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# Torque Calculation for Magnetic Coupling

## Torque Calculation for Magnetic Coupling

(OP)
Has anyone found any torque calculations for magnetic coupling; i.e. what magnetic strength is required to support the torque from the motor shaft? I have done a bunch of online research and it seems the only way to calculate this number is by running simulations; which is hard to believe because there are a lot of companies that manufacturer mag drive pumps and I can't believe that they run simulations every time they design a new pump. There has to be some sort of standard or rough calculation. thread340-374735: Torque Calculation for Magnetic Coupling

### RE: Torque Calculation for Magnetic Coupling

Many times, the torque can be calculated by 2D freeware/shareware programs such as FEMM. After you get over the initial learning curve, it isn't difficult and solving time is minimal.

Sometimes an existing design can be lengthened/shortened to a desired torque since it'll scale linearly.

There are a number of analytical expressions published in IEEE Transactions on Magnetics by Furlani. With a moderate amount of programming ability, one can write a program that'll take the relevant parameters and calculate the torque directly.

Do you have a particular application or specific set of dimensions in mind? You'll find a number of people in this forum are happy to run a feasibility analysis in their software.

### RE: Torque Calculation for Magnetic Coupling

https://hal.archives-ouvertes.fr/hal-00673920/docu...
"Simple Analytical Expressions for the Force and Torque of Axial Magnetic Couplings" by Thierry Lubin, Mezani Smail, Abderrezak Rezzoug
It didn't look simple from a quick skim, but I guess it's all relative

=====================================
(2B)+(2B)' ?

### RE: Torque Calculation for Magnetic Coupling

The most relevant Furlani paper would be the following (there is a cost for non-IEEE members):

E. P. Furlani, R. Wang, H. Kusnadi, “A Three-Dimensional Model for Computing the Torque of Radial Couplings”, IEEE Transactions on Magnetics 31, 2522-2526 (1995)

### RE: Torque Calculation for Magnetic Coupling

(OP)
MagMike the application is a small mixer, I already have the design in solidworks. Electripete thank you for the link, I have that paper I just have not had the chance to read it. My design is a little different I don't have the adjacent plates, I have the design that they use mostly for pumps when you have a magnetic cup drive magnet and a following magnet that sit inside of it; see the attached photo. MagMike I will try to get a hold of that paper thank you for all the help. If I have more questions I will be sure to ask.

### RE: Torque Calculation for Magnetic Coupling

Mike,2D assumes inifinite 3nd dimention. As for torque, the 3nd dimention, i.e. the length of magnet, is one of key parameters to determine the torque. Did you find the torque was overated when using 2D simulation? since the force is propotional to the "contacting" area, presumably the torque is proptional to the length of your magnets ( not the depth).

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