Maximum Operating Temperature vs. Curie Temperature: Understanding the Limits of Magnets

What Happens When Magnets Get Hot?

Magnets are strong. But heat can make them weak. There are two big heat numbers to know:

• Max Operating Temperature (We call it Tmax)
• Curie Temperature (We call it Tc)

It’s like this: If you put a magnet in a hot oven, it will get weak. If you make it too hot, it won’t be a magnet anymore!

This can be vary dangerous depending one where the permanent magnet is used. If the magentic force is decreased, it is possible that car and plane crashes can happen.

What are the Two Big Heat Numbers?

Curie Temperature (Tc)

This is the BIG one. If a magnet gets this hot, it’s not a magnet anymore. Poof! The magnet power is gone. It can’t come back. For NdFeB magnets, this is around 310-400°C. That’s hotter than your oven at home!

Maximum Operating Temperature (Tmax)

This is a smaller number. It’s the safe heat for a magnet. If you go over this, the magnet gets a little weak. It might not work right. This is usually about 50-80% of the Curie Temperature.

Example: If the Curie Temp is 300°C, the Max Operating Temp might be 150°C. It is much smaller.

• NdFeB magnets have a lower Tmax than some other magnets.
• For Applications under 200 Degrees Celsius, use NdFeB. It is cheap and strong.

Why Do These Numbers Matter?

If a magnet gets too hot in a machine, bad things happen!

• Motors can stop working.
• Sensors can give the wrong numbers.
• Generators can lose power.

Example: In electric cars, if the magnets get too hot, the car can’t go as fast! 30% of magnet problems in factories are from too much heat! We do not want that! You do need to worry about this. If, for instance, your magnet is in an Electric Vehicle, it is important to use the right one. If you go over the Tmax, your car’s motor may not work. You can be in big trouble if that happens.

Do you Need magnets that can get hot? See our good NdFeB Magnet Grade options!

Different Magnets, Different Heat Limits

We make NdFeB magnets. They are the strongest, but they can’t get as hot as some others.

We can add a special coating to our magnets. This helps them stay strong, even when it’s hot! It also makes the magnet resist corosion. We are good at making Customized NdFeB Magnets.

What Heat Does to NdFeB Magnets

When NdFeB magnets get hot, they can change inside. This makes them weaker. Even if they don’t get to the Curie Temperature, they can lose some power. We should prevent this.

Pro Tip: If you need a magnet to work at more than 150°C, use special NdFeB types! Ask us about UH (Ultra-High) or SH (Super Heat-Resistant) magnets! These are very good.

We have special NdFeB magnets for very hot places!

• 38SH
• 42EH

We check our magnets to make sure they are good. We do not what to use poor quality magnets! We follow the rules (ISO 9001/TS16949).

How to Pick the Right Magnet

1. What’s the hottest your magnet will get? Think about everything that makes heat.
2. Will it get hot and cold fast? Will it get hit? Will it be near things that rust?
3. Ask us! We can help you pick the best magnet.

Need help? Our smart workers can look at your project for free!

How to Keep Magnets Safe From Heat

• Use things that take heat away (like fans).
• Make sure air can move around the magnet.
• Don’t use a magnet that’s too close to its heat limit.

We make NdFeB magnets that are very good at staying strong in the heat. We tell you the exact Tmax.

 Questions You Might Have