Complete electric motors produced in 3D printing
Researchers at the Chemnitz University of Technology succeeded in printing complete electric motors with the aid of metallic and ceramic pastes, which are formed in layers by an extrusion process and then sintered. Last year, the same team already presented a 3D printed coil that can withstand temperatures of over 300°C. In the meantime, they managed to produce all relevant components of an electric machine in one 3D multi-material printing process. These include electrical conductors made of copper, which, together with iron or ferrous alloys, cause the formation and alignment of magnetic fields as well as the electrical insulation made of ceramic, which insulates the conductors against each other and against the magnetic circuit parts made of iron.
The aim of the approximately two-and-a-half years of work has so far been to push the limit on the operating temperature of electrical machines upwards. The researchers achieved this goal by replacing the conventional polymer-based insulation materials with ceramics with a much higher temperature resistance. The permissible winding temperature of conventional insulation systems of up to 220°C can thus be significantly exceeded, so that the operating temperature of electrical machines is only limited by the ferromagnetic properties of the iron, which remain intact up to 700°C.
In addition to the higher temperature resistance, the ceramic insulation material also has a higher thermal conductivity. As a result, the heat loss in the conductors can be dissipated faster. In this way, the scientists achieve another important goal of their work: increasing the power density of electrical machines. “Despite a process-related, slightly reduced electrical conductivity of the copper, it is also possible to increase efficiency in special applications by significantly reducing the winding temperature,” explains Fabian Lorenz, a research assistant at the Technical University of Chemnitz.
The basis of the process, which the researchers now intend to further develop to market maturity, is the extrusion of high-viscosity pastes layer by layer. These contain particles of the desired materials such as iron, copper or ceramics and specially tailored binders. In order to achieve the precision required for multi-material printing, the scientists work together with dosing technology company ViscoTec Pumpen- u. Dosiertechnik GmbH.
“The motor printed in the Chemnitz University laboratory represents a breakthrough and is also the proof of principle for our technology,” assures scientist Johannes Rudolph, who was instrumental in the development of the process and who, together with Lorenz, is preparing a spin-off from the university. As the next step, the scientists will be presenting their world premiere at the Hanover Fair from 23 to 27 April 2018 at the joint “Research for the Future” stand in Hall 2, Stand A38.
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