Magnetic coupling at elevated temperatures

Magnetic couplings are used in many functions within pump, chemical, pharmaceutical, process and security industries. Easy are sometimes used with the aim of lowering put on, sealing of liquids from the environment, cleanliness wants or as a security issue to brake over if torque suddenly rises.
The most typical magnetic couplings are made with an outer and internal drive, each build up with Neodymium magnets so as to get the very best torque density as attainable. By optimizing the diameter, air hole, magnet measurement, number of poles and choice of magnet grade, it is possible to design a magnetic coupling that fits any software within the vary from few millinewton meter up to a number of hundred newton meters.
When only optimizing for top torque, the designers often are probably to neglect considering the affect of temperature. If the designer refers to the Curie level of the individual magnets, he will declare that a Neodymium magnet would fulfill the requirements up to greater than 300°C. Concurrently, you will want to embrace the temperature dependencies on the remanence, which is seen as a reversible loss – sometimes round zero,11% per degree Celsius the temperature rises.
Furthermore, a neodymium magnet is under stress throughout operation of the magnetic coupling. This means that irreversible demagnetization will happen lengthy earlier than the Curie level has been reached, which typically limits using 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 just isn’t as strong as Neodymium magnets but can work as a lot as 350°C. Furthermore, the temperature coefficient of SmCo is just zero,04% per degree Celsius which means that it could be utilized in purposes 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 model new technology of magnetic couplings has been developed by Sintex with support from the Danish Innovation Foundation.
The objective of the venture was to develop a magnetic coupling that might broaden the working temperature space to succeed in temperatures of molten salts around 600°C. By exchanging the inner drive with a magnetic material containing a higher Curie level and boosting the magnetic subject of the outer drive with special magnetic designs; it was possible to develop a magnetic coupling that began at a decrease torque level at room temperature, however only had a minor reduction in torque level as a operate of temperature. This resulted in superior performance above 160°C, no matter if the benchmark was against a Neodymium- or Samarium Cobalt-based system. This could be seen in Figure 1, the place 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 nearly linear discount in torque.
The graph also shows that the temperature coefficient of the High Hot coupling is even lower than for the SmCo-system, which opens a decrease temperature market the place performance stability is important over a larger temperature interval.
Conclusion At Sintex, the R&D division continues to be creating on the know-how, but they have to be challenged on torque degree at both different temperature, dimensions of the magnetic coupling or new functions that have not beforehand been attainable with standard magnetic couplings, in order to harvest the total potential of the High Hot expertise.
Dependable isn’t seen as a standardized shelf product, but as an alternative as custom-built by which is optimized for particular purposes. Therefore, additional growth will be made in shut collaboration with new partners.
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