Review temperature together with the magnetic operating point.
Grade Suffix = Selection Reference
NdFeB grades carry a temperature suffix: standard N grades to ~80°C, M to 100°C, H to 120°C, SH to 150°C, UH to 180°C, EH to 200°C, TH to 220°C. These are conventional grade references, not guaranteed part limits. Irreversible loss can occur below them if the magnetic circuit or opposing field is unfavorable.
Demagnetization Depends on Load Line
Thin magnets or magnetic circuits with a low permeance coefficient can have less demagnetization margin. Review the load line and demagnetization curve at the actual magnet temperature.
Define the Required Temperature Margin
Agree the design margin using the actual magnetic circuit, demagnetization curves, continuous and peak temperatures, and opposing fields. A fixed percentage or temperature offset is not a universal selection rule; validate the operating point with engineering before release.
Verify the Operating Point
Review the magnetic circuit and temperature together rather than selecting a grade from a temperature number alone.
NdFeB requires protection; other materials often don't. Match the coating to the environment:
Coating
Thickness
Best For
Ni-Cu-Ni
15–20 µm
General purpose, 48–72h salt spray
Epoxy
15–25 µm
Outdoor, marine — 240h+ salt spray
Zinc
8–12 µm
Cost-sensitive, dry environments
Parylene-C
5–20 µm
Medical, thin and pinhole-free
Phosphate
~2 µm
Vacuum, clean, short-term storage
SmCo, ferrite, and AlNiCo generally need no coating.
Step 5
Tolerances: Ask Only for What You Need
Sintering affects final dimensions. Define the functional faces and required tolerances so machining or grinding can be planned where needed:
✓Standard ground tolerance — ±0.05 mm on ground faces, ±0.1 mm on as-sintered faces. Confirm the required tolerance against the part geometry and process
✓Precision grinding — ±0.02 mm or better is available for sensor and instrument magnets
✓Put tolerances on functional faces only — leave non-critical faces at standard tolerance and cut cost
✓Bonded magnets — ±0.05–0.1 mm as-pressed with no grinding, ideal for complex shapes
Step 6
Design for Magnetization and Assembly
The magnet is part of a system — design the system.
Magnetization & Field
Define the field and magnetization direction.
Finished Geometry
Specify the finished geometry before manufacture.
Shipping Condition
Agree supply condition and shipment protection.
Surface & Interface
Protect surfaces and inspect contact features.
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Magnetization Patterns
Define magnetization direction, pole pattern and accuracy in the drawing. Material orientation and magnetizing-fixture requirements constrain the available patterns; agree the magnetization and assembly sequence before production.
Plan Specialist Magnet Machining
Sintered NdFeB and SmCo are brittle; mounting features require a manufacturability review. Grinding or specialist cutting may be needed. Threads and press-fit interfaces are usually provided by a housing or backplate; bonded-material machining depends on the formulation.
Charged vs Uncharged Shipping
Charged magnets simplify your line but complicate transport (IATA rules). We ship either way, with proper packaging and documentation. Tell us your assembly process and we recommend the best option.
Protect Finished Surfaces
Define contact points, separation and packaging for the intended coating and assembly sequence.
✓Specifying Br when you need force — remanence is a material property; force depends on the whole magnetic circuit. Share the application and we engineer backward from the force you need
✓Thinner and thinner magnets — thin sections demagnetize easily and are fragile to handle. Below 0.5 mm, consider bonded or flexible materials
✓Ignoring the steel return path — magnet performance changes completely with and without a back-iron. Include it in the simulation
✓Chamfers skipped — unchamfered edges chip during handling and assembly. A 0.1–0.3 mm chamfer is a design reference; confirm its effect on the magnetic volume, mating fit and edge acceptance
✓Over-specifying tolerance everywhere — precision on non-functional faces adds grinding and inspection cost; ask for a cost comparison before tightening a tolerance
✓No temperature test data — agree flux verification at the limiting operating conditions; the published 120°C reference is not a universal validation threshold
Let Us Review Your Design — Free
Send your drawing or concept. Our engineers check the magnetic circuit, temperature margin, and manufacturability, then recommend the most cost-effective spec.
SELECTION GUIDEMagnetization, assembly and handling guidanceExplore applications and requirements