Process uses copper, iron, and ceramic pastes

By Heather Hamilton, contributing writer

Since 2012, Chemnitz
University of Technology in Germany has actively researched additive
manufacturing for electric motors. By layering and then sintering the
materials, researchers have successfully manufactured all required motor
components in a lab through a proprietary 3D-printing process that utilizes copper,
iron, and ceramic pastes.

Stators of the first 3D-printed electric machine. Photo: TU Chemnitz/Jacob Müller.

These include “copper electrical conductors,
which create magnetic fields in combination with iron or iron alloys and
ceramic electrical insulation, which insulates the conductors from each other
and from the iron components,” said the researchers.

 

Doctor and professor Ralf Werner and research assistants
Johannes Rudolph and Fabiana Lorenz initially presented a 3D coil in 2017,
which was capable of withstanding temperatures over 300°C. “The goal of
about two and a half years of work has been to shift the limit of the operating
temperature of electrical machines significantly upwards,” Werner said in a press
release
.

 

According to researchers, viscous pastes are
extruded through a die that builds the 3D-body in layers, offset with
specialized binders (which are later expelled as the metallic and ceramic
particles fuse together) depending on the body shape of the printed material.
The researchers add that the reduction in volume must be considered when building
the CAD data, and that the heat treatment results in a solid body with low
residual porosity.

 

The 3D multi-material process allows for several
materials to be used simultaneously while something is being printed, which
provides for a greater variety of desirable characteristics like heat
resistance and thermal conductivity. The process also allows for
self-supporting structures, which means that it can be used to print structures
with both closed and empty cavities, which can allow for passive and active
cooling.

The use of ceramic
materials, as opposed to more traditional polymer-based, affords a greater
temperature resistance in which the upper temperature limit — at up to 700°C
—  is set by the iron.

 

“Despite a
process-related, slightly reduced electrical conductivity of the copper, it is
also possible in special applications to increase the efficiency by
significantly reducing the winding temperature,” Lorenz said in a press release.

Researchers said with the addition of additional support
structures, they’ll be able to print almost any 3D shape with high material
efficiency. And, while the team presented additional details at Hannover Messe in
April, they’re now developing the motor for series production for use in
engineering, automotive, and aviation industries.