Rare Earth Magnets


Rare earth magnets increased the strength of magnets by nearly 300 percent compared with old-style iron magnets. This made a big difference in servo motors, as you may already know — but what exactly are rare earth magnets?

One thing they’re not: rare. Neodymium magnets and samarium-cobalt magnets are made of materials that are just about as rare as tin.

There are 33 elements known as rare earth, in two series, lanthanide and actinide. Neodymium and samarium are both in the lanthanide series. Uranium is one of the better-known members of the actinide series.

Rare earth elements are potentially magnetic just as iron is, but they normally have this property only when they’re very cold. In the second half of the 20th century, researchers discovered that the rare earth materials could be alloyed with metals like iron and cobalt. Once these alloys are formed, you’ve got super strong magnets at room temperature.

Initially, these super magnets were used for special purposes and you were most likely to find them in an AC servo motor or a hard drive.

Now, while they power electric cars and such, you can also find them on refrigerator doors like all other magnets. It’s easy to think of them simply as a newer, better magnet.

Think again. They’re fine as long as they’re in your servo motor. Get a couple of these babies out and play with them, though, and you will discover that they are not the same as iron magnets.

For example, if you have two of these magnets near one another and incautiously get a part of your body in between them (yes, it happens), they can break bones in their eagerness to get nearer to each other. There have actually been cases of death involving two rare earth magnets and a body part.

And yes, the people involved in those accidents were absolutely doing things their moms told them not to do.

Resist the temptation. Rare earth magnets are impressive, but they’re better off inside your servo motors doing their jobs.

If you need support for your Indramat or Indradrive servos, give us a call. We’re in our element working with your legacy or new motion control.

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