High Temperature NdFeB Magnets, H to EH Grades

Temperature picks the grade, not flux

This is the one page where the grade table, not the geometry, is the product. Sintered NdFeB loses flux as it heats and recovers it on cooling — until it passes its maximum operating temperature, after which the loss becomes permanent and the magnet is scrap. The maximum operating temperature by grade series is: N up to 80 °C, M up to 100 °C, H up to 120 °C, SH up to 150 °C, UH up to 180 °C, EH up to 200 °C. Tell us the temperature your part will actually reach and we start from the lowest series that clears it, because a hotter grade costs flux.

N52 is the grade most often misused

N52 has the highest flux of the sintered grades and the lowest heat tolerance: its maximum operating temperature is 60 °C, against 80 °C for N35–N48. A designer who picks N52 to maximise force on a part that will run at 90 °C will get a magnet that is strong on the bench and demagnetized in service. For higher temperatures we move to an H, SH or UH grade and accept slightly lower flux — the correct trade is a smaller, known number instead of a larger number that does not survive.

What H / SH / UH / EH are each for

The series differ by intrinsic coercivity, which is what resists demagnetization at temperature: M for mildly warm assemblies, H for a part near a warm housing, SH for motor and automotive work that sees sustained heat, UH for harsher automotive and industrial duty, and EH where the environment approaches the practical limit for NdFeB. All are produced across N35–N52 where the grade and coercivity combination exists.

Coating matters more at temperature

At temperature, coating adhesion matters more than at room temperature, and the usual Ni-Cu-Ni finish is joined by black epoxy and phosphating where the part sees humidity as well as heat. Salt-spray duration is quoted per coating within a 12–96 hour window — tell us the hours and the environment and we match the coating rather than defaulting.

Inspection

Each batch is verified on a flux meter, with coating thickness and adhesion, salt-spray or humidity, pull-force and dimensional checks, plus a 100 % final inspection before packing. For temperature-critical parts we confirm the grade against the drawing before pressing, not after.

Lead time and samples

Samples 10–15 days, small batches 20–30 days, mass production 40–60 days. In-stock samples are free — freight only. Send the maximum temperature the part will reach in service, plus the drawing; we return the recommended series, its flux penalty and a quotation within one business day.

Available magnetisation directions — Block / bar magnets

The magnetisation direction is fixed when the magnet is magnetised and cannot be changed afterwards, so the direction must be confirmed before production.

• Magnetized Through ThicknessPoles are on the two largest faces; the field runs through the thin dimension.
• Magnetized Through The WidthPoles are on the two long narrow faces; the field runs across the width.
• Magnetized Through The LengthPoles are on the two short ends; the field runs along the length.

Manufacturing capability & measured data

Related Products

• Custom Curved Arc Ndfeb Material U Shape Magnet

Product catalog

• Products
• Magnet Calculator
• Contact
• Custom Shape Magnets

Same-category magnets

• Arc Magnet N35 N52 Strong Motor Materials
• N52 Custom Round Industrial Nickel Coated Ndfeb
• N35 N48 N52 Ndfeb Magnets Custom Photo Display
• N35 N40SH Neodymium Magnets N52 Ring Square Block