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Magnetic coupling at elevated temperatures

Magnetic couplings are used in many functions inside pump, chemical, pharmaceutical, process and safety industries. They are usually used with the purpose of decreasing wear, sealing of liquids from the surroundings, cleanliness wants or as a safety factor to brake over if torque suddenly rises.
The commonest magnetic couplings are made with an outer and inside drive, both construct up with Neodymium magnets to be able to get the very best torque density as potential. By optimizing the diameter, air hole, magnet size, number of poles and selection of magnet grade, it is attainable to design a magnetic coupling that suits any application in the range from few millinewton meter as a lot as a quantity of hundred newton meters.
When only optimizing for prime torque, the designers usually tend to neglect contemplating the influence of temperature. If the designer refers to the Curie point of the individual magnets, he’ll claim that a Neodymium magnet would fulfill the necessities as a lot as more than 300°C. Concurrently, you will want to embrace the temperature dependencies on the remanence, which is seen as a reversible loss – usually round 0,11% per degree Celsius the temperature rises.
Furthermore, a neodymium magnet is beneath pressure during operation of the magnetic coupling. This signifies that irreversible demagnetization will occur lengthy before the Curie point has been reached, which usually limits the use of Neodymium-based magnetic coupling to temperatures under 150°C.
If greater temperatures are required, magnetic couplings made from Samarium Cobalt magnets (SmCo) are usually used. SmCo is not as strong as Neodymium magnets but can work up to 350°C. Furthermore, เพรสเชอร์เกจ of SmCo is simply 0,04% per degree Celsius which signifies that it can be utilized in purposes where efficiency stability is required over a bigger temperature interval.
New technology In collaboration with Copenhagen Atomics, Alfa Laval, Aalborg CSP and the Technical University of Denmark a brand new technology of magnetic couplings has been developed by Sintex with assist from the Danish Innovation Foundation.
pressure gauge 10 bar of the venture was to develop a magnetic coupling that might broaden the working temperature area to achieve temperatures of molten salts around 600°C. By exchanging the inner drive with a magnetic materials containing a better Curie point and boosting the magnetic field of the outer drive with particular magnetic designs; it was attainable to develop a magnetic coupling that started at a decrease torque degree at room temperature, but solely had a minor discount in torque level as a function of temperature. This resulted in superior efficiency above 160°C, irrespective of if the benchmark was towards a Neodymium- or Samarium Cobalt-based system. This may be seen in Figure 1, the place it is shown that the torque level of the High Hot drives has been tested as a lot as 590°C on the inner drive and still carried out with an nearly linear discount in torque.
The graph also exhibits 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 efficiency stability is essential over a larger temperature interval.
Conclusion At Sintex, the R&D division is still creating on the know-how, however they need to be challenged on torque degree at either completely different temperature, dimensions of the magnetic coupling or new purposes that haven’t previously been attainable with standard magnetic couplings, to find a way to harvest the complete potential of the High Hot know-how.
The High Hot coupling just isn’t seen as a standardized shelf product, however instead as custom-built by which is optimized for specific functions. Therefore, additional improvement shall be made in close collaboration with new companions.