create a bead once the liquid bath has solidified. A layer is made up of one or more beads depending on the geometry of the part to be produced. Once the layer is finished, the process starts again using the previous layer as a substrate. In this way, layer by layer, a volumetric part is created.

For the process, we use a 316L wire. The laser and wire are fixed in the machine frame, it is the tabletop that is made mobile through 3 linear axes and 1 rotary axis. The machine is operated under nitrogen in order to limit the oxidation of the material and prevent the risk of combustion. As the access to nitrogen is limited in the ISS, this atmosphere is recycled throughout the manufacturing process by filtration and cooling.

Partners

The mission is being piloted by the Airbus Defense & Space teams. Cranfield University provides the laser, the optical chain, and the wire supply system to the system. Hightech provides the machine enclosure, which provides a sealed and cooling system, and the interfaces between the machine and the rack to which it is connected. Airbus, in addition to piloting the project, is managing the electronic and safety aspects of the machine.

On the mechanical side, AddUp is in charge of the internal structure and the mobile part of the machine. AddUp also manages the control board and the sensors that monitor the process. On the software side, AddUp has developed the machine’s PLC. This software has several functions, it allows communication with the ground by sending different types of data (measurements, photos, reports, etc.) from the machine and by executing the commands it receives.