Magnetic coupling at elevated temperatures

Magnetic couplings are used in many purposes inside pump, chemical, pharmaceutical, process and safety industries. They are typically used with the purpose of reducing wear, sealing of liquids from the environment, cleanliness needs or as a security issue to brake over if torque abruptly rises.
The most common magnetic couplings are made with an outer and inner drive, each build up with Neodymium magnets in order to get the very best torque density as attainable. By optimizing the diameter, air hole, magnet dimension, variety of poles and choice of magnet grade, it is possible to design a magnetic coupling that suits any software in the vary from few millinewton meter up to a quantity of hundred newton meters.
When solely optimizing for high torque, the designers typically are inclined to overlook considering the influence of temperature. If the designer refers back to the Curie level of the person magnets, he will declare that a Neodymium magnet would fulfill the requirements as a lot as more than 300°C. Concurrently, it is important to embody the temperature dependencies on the remanence, which is seen as a reversible loss – usually round zero,11% per degree Celsius the temperature rises.
Furthermore, a neodymium magnet is under strain during operation of the magnetic coupling. This implies that irreversible demagnetization will happen lengthy earlier than the Curie point has been reached, which typically limits using Neodymium-based magnetic coupling to temperatures below 150°C.
If larger temperatures are required, magnetic couplings made from Samarium Cobalt magnets (SmCo) are typically used. SmCo is not as sturdy as Neodymium magnets however can work up to 350°C. Furthermore, the temperature coefficient of SmCo is just zero,04% per diploma Celsius which implies that it might be used in purposes where efficiency stability is required over a larger temperature interval.
No strings attached In collaboration with Copenhagen Atomics, Alfa Laval, Aalborg CSP and the Technical University of Denmark a new generation of magnetic couplings has been developed by Sintex with support from the Danish Innovation Foundation.
The objective of the project was to develop a magnetic coupling that would expand the working temperature space to succeed in temperatures of molten salts around 600°C. By exchanging the internal drive with a magnetic materials containing the next Curie level and boosting the magnetic area of the outer drive with special magnetic designs; it was possible to develop a magnetic coupling that began at a decrease torque degree at room temperature, however only had a minor discount in torque stage as a function of temperature. This resulted in superior performance above 160°C, regardless of if the benchmark was against a Neodymium- or Samarium Cobalt-based system. This could be seen in Figure 1, where it is proven that the torque level of the High Hot drives has been examined up to 590°C on the internal drive and nonetheless performed with an almost linear discount in torque.
The graph additionally reveals that the temperature coefficient of the High Hot coupling is even decrease than for the SmCo-system, which opens a decrease temperature market the place efficiency stability is important over a bigger temperature interval.
Conclusion At Sintex, the R&D department remains to be developing on the know-how, but they need to be challenged on torque degree at both totally different temperature, dimensions of the magnetic coupling or new applications that have not previously been potential with normal magnetic couplings, in order to harvest the total potential of the High Hot expertise.
The High Hot coupling just isn’t seen as a standardized shelf product, but as an alternative as custom-built by which is optimized for particular applications. Therefore, additional growth shall be made in shut collaboration with new partners.

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