The National Research Council of Canada (NRC) reports to have produced permanent magnets for electric motors using cold spray additive manufacturing. This manufacturing technique allows permanent magnets to be produced faster, making the magnets cheaper. In addition, the production method enables new designs of permanent magnets with more complex shapes.
The operation of an electric motor is based on electromagnetism. The motor consists of a stator and a rotor equipped with a number of coils. These coils rotate in a magnetic field generated using two permanent magnets. The force action of the magnetic poles on each other makes the rotor in the electric motor rotate.
Production of magnets
Magnets for electric motors are typically produced through processes such as powder compaction for sintered magnets or injection moulding for bonded magnets. In these processes, magnets are first produced and shaped, after which they are assembled into a final product. Cold spray additive manufacturing speeds up this process by combining these different steps into one process.
Cold spray additive manufacturing involves spraying a fine powder in a stream of gas at a high velocity onto a material, in this case the inside of a cylinder. This leaves the powder on the material, which makes it possible to build up an object layer by layer. By performing this process with great precision by an industrial robot, it is possible to create complex shapes using cold spray additive manufacturing.
Benefits of cold spray technology
Compared to other manufacturing methods, cold spray technology has a number of significant advantages. For instance, permanent magnets can be produced faster using the technology; the NRC reports being able to produce several kilograms of magnets per hour. In addition, the production method produces magnets with intrinsic mechanical properties that are superior to those of conventional magnets, according to the NRC. For instance, the adhesion of the magnetic material to a component is very strong, as the material is sprayed directly onto this component. Assembly is therefore not required.
In addition, magnets produced via cold spray additive manufacturing are less brittle than sintered magnets. This property makes it easier to machine the magnets. Also, cold spray additive manufacturing produces magnets that conduct heat better than traditional magnets, allowing better management of the temperature of the material. The magnets are resistant to both corrosion and oxidation, which increases the life of the magnets.
More compact and better presenting motors
"This technology enables the creation of more compact, higher performance motors for the future and paves the way for building complete motors using cold spray technology, offering significant benefits such as cost savings, better thermal management and more complex geometry and functionalities," explains Fabrice Bernier, a researcher at the NRC.
A video shows how the researchers use cold spray technology to apply a permanent magnet to the inside of a cylinder. This involves the use of an industrial robot.
Author: Wouter Hoeffnagel
Source: National Research Council of Canada
Source photo: Pixabay / PIRO4D
