HANGZHOU TENGYE MAGNETIC MATERIALS CO., LTD.

Expert Magnetic Coupling Manufacturer | for pump industry only

inner rotor and out rotor

What is a magnetic coupling?​

A coupling is a device used to connect two shafts for the purpose of power transmission. A traditional coupling transmits power from one shaft to the other by means of physical contact, while a magnetic coupling in a contact-free manner.

A permanent magnetic coupling consists of two coaxial rotary elements, i.e. the driving element and the driven element with a radial air gap. Two elements are called inner rotor and outer rotor. Besides, there is a canister (containment shroud) between two rotors functioning as a static seal. Basically, a mag coupling works on the principle that opposite poles attract. By forming a closed flux loop, the inner rotor and the outer rotor are magnetically coupled.

magnetic coupling for pump

Who developed the first magnetic coupling?​

Mag coupling was first applied in magnetic drive pumps. And the first magnetic drive pump was developed by HMD Kontro (a UK company), which was later acquired by Sundyne. 

HMD Kontro is recognized as the pioneer of sealless pump engineering and manufacturing. At that time, the development of this magnetic drive pump was a breakthrough in the industry. The risk of emission or leakage is greatly reduced with a magnetic drive sealless pump.

Permanent Magnets in a magnetic Coupling

Which type of magnets are used?

In the early days, ceramic magnets were used in magnetic couplings. Because of its low maximum energy product, a magnetic coupling made of ceramic magnets produce much smaller torque than a traditional coupling of the same size. Ceramic magnets almost inhibited the development of mag couplings.

However, with the development of rare earth magnets (SmCo and NdFeB), magnetic couplings were able to produce larger torque. The size were getting smaller while the torque stronger. Nowadays, Sm2Co17 and sintered NdFeB are most widely used magnets. 

In the early days, ceramic magnets were used. Because of its low maximum energy product, a magnetic coupling made of ceramic magnets produce much smaller torque than a traditional coupling of the same size. Ceramic magnets almost inhibited the development of magnetic couplings.

However, with the development of rare earth magnets (SmCo and NdFeB), magnetic couplings were able to produce larger torque. The size were getting smaller while the torque stronger. Nowadays, Sm2Co17 and sintered NdFeB are most widely used magnets in mag couplings. 

SmCo or NdFeB? How to choose the magnets and grades?

Depending on the specific working condition, Tengye designs and prototypes custom mag coupling for customers. One of the critical considerations in designing a magnetic coupling is the selection of permanent magnets. Generally, the following technical information will be collected from the customer:

  • maximum torque requirement
  • maximum working temperature
  • installation space
  • RPM of the electric motor

With our extensive and in-depth knowledge in magnetics, we will find out the most suitable magnets for you.

About Tengye: Tengye supplies finest permanent magnetic materials and assemblies to world industry. We work closely with our customer from designing stage to mass production. 

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