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26 April, 2018

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Spray-formed magnets could cut electric motor costs

05 February, 2018

Two Canadian researchers have developed a new method of producing magnets for electric motors which, they claim, could lead to significant cost reductions, as well as leading to designs that are impossible using traditional magnet manufacturing techniques. Fabrice Bernier and Jean-Michel Lamarre, from the National Research Council of Canada (NRC), add that magnets produced using their robot-controlled “cold-spray additive manufacturing” process have good mechanical and thermal properties.

The high-performance magnets used in electric motors today are typically made using processes such as powder compaction (for sintered magnets) or injection moulding (for bonded magnets). In these processes, the magnets first need to be fabricated, before being shaped and assembled into a final product. The NRC technology combines these steps into one.

In the cold-spray additive manufacturing process, a fine powder material is accelerated to supersonic speeds in a high-velocity compressed gas jet. As the stream of powder hits a target at high speed, the particles undergo a plastic deformation and adhere to the surface, building up layer upon layer. To control the process, an industrial robot performs rapid and precise 3D movements, allowing complex shapes to be created. Compared to other additive manufacturing technologies, the cold spray technique results in high build-up rates that can produce several kilograms of magnets every hour.

The high velocities used to deposit the material, and the absence of polymer in the material matrix, combine to give the magnets mechanical properties claimed to be “far superior” to those of conventional magnets. The adhesion of the magnetic material to the surface of the part is “exceptional”, because the process uses neither glue nor assembly.

Magnets created using the cold-spray process are easy to machine compared to more brittle sintered magnets. They also exhibit increased thermal conductivity, allowing better temperature control. The magnets are corrosion- and oxidation-resistant, and should last longer.

The Canadian researchers have successfully built and tested prototypes using the new magnetic material. They are now looking at other ways of using cold-spray additive manufacturing to enhance motor designs, and are also developing soft magnetic materials.

NRC researchers Jean-Michel Lamarre and Fabrice Bernier with a product made using their magnet manufacturing technology

According to Bernier, the NRC 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”.

To date, much of the NRC’s development work has focused on electric motors, because of the importance of reducing CO2 emissions in the next generation of vehicles. But the researchers believe that other industries could also benefit from their technology. Areas for future applications could include magnetic cooling, wind turbines and telecommunication devices.

A video of the magnet-manufacturing process can be seen here




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