3D printing component for the removal of "uncooperative" space debris

• What was needed: two NEMA 11 stepper motors, 3D-printed lead screw nut made of iglidur ® J260 tribofilament®, plastic sliding film Tribo-Tape made of iglidur® V400
• Manufacturing process: Filament extrusion (FDM)
• Requirements: Temperature & pressure resistance of the components, durable and lightweight design, reliable ejection mechanism
• Material: iglidur® J260
• Industry: Aerospace industry
• Success through cooperation: stepper motor and threaded spindle together with the plastic sliding film guarantee reliable ejection

The application at a glance:
In order to be able to successfully collect space debris, test data must first be collected on the movement of the parts in space. A team of six students from the University of Bremen and Bremen University of Applied Sciences has developed a rocket module that uses sensors and cameras to record the movement and position of objects in space using an ejected test body. Two parallel screw drives were used for the ejection mechanism. The screw drives were exposed to extreme loads, such as temperatures of +200 °C due to air friction, and had to function reliably. This is where the components from igus® came into play: The drylin® spindle drives were each driven by a NEMA 11 stepper motor. The holder for the test body was attached to a 3D-printed lead screw nut made from the tribofilament® iglidur® J260-PF. A plastic sliding film was used to ensure that the test body slipped out of the holder and moved away from the rocket.

In the UB-Space project, six students worked on the problem of "collecting" and disposing of space debris. In order to realise this project, however, the team led by Maren Hülsmann needed sufficient test data on the movement of objects in space. To do this, they wanted to eject a cube-shaped test object into the thermosphere and observe it with cameras and sensors in order to collect the necessary real data. The team needed reliable materials for the components of the ejection mechanism with which the object was to be dropped from the rocket. These had to fulfil the special requirements relating to space, such as limited installation space and weight, as well as energy consumption and good resistance to pressure and temperature.

With the materials from igus® optimised for sliding applications, the team quickly found suitable components for the planned ejection mechanism. This consisted of two NEMA 11 stepper motors, which in turn were each connected to a threaded spindle via a coupling. This construction was mounted on the rocket wall with a 3D-printed lead screw nut made of iglidur® J260-PF. The running surface of the ejection chute was lined with Tribo-Tape made of iglidur® V400 so that the test object could be ejected without friction.

It is not only on Earth that there is a major waste problem. With over 1,000 satellites orbiting the blue planet, there is also a lot of rubbish in space after decades of space travel. There are now more than 30,000 objects orbiting the Earth, which can be very dangerous for active satellites. These objects can reach speeds of up to 25,000 km/h and thus release highly destructive energies in the event of a collision. The aim of the UB-Space project is to collect the waste in space and dispose of it properly. The six-member interdisciplinary team consisting of students from the University of Bremen and Bremen University of Applied Sciences has set itself the task of analysing the movement of these so-called "uncooperative objects" in space in order to enable an appropriate waste collection campaign. For this purpose, a test body installed in a rocket module is released into the thermosphere. The position and movement of the so-called "Free Falling Unit" (FFU) is precisely recorded by sensors and a camera system after ejection, thus creating a real calculation basis for the team.

The UB-Space team developed a special mechanism for the rocket module in order to be able to reliably eject this FFU at the right time. However, the use of the mechanism in space differs significantly from normal missions on Earth. According to ship technology student Oliver Dorn, energy consumption, weight and installation space are all limited. In addition, the air friction results in temperatures of up to +200 °C. After several tests, the team decided in favour of a drive system consisting of two parallel threaded spindles that extend the unit in which the FFU is located. A flap, which is blasted off beforehand, serves as the opening for the unit. The stainless steel spindles from the igus® drylin® programme are each driven by a NEMA 11 stepper motor. They cover a distance of 150 millimetres at a high torque and low speed of 3 cm/s. The opposite side of the construction is mounted on the rocket wall with a 3D-printed lead screw nut made of iglidur® J260-PF. So that the FFU can be ejected as smoothly as possible, the ejection chute is lined with the Tribo-Tape plastic sliding film made of iglidur® V400. The materials from igus® are ideally suited for precisely this type of application, as their optimum sliding properties ensure tilt-free and energy-efficient ejection. They are also resistant to pressure and temperature and have a low weight, which was decisive for the special structural requirements.

In addition to the iglidur J260-PF tribofilament used, igus offers other filaments for 3D printing. As the name suggests, the filaments are tribologically optimised and suitable for any application where friction and wear are a concern. It is in just such applications that customers benefit from a long service life and temperature resistance of up to 180°C. The printing process allows complicated geometries to be produced in a single operation. The additive process is particularly well suited to special parts for prototypes or small volumes. The production costs are lower and there is therefore no minimum quantity.