The high-performance magnets used in electric motors are typically made through processes like powder compaction, for sintered magnets, or injection molding for bonded magnets. These processes require multiple steps – the magnets need to first be fabricated and then shaped and assembled into a final product. But a pair of Canadian researchers have come up with a better way that combines all of those steps into one.
Fabrice Bernier and Jean-Michel Lamarre of the National Research Council (NRC) of Canada have developed a new process for fabricating magnets for electric motors. It’s called cold spray additive manufacturing, which involves a material in fine powder form being accelerated in a high-velocity compressed gas jet. A stream of powder hits the substrate at great speed and begins building up a layer at a time, creating complex shapes thanks to industrial robot control. Compared to other additive manufacturing technologies, cold spray additive manufacturing has extremely high buildup rates, allowing for the production of several kilograms of magnets per hour.
The magnets created using cold spray additive manufacturing have excellent mechanical and thermal properties – far superior to those of conventional magnets. The high velocities at which the material is deposited and the absence of polymer in the material matrix result in better mechanical properties, and the adhesion of the magnet to the part is also excellent, requiring neither glue nor assembly. Magnets created using cold spray additive manufacturing are also easy to machine compared to sintered magnets, which are more brittle.
In addition, magnets created with cold spray additive manufacturing technology have increased thermal conductivity, which allows for better temperature control. They’re also corrosion- and oxidation-resistant, meaning that they will have longer lifespans.
Prototypes using this new magnetic material have been tested successfully, and the NRC is looking into ways to use cold spray additive manufacturing to enhance motor designs. They are also working on the development of soft magnetic materials.
“This technology will allow the creation of more compact, better performing motors for the future and could pave the way for building entire motors using cold spray technology, offering significant advantages such as cost reduction, better thermal management and more complex geometries and functionalities,” said Bernier.
The NRC’s focus has been on electric motors, as technology urgently needs to be developed that can reduce carbon dioxide emissions from vehicles. However, this new method of fabricating magnets could lend itself to multiple other applications as well, such as magnetic cooling, wind turbines and telecommunications devices.
Other organizations have been working with cold spray technology as a form of additive manufacturing as well. Cold spray has been used for a long time to repair metal parts, but as it turns out, it works quite well as a means for fabricating new parts, too. Additive manufacturing is also increasingly coming into play for the development of superior permanent magnets.
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