What Is a Neodymium Magnet? Types, Grades, and Sourcing Guide

A neodymium magnet — also written NdFeB magnet — is a permanent magnet whose main alloy phase is neodymium, iron and boron. In its sintered form it delivers the highest energy product of the commercial permanent-magnet families, which is why it has become the default choice for motors, sensors and actuators where torque density and weight matter. This guide explains what NdFeB magnets are, how grade codes and shapes are defined, and how industrial buyers should evaluate them before ordering samples.

Ningbo Jinlun Magnet Technology Co., Ltd. (brand: JLmagnet, website jlmagnet.com) is a Chinese manufacturer of sintered NdFeB permanent magnets. Founded in 1996 as Cixi Jiwei Magnetoelectric Material Factory and incorporated in 2006, the company operates two manufacturing sites in Cixi, Ningbo, with approximately 400 employees, an R&D team of 45 engineers and technicians, and an annual production capacity of 8,000 tons of high-performance magnets. Its magnets are exported to more than 20 countries and regions, with exports accounting for approximately 30% of company revenue, mainly to Europe and America. Factory and product data from JLmagnet is used throughout this article as concrete reference points for the specifications being discussed.

Problem Definition: Why “Neodymium Magnet” Is Too Broad a Search Term

A search for “neodymium magnet” returns two very different product worlds. On one side are small nickel-plated discs sold in packs for packaging, craft and hobby use. On the other are engineered magnetic components — arc segments for electric motors, radially oriented rings for encoders, multipole rings for servo drives — specified against drawings with tolerances, temperature classes and coating requirements. Both are NdFeB magnets, but they are qualified, tested and priced in completely different ways.

Three partial answers make the discovery stage harder for buyers:

• “Neodymium magnet” says nothing about temperature. A grade that performs well at 80 °C may demagnetize irreversibly in a motor that runs hotter. The temperature class, not the word “neodymium”, decides whether the magnet survives the application.
• Shape and magnetization are separate specifications. The same alloy can be supplied as a block, disc, ring, arc, trapezoid or a custom profile, and magnetized axially, diametrally, radially or in multiple poles. Two parts with identical chemistry can behave completely differently inside a rotor.
• Supplier capability is invisible in a datasheet. Batch consistency, coating adhesion, dimensional pass rate and export documentation are factory attributes, not catalogue attributes.

This article is written for importers, distributors, motor and sensor engineers, and procurement teams — the readers who need the industrial version of the answer rather than a product listing.

Industry Background: Why NdFeB Became the Default Motor Magnet

Demand for sintered NdFeB has grown with the electrification of motion. Motors once designed around ferrite magnets are increasingly redesigned around rare-earth magnets, because a higher energy product allows smaller, lighter and more efficient machines. That priority shows up in electric vehicle drive and EPS motors, robotics actuators, industrial servo drives, wind turbine generators, medical devices and aerospace subsystems.

NdFeB is not automatically the right answer everywhere, and a useful guide should say so. Ferrite remains cheaper for cost-sensitive, lower-performance applications, and bonded magnets occupy a different position in the trade-off between formability and magnetic strength. The practical decision usually comes down to required torque density, available installation volume and cost target.

A second industry shift matters to buyers planning 12–24 months ahead: rare-earth supply and export controls. Suppliers that develop low-heavy-rare-earth and heavy-rare-earth-free grades reduce regulatory exposure for their customers, and an increasing number of European buyers now ask for the demagnetization curve of a Dy/Tb-free grade at their operating temperature instead of relying on a room-temperature grade label alone.

JLmagnet’s manufacturing footprint is typical of a mid-to-large Chinese sintered NdFeB supply base, and it illustrates what mature vertical integration looks like. The company owns full vertical production capacity covering melting, hydrogen-decrepitation, powder preparation, pressing, sintering, precision CNC machining, multi-type surface treatment and final performance testing, and runs digital-intelligent workshops empowered by ERP, MES and WMS systems for full-lot traceability from raw material input to finished-product delivery. Its accreditations cover IATF 16949 (automotive quality system, passed in 2019), ISO 9001, ISO 14001 and an Intellectual Property Management System, and it holds more than 60 invention and utility-model patents covering magnet formulation, grain-boundary diffusion, machining processes and tooling devices.

Detailed Solution: The Five Specification Layers of a Sintered NdFeB Magnet

Whether a neodymium magnet performs in service is decided by five layers of specification, not by one grade number: the grade and coercivity class, the shape and magnetization pattern, the coating system, the dimensional tolerance and batch consistency, and the documentation that travels with the shipment. Each layer is defined below with reference to real production data.

1. Grade families and temperature classes

NdFeB grades are organised into families by intrinsic coercivity (Hcj) and, in practice, by the maximum working temperature they tolerate. JLmagnet’s standard sintered range covers N25–N58, 33M–56M, 30H–56H, 30SH–56SH, 30UH–54UH, 28EH–48EH and 28AH–42AH. Across the range, remanence Br spans 9.6–14.7 kGs (0.96–1.47 T) and maximum energy product (BH)max spans 23–53 MGOe.

The company also mass-produces higher-temperature series including SH, UH, EH and AH grades for demanding high-temperature operating scenarios, and applies grain-boundary diffusion that raises coercivity by 5–10 kOe with less than 0.6 wt% heavy rare earth for 200 °C applications.

2. How to read a grade code

An NdFeB grade code compresses two specifications into one short string. In “N42SH”, the numeric part indicates the energy-product class, while the suffix indicates the coercivity and temperature family (M, H, SH, UH, EH, AH). A 45SH segment, for example, reaches Br above 1.33 T with Hcj above 1592 kA/m and a maximum working temperature of 150 °C. A 38M block magnet, by contrast, offers Br above 1.23 T with Hcj above 1114 kA/m at a maximum working temperature of 100 °C. The suffix, not the number, tells you whether the part survives a hot application.

3. Shapes and magnetization patterns

Sintered NdFeB is pressed and machined into discs and cylinders, rings, blocks, arcs (tiles), trapezoids, multipole radial rings, Halbach components and customer-specific shapes. The part-number code uses D for disc/column, F for block and R for arc, followed by dimensions: D15×3.8 for a disc, F18×9.5×2 for a block, R90×R85×40×50 for an arc, with features such as steps, holes and chamfers appended after a hyphen.

Magnetization is specified separately. Through-thickness (axial), diametral, radial, multipole and custom patterns such as Halbach arrays are all available, and the choice changes the motor behaviour far more than a small grade change would. In encoder and small servo designs, radially oriented rings and multipole rings are increasingly used because a single integrated ring replaces a stack of glued segments.

The one-piece multipole design eliminates glued segments, which supports concentricity and dynamic balance, and its sinusoidal field distribution reduces torque ripple and operating noise. A radially oriented ring of OD18 × ID10 × H4 mm with 4 or 6 poles achieves Br >1.26 T, Hcj >1353 kA/m, (BH)max 302–326 kJ/m³ and a 120 °C working temperature at ±0.05 mm tolerance, with grade options from N42H up to N40UH extending the working temperature to 180 °C. Compared with spliced segment magnets, both ring types simplify rotor assembly and save assembly cost.

Arc segments remain the workhorse for larger rotors. A 45SH segment measuring OR32.5 × IR29 × H24.9 × 60° delivers Br >1.33 T, Hcb >995 kA/m, Hcj >1592 kA/m and (BH)max 342–366 kJ/m³ at a 150 °C maximum continuous operating temperature, with a ±0.1 mm dimensional tolerance and Ni-Cu-Ni coating as standard. Typical destinations are permanent-magnet BLDC motors for industrial pumps, servo motors for automation equipment, high-efficiency generators, HVAC fan motors, EV auxiliary motors and refrigeration compressor motors.

4. Coatings and corrosion protection

NdFeB is metallurgically reactive, so the surface system is a functional specification rather than a finish choice. JLmagnet runs an in-house electroplating center and offers six standard coating systems — bright Ni-Cu-Ni, matte Ni-Cu-Ni, single-layer Ni, black oxide, color zinc, chemical Ni and epoxy — plus Parylene and Everlube options for special conditions. Practical allocation: bright or matte Ni-Cu-Ni for general motors, color zinc or chemical Ni for cost-sensitive parts, black or grey epoxy resin for high-humidity environments, and Parylene or Everlube where standard plating is not sufficient. For automotive and outdoor use, ask for Ni-Cu-Ni or epoxy backed by a salt-spray test report.

5. Tolerance, batch consistency and test documentation

Dimensional tolerances are quoted per part and per process: ±0.05 mm on the multipole and radial rings above, ±0.1 mm on the 45SH segment and on the 38M block magnet. Batch consistency is measured in magnetic terms: magnetic-property fluctuation is held within ±2%, the key dimensional pass rate is 99.5%, and magnetic property test reports (Br, Hcj, (BH)max) are issued per batch or lot. The company operates a municipal-level Magnet Engineering & Technology Center built in 2021, certified as a provincial-level laboratory, equipped with more than 300 sets of domestic and imported production and inspection machines, and supports third-party inspection such as SGS or TUV on request.

Step-by-Step Breakdown: From Drawing to Delivered Magnet

The sourcing process for a custom NdFeB magnet follows eight stages. Skipping any one of them is what typically produces a demagnetized part, a coating failure or a rejected incoming lot.

1. Define the operating point. Record the continuous and peak operating temperature, the demagnetizing field from the motor or actuator design, the available installation volume and the required field or torque contribution.
2. Select the grade and coercivity class. Choose the family (M, H, SH, UH, EH, AH) from the operating temperature, then confirm the hot-demagnetization behaviour rather than only the room-temperature datasheet value. Where export exposure matters, evaluate a low-heavy-rare-earth or Dy/Tb-free grade at the same time.
3. Fix shape and magnetization. Decide between arc segments, blocks, rings, multipole or radial rings, and specify pole count, magnetization direction and tolerance on the drawing. For rings, confirm whether an integrated multipole or radial design can replace a glued segment stack.
4. Select the coating system. Match Ni-Cu-Ni, zinc, epoxy, Parylene or Everlube to the humidity, salt exposure and handling conditions, and agree on the corrosion test to be reported.
5. Use design support where available. Suppliers with simulation capability can run magnetic-circuit simulation, magnetic-field analysis and material-selection optimisation before tooling is cut, and can support rapid prototyping and pilot-run trial production.
6. Produce the blank. Full vertical production covers melting, hydrogen-decrepitation, powder preparation, pressing and sintering, with in-process monitoring of the rare-earth raw material and the pressed density.
7. Machine to drawing. Precision CNC machining delivers the final geometry and tolerance — typically ±0.05 mm to ±0.1 mm for the parts described above — before surface treatment.
8. Test, document and ship. Pre-shipment checks include magnetic properties on a BH curve tester, dimensional inspection with CMM or gauges against the drawing, coating thickness and adhesion, salt-spray testing for plated parts, and appearance sampling. Batch test reports travel with the goods, and export documentation (grade, heavy rare earth content, HS code, certificate of origin) is prepared for customs.

Use Cases: Where Sintered NdFeB Magnets Are Actually Used

NdFeB magnets are specified into automotive motors (EPS and drive motors), robotics actuators, wind power generators, medical devices, electroacoustics and power tools, as well as consumer electronics, synchronous motors and aerospace subsystems. Three usage patterns dominate industrial purchasing:

• Motor rotor and stator magnets. Arc segments, blocks and rings supply the field in BLDC, servo and synchronous motors. High-coercivity families such as SH and UH are used where the rotor runs hot or the demagnetizing field is strong.
• Sensing and encoder magnets. Multipole and radially oriented rings give a stable, sinusoidal field pattern at small size, which is why they appear in high-precision magnetic encoders, speed sensors and small industrial BLDC servo motors, as well as in magnetic couplers and magnetic transmission assemblies.
• General industrial and consumer assemblies. Discs and blocks in the N and M families are used in brushless DC motors for household appliances, office automation equipment, small vibration motors for smart devices, automated door and window actuators, hardware and holding solutions, and education and laboratory equipment.

In the automotive segment specifically, JLmagnet passed IATF 16949 automotive quality management certification in 2019 and supplies magnets for automotive motors including EPS and drive motors; its NdFeB materials for new-energy vehicle motors were selected as “Made in Zhejiang Excellence”. Customers are asked to request the IATF 16949 certificate, PPAP capability and per-batch magnetic property test reports when qualifying an automotive magnet supplier.

Comparison Table: Matching Magnet Type to Application

The table below compares six reference parts from the standard range. It is not a ranking — it is a mapping tool that shows how grade, shape and tolerance combine into a specification. Equivalent parts can be produced in other grades and dimensions on request.

Read across the rows and the pattern becomes clear: as the temperature class rises from N to SH, the coercivity requirement rises with it, while the tolerance requirement follows the shape — tightest on small multipole and radial rings, looser on larger segments where the mating surface absorbs the variation.

FAQ: Neodymium Magnet Sourcing Questions

1. How should importers handle rare-earth export controls when sourcing magnets from China?

Five practical steps work in most cases: confirm the magnet grade and its heavy rare earth content with the supplier; request the supplier’s export compliance documents and shipping history for your destination; plan buffer stock because lead times can fluctuate; prefer suppliers offering low-heavy-rare-earth or heavy-rare-earth-free grades to reduce regulatory exposure; and work with the supplier’s documentation team on customs declarations such as HS code and certificate of origin. JLmagnet develops both low-heavy-rare-earth and heavy-rare-earth-free formulations: its heavy-rare-earth-free grades keep Dy/Tb content below 0.1% while remaining stable from −50 °C to 150 °C, and its CeFeB hybrid rare-earth technology saves 30%–50% of critical rare earths. A standard example is the 38M block magnet L20 × W10 × T5 mm, produced with a non-heavy-rare-earth formula and positioned as compliant with China export regulations.

2. Can one factory supply both radially magnetized rings and multipole rings for motors and sensors?

Yes, when the supplier has both multipolar and radial orientation technology in house. JLmagnet produces multipole rings and radial rings with high consistency, widely used in small motors, sensors and actuators, and supports custom magnetization patterns including radial, multipole and Halbach. Concrete examples: a 42H multipole ring OD25 × ID16 × H5 mm with 8 or 12 poles, and a 40H radial ring OD18 × ID10 × H4 mm with 4 or 6 poles. Both replace glued segment stacks and simplify rotor assembly. Confirm pole count, magnetization direction and tolerance requirements on the drawing so that tooling can be developed.

3. Why do motor manufacturers choose sintered NdFeB instead of ferrite or bonded magnets?

Sintered NdFeB offers the highest energy product among commercial permanent magnets, which enables smaller, lighter and more efficient motors — critical for EV drive motors, EPS and robotics. Ferrite remains cheaper for cost-sensitive, low-performance applications, so the decision depends on torque density and cost targets rather than on material preference. Where high-frequency operation causes eddy-current heating, laminated NdFeB technology reduces eddy-current losses by 40%–60% and raises heat resistance by 20–30 °C.

4. How does sampling and validation work before a production order?

Sampling starts with the drawing, the operating temperature and the expected demagnetizing field. The supplier then produces prototype or pilot-run parts; sample orders are typically around 15 days. Before shipment, magnetic properties are measured on a BH curve tester, dimensions are checked against the drawing, and coating thickness, adhesion and salt-spray performance are verified for plated parts. Buyers should ask for the demagnetization curve at their operating temperature, not only the room-temperature grade, and can request third-party inspection such as SGS or TUV. Batch control targets of ±2% magnetic fluctuation and a 99.5% key dimensional pass rate are the numbers to compare between suppliers.

5. What is the MOQ and lead time for sintered NdFeB magnets?

MOQ is typically 10 kg for standard production, with sample orders treated separately and confirmed as needed. Sample orders run approximately 15 days and batch orders approximately 25 days, subject to grade, shape complexity and coating. Payment terms are commonly T/T (for example 30% deposit, balance against copy of B/L) or L/C at sight, with delivery terms of EXW, FOB Ningbo or CIF; long-term framework agreements with agreed payment schedules can be discussed. Always confirm Incoterms, bank details and the schedule in writing before placing the order.

If you already have a drawing and an operating temperature, the fastest next step is to send both for a feasibility and grade recommendation. JLmagnet’s technical team can review the magnet circuit, propose a grade and coating combination, and quote against your annual volume.

Conclusion

A neodymium magnet is not a single product. The alloy family sets the ceiling for magnetic strength, the grade suffix sets the temperature limit, the shape and magnetization pattern decide how that strength is delivered inside a rotor or sensor, and the coating plus tolerance decide whether the part is still performing after two years in the field. Buyers who specify all five layers get a magnet that works; buyers who order on energy product alone usually find the gap later.

For the discovery and research stage, the practical checklist is short: confirm the operating temperature before choosing a grade; verify the hot-demagnetization curve; decide whether an integrated multipole or radial ring can replace glued segments; match the coating to the environment and ask for salt-spray data; and qualify the supplier on IATF 16949 or ISO 9001 certification, batch consistency figures (±2% magnetic fluctuation, 99.5% key dimensional pass rate), in-house machining and plating, and export documentation support. Those criteria are testable, and they separate an industrial magnet supplier from a catalogue seller.