The magnetic coupling consists of two parts: the drive and the follower.
The drive is part of the mechanism that is connected to the prime mover (motor). By magnetic interaction, the follower reacts to the motion of the actuator, resulting in the non-contact transmission of mechanical energy. This non-contact power transmission has several advantages:
• Component isolation, which minimizes or eliminates mechanical vibration through magnetic damping and allows a mechanical barrier to be inserted between the drive and the follower to separate the environment and allow operation under differential pressure.
• High tolerance between axial, radial and angular misalignment between the prime mover and the load.
• Allow speed changes and adjustments between the prime mover and the load.
In order to obtain the optimal air gap magnetic field strength for magnetic circuits of the same type and size, you should choose the most suitable magnetic material for coupling. The torque transmitted by the permanent magnet material must include the following characteristics:
1. High residual flux density for strong magnetic and magnetic moments.
2. High coercivity (Br) to avoid degaussing at high operating temperatures; that is: magnets require high magnetic energy products (BHmax)
3. Excellent temperature stability, the material has the ability to maintain magnetic stability.
A permanent magnet is a hard magnetic body having a high coercive force and a high remanence and can maintain a constant magnetic force for a long period of time once magnetized. It can be divided into two types:
1. Metal alloy magnets: Nd2Fe14B, SmCo and AlNiCo
NdFeB - Temperatures up to 150 °C. Need to prevent corrosion.
SmCo - Temperatures up to 350 °C. Anti-corrosion optional.
Ceramic - Temperatures up to 250 ° C. No corrosion protection is required.
Hastelloy (hysteresis coupling) - Temperatures up to 350 °C. No corrosion protection is required.
All of the above permanent magnets can be used for magnetic coupling. However, due to the high magnetic energy product (BHmax) and intrinsic coercivity, NdFeB is the most widely used magnetic material. At high operating temperatures (above 200 degrees Celsius), SmCo magnets can be used that can reach 250 to 300 degrees Celsius.