A number of researchers are exploring the use of 3D printing/additive manufacturing in space applications. One experiment is testing the possibility of using 3D printing to make spacecraft components directly in orbit. The Additive Manufacturing In Space (AIMIS-FYT) team at Munich University of Applied Sciences is developing and researching an additive manufacturing process in which the production of structures takes place in zero gravity. The benefit here is that elements produced this way for space travel do not have to meet the high launch requirements. The process is being researched on parabolic flights in zero gravity – supported by a uEye CP industrial camera from IDS.

For this additive manufacturing process, the AIMIS-FYT team developed a 3D printer with an extruder that dispenses a liquid photopolymer.

“Our 3D printing process can directly print three-dimensional structures in space using a UV-curing adhesive or potting compound,” says Torben Schaefer, press officer of the AIMIS-FYT team.

Rather than create components layer by layer, the team created a 3D printer that builds parts directly using the three-dimensional movement of the print head. UV light cures the resin that is freely extruded into space in zero gravity, hardening the material in a short time.

In combination with weightlessness, this process enables manufacturing without shape restrictions that normally exist due to gravity on Earth. Typical shape limitations are, for example, long overhangs that are not possible on earth or that can only be manufactured with elaborate support structures. In zero gravity, it is even possible to create components without a fixed anchor point, such as a pressure plate.

This production process enables a variety of designs, such as printed structures for solar panels or antennas. For example, the production of mirrors for parabolic antennas or the manufacture of truss structures for the mounting of solar generators is possible. Those who develop small and micro-satellites or even entire satellite constellations can make them in orbit, rather than on Earth, reducing unit and launch costs for transporting their systems into orbit. Building satellites in space also enables developers to take more fuel on board, extending the useful life.

“For satellites, the fuel is usually the limiting factor; at present, it usually lasts for around 15 years,” explains Torben Schaefer.

One of the first tests was the printing of straight rods, connections of rods and the creation of free-form rods. In one case, a conventional printing plate was used as the starting point for printing; in another case, the behavior of printing, free-floating rods were investigated.

The 3D printing process
The main parameters of the printing process are the extrusion speed of the resin, the UV light intensity, the UV light time and the trajectory– or the movement path of the printer.

“In our printing process, precise, pressure-stable and constant delivery of the medium is important. At the same time, the parameters should be kept constant during the entire process,” says Torben Schaefer. The USB 3 camera sponsored by IDS keeps a close eye on the process: It watches the nozzle of the printer in close-up and always moves relative to it. This way, the camera follows the nozzle with every movement. The image is cropped in such a way that the formation of the rods is captured around 4.5 cm below the nozzle.

“The IDS camera provides important results for the discharge of the resin and its curing. The UV LEDs produce a strong overexposure, which means that difficult lighting conditions exist. These are no problems for the U3-3260CP from the IDS portfolio: with the cost-effective 2.30 MPixel Sony sensor IMX249 (1920 x 1200 px). It makes the global shutter CMOS sensor with its 5.86 µm pixels predestined for applications like these, which are supposed to deliver a perfect result even in difficult lighting conditions – in this case, strong brightness due to overexposure.

To further analyze the exit behavior from the nozzle in zero gravity, the process is carried out at a slower speed. The contour of the rod must be precisely captured.

“For this, the high frame rate and resolution of the camera are crucial for a high-quality evaluation,” says Torben Schaefer from the AIMIS team. With a frame rate of 47.0 fps, the IDS camera ensures good image quality with minimal noise – perfect conditions for its task in space.

In addition, the camera was easy to install.

“We were able to seamlessly integrate the camera into our C++-based monitoring system with the help of the IDS SDK,” says Torben Schäfer. According to him, this is where all the data from the sensors converge and provide a comprehensive overview of the current status of the printer and the individual print parameters.

“We can start and stop the recording of the IDS camera and all other measurements with one click. Since there are only twenty seconds of zero gravity on a parabolic flight and there is a break of around one and a half minutes between two parabolas, we only save the most important information by starting and stopping measurements and recordings in a targeted manner.” In addition, a live image of the printing process is displayed on the monitor with the help of the IDS software. “This live feed makes it easier for us to set up and quickly analyze the printhead.”

Outlook
The findings from the experiments will be used to further optimize the printing process of the four basic 3D printing operations (straight bar, straight bar with start/stop points, free-form bar as well as connections between bars) and to prove the primary function of additive manufacturing in zero gravity. The aim is to test the technology in space, as it offers the chance to drastically reduce the cost of components in space technology.

“With the AIMIS-FYT project, we have the opportunity to actively shape the future of space travel,” says Michael Kringer, project manager of the AIMIS-FYT team. The powerful little IDS camera has successfully recommended itself for future missions – on Earth and in space.

IDS Imaging Development Systems GmbH
en.ids-imaging.com