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Magnetic coupling at elevated temperatures

Magnetic couplings are used in many applications within pump, chemical, pharmaceutical, process and security industries. They are usually used with the aim of decreasing wear, sealing of liquids from the surroundings, cleanliness needs or as a safety issue to brake over if torque abruptly rises.
The most typical magnetic couplings are made with an outer and inside drive, each construct up with Neodymium magnets to find a way to get the highest torque density as possible. By optimizing the diameter, air gap, magnet size, variety of poles and selection of magnet grade, it is attainable to design a magnetic coupling that fits any application in the range from few millinewton meter up to a quantity of hundred newton meters.
When solely optimizing for top torque, the designers often are likely to forget considering the influence of temperature. If the designer refers to the Curie level of the person magnets, he’ll declare that a Neodymium magnet would fulfill the requirements as a lot as greater than 300°C. Concurrently, it is important to include the temperature dependencies on the remanence, which is seen as a reversible loss – typically round 0,11% per diploma Celsius the temperature rises.
Furthermore, a neodymium magnet is under stress throughout operation of the magnetic coupling. This means that irreversible demagnetization will happen long before the Curie point has been reached, which generally limits the use of Neodymium-based magnetic coupling to temperatures beneath 150°C.
If higher temperatures are required, magnetic couplings made from Samarium Cobalt magnets (SmCo) are typically used. SmCo just isn’t as strong as Neodymium magnets but can work up to 350°C. Furthermore, the temperature coefficient of SmCo is just 0,04% per diploma Celsius which implies that it could be used in purposes where efficiency stability is needed over a bigger temperature interval.
New era In collaboration with Copenhagen Atomics, Alfa Laval, Aalborg CSP and the Technical University of Denmark a model new technology of magnetic couplings has been developed by Sintex with help from the Danish Innovation Foundation.
The function of the challenge was to develop a magnetic coupling that might broaden the working temperature space to succeed in temperatures of molten salts round 600°C. By exchanging pressure gauge 10 bar with a magnetic material containing a better Curie point and boosting the magnetic area of the outer drive with particular magnetic designs; it was attainable 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 perform of temperature. This resulted in superior efficiency above 160°C, regardless of if the benchmark was in opposition to a Neodymium- or Samarium Cobalt-based system. This could be seen in Figure 1, where it is proven that the torque level of the High Hot drives has been tested as a lot as 590°C on the inside drive and nonetheless carried out with an almost linear reduction in torque.
The graph also reveals that the temperature coefficient of the High Hot coupling is even lower than for the SmCo-system, which opens a lower temperature market the place performance stability is necessary over a larger temperature interval.
Conclusion At Sintex, the R&D division is still developing on the technology, however they must be challenged on torque degree at either different temperature, dimensions of the magnetic coupling or new functions that have not beforehand been attainable with standard magnetic couplings, to have the ability to harvest the complete potential of the High Hot expertise.
The High Hot coupling is not seen as a standardized shelf product, however as an alternative as custom-built by which is optimized for particular purposes. Therefore, further growth might be made in shut collaboration with new companions.