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NdFeB Grade Chart: N35–N52 and Temperature Suffixes
A procurement reference for reading the number, coercivity suffix and indicative temperature category before preparing an RFQ.
Reference note: Market prices and capacity figures are volatile reference points, not quotations or guarantees of current availability.
| Designation | What it indicates | Example maximum use temperature |
|---|---|---|
| N35–N50 without suffix | Standard coercivity category across energy-product families | Typically 80°C in the cited table |
| N52 without suffix | High energy-product standard category | 60°C in the cited table |
| M | Higher intrinsic coercivity than standard | 100°C |
| H | Higher coercivity category | 120°C |
| SH | Still-higher coercivity category | 150°C |
| UH | Ultra-high coercivity category | 180°C |
| EH | Extremely high coercivity category | 200°C |
Orientative only. Exact available combinations, properties and temperature limits vary by manufacturer, grade, geometry and magnetic circuit.
How to use this chart
This chart is an RFQ orientation tool, not an engineering approval table. It shows how a common NdFeB designation combines an energy-product number with an optional coercivity suffix. Use it to ask the right supplier questions, then confirm the exact grade data, demagnetization curve and maximum-use guidance for the offered material and part geometry.
Manufacturer ranges differ. Even within one published catalogue, not every number is available with every suffix. The temperature shown for a category can change with composition, magnet dimensions and the operating point in the magnetic circuit. A controlled specification should reference approved properties, not simply copy the highest temperature associated with a suffix.
Reading N35 through N52
The number following N identifies a maximum-energy-product family, commonly expressed in MGOe. N35, N38, N40, N42, N45, N48, N50 and N52 move through progressively higher energy-product families. The number helps describe room-temperature magnetic output but does not state intrinsic coercivity, coating, corrosion resistance, magnetization direction or dimensional capability.
Higher energy product can support more field from a given material volume, but “higher” is not automatically “better.” Increasing energy density may come with a different coercivity or temperature tradeoff. The application still defines the required flux, air gap, working point, demagnetizing field, temperature and allowable size. Procurement should preserve the approved number and request deviations explicitly.
The standard no-suffix category
In Arnold Magnetic Technologies’ published table, standard N35 through N50 grades carry an example maximum use temperature of 80°C, while N52 is listed at 60°C. That difference illustrates why the energy-product number alone cannot be used as a temperature ranking. The highest listed number does not automatically carry the highest usable temperature.
These values belong to that manufacturer’s grade data and should be treated as reference points. A thin magnet working against a strong opposing field can have a different demagnetization margin from a larger magnet of the same material. Ask for the offered grade’s temperature curves and have the responsible engineer review the real magnetic circuit.
M and H suffixes
M and H mark higher intrinsic-coercivity categories than a standard no-suffix grade. In the cited Arnold table, M grades are associated with an example maximum use temperature of 100°C and H grades with 120°C. Available energy-product numbers narrow or change as the coercivity category rises, so an exact designation must be confirmed with the source.
A drawing should not use M or H as a substitute for application context. State normal and exceptional temperature, duty cycle, nearby heat sources and the consequence of irreversible demagnetization. If a supplier offers a different suffix, request the magnetic-property difference and composition statement instead of accepting “high temperature” as a complete technical answer.
SH, UH and EH suffixes
SH, UH and EH continue into higher coercivity categories. The cited grade table uses example maximum temperatures of 150°C for SH, 180°C for UH and 200°C for EH. These labels communicate resistance to demagnetization at demanding temperatures; they do not mean that every assembled component can operate continuously at the catalogue number.
Adhesives, coatings, adjacent plastics, mechanical retention and the thermal path can impose lower limits than the magnet material. An assembly RFQ should therefore quote the complete component and identify which requirement controls temperature. Ask the potential manufacturer to state the exact magnet grade and every other material that limits the offered assembly.
Composition and export exposure
Higher-coercivity NdFeB grades may use dysprosium or terbium, including through grain-boundary diffusion. China’s non-automatic export controls apply to NdFeB magnets containing either element and to all SmCo magnets. NdFeB made only with light rare earths remains outside that specific rule. The actual composition, not the suffix alone, determines exposure.
The suffix should therefore trigger two parallel requests: engineering data for the temperature and demagnetization requirement, and a supplier composition statement for sourcing. In the verified N42SH case, dysprosium is present and licensing applies. Do not generalize that single composition statement to every manufacturer’s entire suffix range without current documentation.
Grade availability is part of the quote
A catalogue can show that a grade family exists without proving that it is available for the requested geometry, coating, tolerance, quantity or origin. Ask each potential source to repeat the exact offered designation, identify manufacturing location and list any deviation. Treat a shortened designation or an “equivalent” grade as an open technical question.
Prototype and recurring production may also use different process assumptions. Record sample quantity, initial order and annual volume separately. Ask whether the prototype material and tooling match the proposed production route, and whether later changes require notification. The goal is a grade comparison tied to the actual component, not a catalogue-only screening exercise.
What belongs on the drawing and RFQ
Use the approved grade designation, required magnetic properties, magnetization direction, geometry, coating, tolerance basis and operating conditions. If the grade is not yet approved, say so and provide the application data needed for a proposal. Mark the proposal as a deviation requiring review rather than allowing the source to choose an invisible substitute.
For controlled compositions, request manufacturing origin, composition evidence and a separate export-licence assumption. For all grades, separate tooling, production, inspection and freight timing. This creates a record that engineering can evaluate and procurement can price without mixing material performance, country of origin and delivery risk into one undefined grade code.
The chart’s useful limit
The chart is most useful when it stops a premature comparison. N42 and N42SH share an energy-product number but not the same coercivity category or sourcing exposure. N52 has a higher number but a lower example maximum-use temperature than many suffixed grades in the cited table. Those contrasts show which questions the designation leaves unanswered.
Use the number and suffix to route the RFQ, then replace orientation values with the offered manufacturer’s data and the buyer’s approved requirements. Record the source and review date of every table used. That discipline keeps a convenient reference from becoming an unsupported specification and makes later supplier or grade changes easier to audit.
Questions buyers ask
Does a higher NdFeB number always mean a better magnet?+
No. The number identifies an energy-product family; coercivity, temperature, geometry and the magnetic circuit determine suitability.
Is 150°C a universal limit for every SH magnet?+
No. It is an example from a cited manufacturer table. The supplier’s data and the application operating point control the decision.
Do all high-temperature suffixes contain dysprosium or terbium?+
The suffix should trigger a composition request, not replace one. Export exposure depends on the actual supplier composition.
Technical references
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