Magnetic coupling at elevated temperatures

Magnetic couplings are utilized in many functions within pump, chemical, pharmaceutical, process and safety industries. They are usually used with the aim of reducing wear, sealing of liquids from the surroundings, cleanliness needs or as a security factor to brake over if torque all of a sudden rises.
The most typical magnetic couplings are made with an outer and inside drive, each construct up with Neodymium magnets in order to get the very best torque density as potential. By optimizing the diameter, air gap, magnet dimension, number of poles and choice of magnet grade, it’s attainable to design a magnetic coupling that fits any application within the range from few millinewton meter as much as a number of hundred newton meters.
When solely optimizing for high torque, the designers typically are most likely to forget contemplating the affect of temperature. If the designer refers to the Curie point of the person magnets, he’ll declare that a Neodymium magnet would fulfill the necessities up to greater than 300°C. Concurrently, it is essential to embody the temperature dependencies on the remanence, which is seen as a reversible loss – typically round zero,11% per diploma Celsius the temperature rises.
Furthermore, a neodymium magnet is beneath stress during operation of the magnetic coupling. This signifies that irreversible demagnetization will occur lengthy earlier than the Curie point has been reached, which generally limits the utilization of Neodymium-based magnetic coupling to temperatures under 150°C.
If Smooth are required, magnetic couplings made of Samarium Cobalt magnets (SmCo) are typically used. SmCo is not as sturdy as Neodymium magnets but can work up to 350°C. Furthermore, the temperature coefficient of SmCo is simply 0,04% per degree Celsius which means that it may be used in applications where efficiency stability is required over a larger temperature interval.
New era In collaboration with Copenhagen Atomics, Alfa Laval, Aalborg CSP and the Technical University of Denmark a new era of magnetic couplings has been developed by Sintex with assist from the Danish Innovation Foundation.
The function of the venture was to develop a magnetic coupling that might increase the working temperature space to succeed in temperatures of molten salts around 600°C. By exchanging the inner drive with a magnetic materials containing a better Curie level and boosting the magnetic subject of the outer drive with particular magnetic designs; it was potential to develop a magnetic coupling that began at a decrease torque stage 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, regardless of if the benchmark was towards a Neodymium- or Samarium Cobalt-based system. This could be seen in Figure 1, the place it is shown that the torque stage of the High Hot drives has been examined as much as 590°C on the inside drive and still performed with an virtually linear discount in torque.
Template reveals that the temperature coefficient of the High Hot coupling is even decrease than for the SmCo-system, which opens a lower temperature market where efficiency stability is necessary over a larger temperature interval.
Conclusion At Sintex, the R&D department remains to be growing on the expertise, however they must be challenged on torque degree at either different temperature, dimensions of the magnetic coupling or new applications that haven’t beforehand been possible with standard magnetic couplings, so as to harvest the full potential of the High Hot technology.
The High Hot coupling is not seen as a standardized shelf product, however as a substitute as custom-built by which is optimized for particular applications. Therefore, further growth might be made in shut collaboration with new companions.

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