Researchers from the Chemnitz University of Technology in Germany presented a fully 3D printed electric motor for the first time last week at Hannover Messe 2018. 3D printed from a combination of metallic and ceramic pastes, the electric motor is the first of its kind.
The 3D printed motor project was undertaken by two researchers from the Chemnitz University of Technology Professorship of Electrical Energy Conversion Systems and Drives: Johannes Rudolph and Fabian Lorenz. Working under Prof. Dr. Ralf Werner, the head of the Professorship, the researchers have been exploring the potentials of 3D printed electrical components for some time now.
Last year, the pair successfully 3D printed a coil capable of withstanding temperatures of over 300°C. Now, as visitors of Hannover Messe 2018 got to see first hand, they have created an electric motor made up entirely of 3D printed components. The motor itself consists of copper electrical conductors that create magnetic fields when combined with iron or iron alloys and a ceramic electrical insulation.
The 3D printed ceramic components not only keep the conductors insulated from each other and from the iron components—otherwise known as the “magnetic circuit”—but they have also allowed the researchers to significantly increase the temperature resistance of the 3D printed electrical machines. That is, by replacing polymer-based insulation materials with ceramics, the motor is capable of withstanding much higher temperatures than before.
“The maximum permissible winding temperature of 220°C associated with conventional insulation systems can then be exceeded by a significant amount,” explained Rudolph. “The operating temperature of electric machines is therefore only limited by the ferromagnetic properties of the iron components, which can only be maintained up to 700°C.”
In addition to their high temperature resistance, the ceramic materials used for the insulation components of the electric motor also provide a high degree of thermal conductivity, which allows for the heat loss generated in the conductors to be dissipated at faster rates. In practice, this feature enabled the researchers to increase the output density of the electrical machines.
“Despite the process-related decrease in the conductivity of the copper used, in specific application scenarios, it is possible to increase the degree of efficiency by significantly reducing the winding temperature,” said Lorenz.
The multimedia 3D printing method used by the Chemnitz research team consists of extruding a combination of highly viscous pastes in a layer by layer fashion. Each of the pastes used is made up of particles of a certain material (such as copper, iron and ceramics) as well as a specially-adapted binding agent. The highly viscous materials are then precisely deposited using an extrusion system developed in partnership with ViscoTec, a comany located in the Bavarian town of Töging am Inn that specializes in pumping and dosing systems for highly viscous fluids.
Once a part has been printed using the multi-material 3D printer, the component is subjected to a sintering heat treatment. The post-processing step effectively burns the binder material away and fuses the metal and ceramic materials together, resulting in a tough and durable part. The researchers do point out that the printed component will shrink during the sintering process, so CAD designs must account for this discrepancy.
Eventually, the German researchers hope to introduce their innovative 3D printing method onto the market. “The motor that was printed in the Chemnitz University Laboratory represents a breakthrough and is at the same time the proof of principle—it demonstrates the feasibility—of our technology,” said Rudolph. In fact, Rudolph and Lorenz are even planning to launch a university spin-off company to further accelerate their electrical additive manufacturing system. We’ll be keen to this project taken to the next level.