By Temperature Resistance
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List of products
1Measure the real temperature, not the ambient one
The temperature that matters is the one at the magnet under continuous load, not the temperature of the room. Inside a motor, a light fitting, an engine bay or a machine housing it is routinely far higher than anyone expects.
If you cannot measure it, estimate on the high side. Choosing one grade too low is a permanent, irreversible loss; choosing one grade too high only costs a little more.
2Read the grade letters
The letter after the grade number states the temperature class: N up to about 80 °C, M to 100 °C, H to 120 °C, SH to 150 °C, UH to 180 °C and EH to 200 °C. The exact maximum working temperature is listed in the parameters of every product.
The trade-off is that the higher temperature classes generally deliver a slightly lower pull force for the same size, which is worth accounting for when you compare.
3Use the bands as a shortlist
- 41 to 80 °C: interiors, household, office, workshop. This covers most of the range.
- 81 to 120 °C: warmer plant rooms, light fittings, machine enclosures.
- 121 to 150 °C: motors, drives and industrial equipment.
- 151 to 200 °C: thermally demanding assemblies and rotating machinery.
- Above 200 °C: a specialist case where samarium magnets are usually the better answer.
4Understand what overheating actually does
Below the maximum working temperature, a magnet loses a little force while it is hot and recovers it when it cools. Above that limit the loss is permanent: the magnet never regains its original force, even at room temperature.
Overheating also happens accidentally during assembly. Drilling, grinding and welding near a mounted magnet can push it past its limit in seconds, so fit the magnet after the hot work, not before.
5Check the coating as well as the grade
Temperature and environment go together. A magnet rated for 150 °C but plated with standard nickel is still a dry-interior product; heat combined with humidity or chemicals attacks the coating and the corrosion follows. For hot and damp conditions, discuss the coating with us rather than choosing on temperature alone.
Tip: For anything permanently above 200 °C, look at samarium magnets instead. They hold less force per millimetre than neodymium, but they keep working where every neodymium grade has already given up.
Related categories to the Selection by temperature resistance category
- Temperature resistance 41 to 80 °C
- Temperature resistance 81 to 120 °C
- Temperature resistance 121 to 150 °C
- Temperature resistance 151 to 200 °C
- Temperature resistance 201 to 350 °C
- Block magnets by temperature
- Cylinder magnets by temperature
- Segments by temperature
- Atypical magnets by temperature
- Ferrite magnets by temperature
- Heat-resistant magnets
- Samarium magnets
- Selection by pull force
- All neodymium magnets
Frequently asked questions about temperature resistance
They are the temperature classes of the material. N works up to roughly 80 °C, M to 100 °C, H to 120 °C, SH to 150 °C, UH to 180 °C and EH to 200 °C. The letter appears after the grade in the product name, and the exact maximum working temperature is listed in the parameters of each product.
The loss becomes permanent. Below the limit a magnet gives up a little force while it is hot and recovers it on cooling. Above the limit it never regains its original force, even back at room temperature. This is why a grade chosen one step too low shows up as a motor or a fixture that has quietly weakened after a few weeks of operation.
Generally yes. For the same size, the higher temperature classes deliver a somewhat lower pull force than a standard N grade, because the material is formulated for thermal stability rather than maximum energy product. Compare the stated pull force of the specific product rather than assuming the size tells you the force.
Samarium magnets. Every neodymium grade has reached its limit by around 200 °C, whereas samarium keeps working well beyond it and also resists corrosion better. It holds less force per millimetre than neodymium, so expect a slightly larger part for the same job.
Easily. Drilling, grinding or welding near a mounted magnet can push it past its temperature limit within seconds, and the resulting loss is permanent. Carry out all hot work first and fit the magnet afterwards. Mechanical shock during assembly is the second common cause of damage, since the material is brittle and chips at the edges.
Temperature is the parameter that most often decides whether a magnet survives its application, so we state the maximum working temperature for every product and let you filter the neodymium range in five bands from 41 °C up to 350 °C. We also explain what the grade letters N, M, H, SH, UH and EH mean and where the limit of neodymium lies, because above roughly 200 °C samarium magnets are the better answer. Tell us the real temperature in your assembly and we will point you to the right grade.
