magnetic couplings
Magnetic couplings enable torque transmission without the need of a physical contact of their individual parts. They work on a similar principle as electric motors with permanent magnets. The coupling consists of two „cylinders“ with bonded magnets forming a multi-pole structure – an internal cylinder with magnets bonded to the external diameter, a larger cylinder with magnets bonded to the internal diameter, with both cylinders inserted in each other. An external part is usually connected to a drive unit. The poles on one cylinder are positioned against opposite-magnetised poles of the other cylinder (North – South) and generate a strong magnetic field, thanks to which both cylinders rotate synchronously. When overload occurs, the poles of both parts of the coupling slip and the load is therefore protected from too much torque.
areas of use
manufacturing of magnetic couplings in PZK BRNO
We manufacture synchronous magnetic couplings with permanent magnets. We focus on special applications having a high demand for the design quality. In our own testing laboratory, we test magnetic properties of individual magnets as well as the resulting assemblies and the strength of bonded joints. We check dimensions on our own coordinate measuring machine (CMM) and perform balancing on our own balancing machine. Using the finite element method (FEM), we are able to design or optimise a suitable solution.
we specialise in
- torque calculation for magnetic couplings
- design of magnetic couplings
- prototyping
- batch production of magnetic couplings
use of magnetic couplings
Magnetic couplings can be found in pumps, compressors, dispensers, and other applications. Where the extremely toxic substances or other aggressive media are used, individual parts of the equipment should be hermetically sealed. Magnetic couplings act as a „barrier“ and their capability of pole „slipping“ in case of overload minimises the risk of damage to the pump and the connected equipment. Further advantages of magnetic couplings are that they do not require maintenance, they help reduce vibrations, they partially compensate misalignment of shafts of individual parts, and they limit the maximum torque of parts.
design of magnetic couplings
In addition to their „cylindrical“ design, synchronous magnetic couplings are also manufactured as „discs“, which can be used where a sufficient space is not available for a cylindrical coupling. They consist of two flat parts with magnets bonded to the inner sides positioned against each other. Disc magnetic couplings offer all the advantages of „cylindrical“ magnetic couplings, but typically transmit less torque.
magnet types in couplings
Neodymium as well as samarium permanent magnets are used in magnetic couplings. The application determines which of them is to be used. The neodymium-based permanent magnets have a higher magnetic flux, thus they transmit a higher torque but their use is limited by the thermal class of the magnet. These magnets can be used for temperatures approximately up to 230°C and they are sensitive to corrosion. Samarium magnets are used where neodymium magnets meet their limits. Samarium-based magnets have a high temperature resistance up to 350°C and an excellent corrosion resistance.
Jan Kratochvil ml.
