Magnetic coupling at elevated temperatures

Magnetic couplings are utilized in many applications within pump, chemical, pharmaceutical, process and security industries. They are sometimes used with the aim of decreasing put on, sealing of liquids from the environment, cleanliness needs or as a security factor to brake over if torque suddenly rises.
The commonest magnetic couplings are made with an outer and inside drive, both build up with Neodymium magnets to find a way to get the best torque density as possible. By optimizing the diameter, air gap, magnet size, number of poles and selection of magnet grade, it’s possible to design a magnetic coupling that fits any utility in the vary from few millinewton meter as a lot as several hundred newton meters.
When only optimizing for top torque, the designers often are inclined to overlook contemplating the affect of temperature. If the designer refers to the Curie level of the individual magnets, he’ll declare that a Neodymium magnet would fulfill the necessities as much as greater than 300°C. Concurrently, it could be very important embody the temperature dependencies on the remanence, which is seen as a reversible loss – sometimes around 0,11% per diploma Celsius the temperature rises.
Furthermore, a neodymium magnet is under pressure during operation of the magnetic coupling. This means that irreversible demagnetization will occur long before the Curie point has been reached, which usually limits the usage of Neodymium-based magnetic coupling to temperatures beneath 150°C.
If larger temperatures are required, magnetic couplings manufactured from Samarium Cobalt magnets (SmCo) are typically used. SmCo isn’t as sturdy as Neodymium magnets but can work up to 350°C. Furthermore, the temperature coefficient of SmCo is only zero,04% per diploma Celsius which signifies that it can be utilized in applications the place efficiency stability is needed over a bigger temperature interval.
New technology In collaboration with Copenhagen Atomics, Alfa Laval, Aalborg CSP and the Technical University of Denmark a new technology of magnetic couplings has been developed by Sintex with support from the Danish Innovation Foundation.
The function of the project was to develop a magnetic coupling that could increase the working temperature space to achieve temperatures of molten salts around 600°C. By exchanging the internal drive with a magnetic materials containing a higher Curie level and boosting the magnetic area of the outer drive with particular magnetic designs; it was possible to develop a magnetic coupling that started at a decrease torque level at room temperature, however solely had a minor reduction in torque stage as a function of temperature. This resulted in superior efficiency above 160°C, no matter if the benchmark was in opposition to a Neodymium- or Samarium Cobalt-based system. This can be seen in Figure 1, where it’s proven that the torque level of the High Hot drives has been tested up to 590°C on the inside drive and still carried out with an nearly linear discount in torque.
The graph additionally reveals that the temperature coefficient of the High Hot coupling is even lower than for the SmCo-system, which opens a lower temperature market where performance stability is necessary over a bigger temperature interval.
Building blocks At Sintex, the R&D division is still developing on the know-how, however they need to be challenged on torque stage at both completely different temperature, dimensions of the magnetic coupling or new purposes that haven’t beforehand been attainable with normal magnetic couplings, so as to harvest the complete potential of the High Hot technology.
The High Hot coupling isn’t seen as a standardized shelf product, however instead as custom-built by which is optimized for specific applications. Therefore, further growth might be made in close collaboration with new companions.
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