Permanent Magnet Simulations

By: Michael Brand, President, SM Magnetics

Today’s permanent magnet FEA and simulation modeling software is tremendous. They can help answer critical questions about motor performance, holding forces, flux density, sensor selection, and a host of other application requirements before any prototypes need to be made.

There are many considerations that go into any design, so when using simulations as your initial guide remember to consider several permanent magnet variables that could have a direct effect on performance of the magnet or magnetic assembly. Below are some variables to consider.

Thickness of Coating or Plating

While the coating thickness on a magnet or magnetic component may seem too thin to have an effect on the performance, it will cause an airgap that needs to be considered in some applications. Understand the coating being used on every component and the thickness of each.

Type and Thickness of Steel

Steel plays a critical role in the magnetic circuit on the magnet field. Know the material specs of the steel so the simulations can be as accurate as possible. Understanding the Bsat of each steel will be important.

Temperature

The magnetic strength can change due to elevated temperature if the incorrect magnetic material is not selected. Simulating the effects of the temperature on the magnet or magnet assembly will be dependent upon many variables, including shape, size, surrounding metals, etc.

Material Grade

Published material specs should be used as a reference only. The published material information gives B and H specs in a closed-circuit test, however the shape, thickness, load line, and manufacturing processes can make the B and H perform differently than anticipated.
Magnet or Magnetic Exposure Outside of the Application

It is important to understand the entirety of the application, and the environment it will be exposed to in the final product. What’s happening with the magnet or magnetic assembly once in operation? Ultrasonic cleaning? Thermal cycling? Understand the environmental

and use factors that the final product will be exposed and take them into consideration during simulations.

Make a Prototype and Confirm the Simulation

Validate the simulations with a prototype. After the prototype is built run the simulations again to match the results of the prototype. This will provide a road map for the next prototype.

 

Summary

Simulations are an excellent resource but must include consideration of all design and environmental factors to be accurate. Consulting a magnet professional may be the starting point to shorten the time from concept to production.

 

About SM Magnetics: SM Magnetics is privately owned company, providing assistance with magnets, magnetic circuit design, engineering support, and production. For more information, logon to our website, www.smmagnetics.com , or contact us at 205-621-8841.


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