Magnetic Couplings are used in the industry to transmit torque through a gap. This gap is the distance between two members of the coupling. Between this gap, one may have air, vacuum, fluids, separator cups, or other similar items.
There are two basic configurations that are utilized; the Axial and Radial designs. The Axial design requires that the two magnet systems face each other, similar to two pancakes facing each other. As one member rotates, the other follows. The maximum torque will be determined by many factors, such as air gap, number of poles, materials selected, working temperature, etc.
The Radial design requires that the magnet systems are concentric to each other. As one member (typically the outer) rotates, the other follows.
When selecting the barrier material between the coupling members, consider eddy current effects, since the flux lines of the magnetic coupling will cut the barrier material. Conductive materials will start to heat as the RPM is increased. Conductive materials used as the barrier material will lead to resistance of the coupling motion, as some of the input work will turn into the eddy current losses (heat). At higher RPM, over 600 RPM, this loss can be significant.
Typically, coupling assemblies do not exist as a standard "off the shelf" item. They have to be designed for each application, then manufactured. Depending on the complexity of your design, engineering charges may apply. If you are able to use a configuration that is close to something that we already have designed, and you are not concerned about "optimizing" the configuration, engineering/design charges will not apply.
Couplings may be hermetically sealed so that they may work in harsh environments, such as chemical applications. Applications of magnetic couplings include nuclear environments, chemically hazardous environments, high temperature environments, oil drilling applications (downhole), vacuum applications, and vibration isolation applications.
Industries that have benefited from magnetic couplings include aerospace, medical, chemical, pharmaceutical, food, biotechnology, industrial ovens, compressors, metering, and hydraulics, because magnetic couplings are the only device that can transmit contact free torque.