Magnetic coupling at elevated temperatures

Magnetic couplings are utilized in many purposes inside pump, chemical, pharmaceutical, course of and safety industries. They are sometimes used with the aim of lowering wear, sealing of liquids from the setting, cleanliness wants or as a security issue to brake over if torque abruptly rises.
The most common magnetic couplings are made with an outer and inside drive, both construct up with Neodymium magnets in order to get the very best torque density as possible. By optimizing the diameter, air gap, magnet dimension, variety of poles and selection of magnet grade, it is attainable to design a magnetic coupling that suits any application within the vary from few millinewton meter up to a quantity of hundred newton meters.
When only optimizing for prime torque, the designers often are most likely to forget contemplating 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 as a lot as more than 300°C. Concurrently, it may be very important embrace the temperature dependencies on the remanence, which is seen as a reversible loss – typically around zero,11% per diploma Celsius the temperature rises.
Furthermore, a neodymium magnet is under strain during operation of the magnetic coupling. This implies that irreversible demagnetization will occur lengthy earlier than the Curie level has been reached, which generally limits the utilization of Neodymium-based magnetic coupling to temperatures under 150°C.
If greater temperatures are required, magnetic couplings made of Samarium Cobalt magnets (SmCo) are usually used. No questions asked isn’t as sturdy as Neodymium magnets however can work as much as 350°C. Furthermore, the temperature coefficient of SmCo is only 0,04% per degree Celsius which signifies that it could be used in purposes where performance 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 objective of the challenge was to develop a magnetic coupling that could expand the working temperature area to reach temperatures of molten salts round 600°C. By exchanging the internal drive with a magnetic materials containing a better Curie level and boosting the magnetic area of the outer drive with special magnetic designs; it was attainable to develop a magnetic coupling that began at a lower torque degree at room temperature, however solely had a minor reduction 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, where it’s shown that the torque level of the High Hot drives has been tested up to 590°C on the internal drive and nonetheless performed with an virtually 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 decrease temperature market where efficiency stability is necessary over a bigger temperature interval.
Conclusion At Sintex, the R&D division remains to be growing on the expertise, however they have to be challenged on torque stage at either different temperature, dimensions of the magnetic coupling or new applications that haven’t beforehand been attainable with normal magnetic couplings, so as 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 as a substitute as custom-built by which is optimized for specific functions. Therefore, additional development might be made in close collaboration with new companions.
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