AddUp, Cébazat, France, is part of the Metal3D project which intends to create a point-of-need metal Additive Manufacturing machine for use in space. The project, led by the European Space Agency (ESA), Airbus Defense and Space, and other industrial & academic partners, intends to have parts manufactured on board the International Space Station (ISS) Columbus module by February 2023.
Metal3D was commissioned by the ESA as a technology demonstrator which can enable the characterisation of the mechanical properties of a material shaped in microgravity. To carry out this experiment, two batches of test specimens will be produced by two identical Additive Manufacturing machines. The first batch will be made in Toulouse, France, in terrestrial gravity and the second will be built in space, in microgravity.
To produce these two Additive Manufacturing projects, two identical copies of a metal Additive Manufacturing machine capable of operating in both environments have been designed and produced. The resultant machine will therefore be the first to manufacture metal parts in space.
Project management is provided by the Airbus Defense and Space teams in Toulouse; these aim to ensure the integration of the various components of the Additive Manufacturing machine, the power supply, and the conformity for the space environment. Academic partner Cranfield University oversees the energy source and material delivery mechanism, including laser and stainless-steel wire.
The company Highftech is tasked with the manufacturing of the machine enclosure and integrating the machine’s fluid management, while AddUp makes the internal structure & mechanisms of the machine, the PLC that controls it, and the interface that allows communication with the ground. On the mechanical side, AddUp’s team designed and manufactured the internal structure of the machine, including all moving parts. On the software side, the team developed the machine’s automation programme, which includes functions such as communication with the ground (data transfer, measurements, images & reports, and execution of commands received from Earth).
“AddUp plays an important role in the realisation of this mission, but its involvement in the project goes back to the pre-project phase where the feasibility of the project had to be demonstrated,” stated Alexandre Piaget, R&D engineer at AddUp. “This first part, carried out on the premises in Salon de Provence, built the foundations of what the machine is today. In the final version of the machine, AddUp is in charge of the mobile axes, the structural parts and the software of the machine.”
In the absence of gravity, most current Additive Manufacturing processes are rendered obsolete. This is either because they are not compatible with the space environment (the use of fine powder is dangerous in the space station), or because their implementation is conflicting with microgravity (e.g., Powder Bed Fusion). To make manufacturing in microgravity possible, the partners have chosen to use a process that promotes forces induced by surface tension: wire-based Directed Energy Deposition.
In this process, a laser will be used as the energy source with 316L stainless steel wire as the raw material. The laser and the wire feeding system are fixed in the machine frame and the build table is made movable by three linear axes and one rotary axis. The machine is operated under nitrogen to limit the oxidation of the material and to prevent the risks of combustion. As access to nitrogen is limited in the ISS, the machine’s atmosphere is filtered and cooled throughout the manufacturing process to limit nitrogen consumption and recycle as much as possible of the nitrogen already present in the machine.
A video of the project is available here.