Magnetic couplings are utilized in many applications within pump, chemical, pharmaceutical, course of and safety industries. They are usually used with the aim of decreasing wear, sealing of liquids from the environment, cleanliness wants or as a safety issue to brake over if torque suddenly rises.
The commonest magnetic couplings are made with an outer and inner drive, both build up with Neodymium magnets so as to get the best torque density as potential. By optimizing diaphragm seal , air gap, magnet dimension, number of poles and selection of magnet grade, it’s attainable to design a magnetic coupling that fits any software within the range from few millinewton meter up to several hundred newton meters.
When solely optimizing for top torque, the designers usually are likely to forget contemplating the influence of temperature. If the designer refers to the Curie point of the person magnets, he will declare that a Neodymium magnet would fulfill the requirements up to more than 300°C. Concurrently, it is very important embody the temperature dependencies on the remanence, which is seen as a reversible loss – sometimes around zero,11% per degree Celsius the temperature rises.
Furthermore, a neodymium magnet is underneath strain during operation of the magnetic coupling. This means that irreversible demagnetization will happen lengthy earlier than the Curie level has been reached, which typically 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 however can work up to 350°C. Furthermore, the temperature coefficient of SmCo is only 0,04% per degree Celsius which means that it could be used in purposes where efficiency stability is required over a larger temperature interval.
New generation 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 help from the Danish Innovation Foundation.
The objective of the challenge was to develop a magnetic coupling that would expand the working temperature space to reach temperatures of molten salts round 600°C. By exchanging the inner drive with a magnetic material containing a better Curie point 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 lower torque level at room temperature, however solely had a minor reduction in torque level as a function of temperature. This resulted in superior performance above 160°C, irrespective of if the benchmark was in opposition to a Neodymium- or Samarium Cobalt-based system. This may be seen in Figure 1, the place it is proven that the torque degree of the High Hot drives has been examined up to 590°C on the internal drive and nonetheless performed with an nearly linear discount 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 where efficiency stability is necessary over a bigger temperature interval.
Conclusion At Sintex, the R&D department continues to be growing on the technology, however they need to be challenged on torque degree at either different temperature, dimensions of the magnetic coupling or new functions that have not beforehand been possible with standard magnetic couplings, in order to harvest the total potential of the High Hot know-how.
The High Hot coupling isn’t 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 partners.
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