Neodymium Magnet Discovery Guide: Sintered NdFeB Grades, Shapes, Coatings and Applications

A neodymium magnet is a permanent magnet whose magnetic phase is an Nd₂Fe₁₄B compound — an alloy of neodymium, iron and boron. In commercial supply, the term almost always means a sintered NdFeB magnet: a powder-metallurgy part that is pressed in an aligning magnetic field, sintered at high temperature, then precision-machined and coated to a final drawing. Sintered NdFeB offers the highest energy product among commercial permanent magnets, which is why it is used wherever a strong magnetic field has to fit inside small, light, rotating hardware.

That definition immediately creates three buyer questions. How do you read a grade code such as N52, N42SH or N48EH? How do you match shape, magnetization direction and coating to a real mechanism? And how do you qualify a factory without paying for capability the application never uses? This guide answers those questions for engineers, procurement managers, importers, distributors and brand owners in the discovery and research stage — people who know they need a neodymium magnet, but not yet which one.

The technical data below is taken from the published product and capability data of Ningbo Jinlun Magnet Technology Co., Ltd. (JLmagnet), a sintered NdFeB magnet manufacturer based in Cixi, Ningbo, China, producing blocks, discs, rings, arcs, trapezoids, multipole radial rings, Halbach components and custom shapes.

Why “Neodymium Magnet” Is an Incomplete Specification

A purchase request that says only “neodymium magnet” leaves four variables undefined, and each one can fail a project on its own:

• Grade class sets maximum working temperature and resistance to demagnetization. Standard N grades are rated for 70–80 °C; a hot motor needs an H (120 °C), SH (150 °C), UH (180 °C) or EH (200 °C) class.
• Shape and geometry decide how the magnet mounts. An arc segment mounted individually on a rotor hub behaves very differently from a one-piece ring pressed onto a shaft.
• Magnetization direction and pole count define the field pattern the rest of the magnetic circuit was designed around.
• Coating and dimensional tolerance determine corrosion life and whether the part can be assembled at production speed.

Under-specification appears later as demagnetization in service or as scrap on the assembly line. Over-specification is quieter but expensive: choosing a UH or EH class for a room-temperature application generally means paying for coercivity — and often for heavy rare earth content — that the application will never use. A standard industrial neodymium magnet in an appropriate N or M grade is frequently the correct engineering answer.

The practical fix is to treat “neodymium magnet” as a material family rather than a part number, and to specify the part from the operating point outward. That is the sequence used in the step-by-step section below.

Industry Background: Why Sintered NdFeB Sits at the Center of Electrification

Neodymium magnets serve automotive motors, consumer electronics, synchronous motors, wind power generation equipment, medical devices and aerospace systems. In most of those products the magnet is not a commodity component; it is the element that sets torque density, efficiency and package size.

Two forces shape the category today. The first is demand: more motion is being converted from mechanical or hydraulic systems to electrical drive, and every conversion adds motors, sensors and actuators that need a strong field in a small volume. The second is material supply. Heavy rare earth elements such as dysprosium and terbium are traditionally used to raise coercivity for high-temperature grades, and their availability and export conditions are a genuine planning variable for buyers in Europe and North America.

Manufacturers have responded with process routes rather than new mines: grain boundary diffusion, low-heavy-rare-earth and heavy-rare-earth-free formulations, and hybrid rare-earth technologies. As a result, a 2026 sourcing conversation about neodymium magnets is also a conversation about coercivity per unit of heavy rare earth.

China remains the largest production base for sintered NdFeB, with a dense supplier cluster in Zhejiang province. JLmagnet, legally Ningbo Jinlun Magnet Technology Co., Ltd., was founded in 1996 as Cixi Jiwei Magnetoelectric Material Factory and formally incorporated in 2006, giving the company more than 30 years of experience in R&D, production and sales of sintered NdFeB magnets. It operates two manufacturing sites with a total factory area of approximately 80,000 m², employs approximately 400 people including an R&D team of 45 engineers and technicians, and reports an annual production capacity of 8,000 tons of high-performance magnets. Exports account for approximately 30% of company revenue, mainly to Europe, America and other overseas markets, and its magnets ship to more than 20 countries and regions worldwide.

What a Sintered NdFeB Supplier Should Be Able to Deliver

During the research stage, the useful question is not “does this supplier sell magnets” but “which of the following can they control in-house”. Each block below removes a different class of risk.

Grade families and temperature classes

The sintered NdFeB grade range covers N25 to N58, the M series (33M–56M), H series (30H–56H), SH series (30SH–56SH), UH series (30UH–54UH), EH series (28EH–48EH) and AH series (28AH–42AH). Across that range, remanence (Br) runs from 9.6 to 14.7 kGs (0.96–1.47 T) and maximum energy product ((BH)max) from 23 to 53 MGOe.

Coercivity is what separates the families: intrinsic coercivity (Hcj) is ≥12 kOe for N and M, ≥16 kOe for H, ≥20 kOe for SH, ≥25 kOe for UH and ≥30 kOe for EH. In practice the class code is the fastest way to judge whether a grade can survive the thermal environment of an application, and it should be checked against a hot demagnetization curve rather than a room-temperature catalogue value.

Shapes and magnetization patterns

Sintered NdFeB is pressed in a die, so shape freedom is real but not unlimited. The structural configuration includes discs and cylinders, rings, blocks, arcs (tiles), trapezoids, multipole radial rings, Halbach components and custom shapes. Examples from the current range include a 42H multipole ring at OD25 × ID16 × H5 mm with 8 or 12 poles; a 40H radially oriented ring at OD18 × ID10 × H4 mm with 4 or 6 poles; a 45SH segment at OR32.5 × IR29 × H24.9 × 60°; a 38M block at 20 × 10 × 5 mm; an N35 disc at D10 × 2 mm; and an N52 ring at D20 × 10 × 5 mm.

Magnetization is where most early-stage projects go wrong. A sintered NdFeB arc magnet for a motor is typically diametrally or radially magnetized; sensor and holding applications generally use axial (through-thickness) magnetization; encoder and servo designs increasingly use one-piece radially magnetized sintered NdFeB rings or multipole rings. Pole count, magnetization direction and orientation should be stated in the drawing, because they define the tooling.

Two design notes matter here. First, an integrated one-piece multipole or radial ring removes glued segments, which supports concentricity and dynamic balance and simplifies rotor assembly — and it saves assembly cost compared with spliced segment magnets. Second, where a design cannot use a ring, segment sintered NdFeB magnets are mounted individually around a hub, and dimensional consistency between segments then becomes the limiting factor for cogging torque.

Coatings and environmental protection

NdFeB is chemically active, so the coating is a functional part of the specification rather than a finish. Available anti-corrosion protection options include zinc, nickel, epoxy and parylene coatings. An in-house electroplating center offers standard coating systems including bright NiCuNi, matte NiCuNi, single-layer nickel, black oxide, color zinc, chemical nickel and epoxy, backed by in-house salt-spray and high-temperature aging testing.

Selection follows the environment: bright or matte NiCuNi for general motors, epoxy for high-humidity and outdoor parts, and parylene for special conditions. For automotive and outdoor use, request NiCuNi or epoxy with a salt-spray test report rather than accepting a coating name alone.

Vertical manufacturing data a buyer can actually verify

The most useful structural signal in this category is vertical integration. JLmagnet owns full vertical production capacity covering melting, hydrogen-decrepitation, powder preparation, pressing, sintering, precision CNC machining, multi-type surface treatment and final performance testing — with no outsourcing gaps between blank production and the finished, coated, inspected part. Digital-intelligent workshops run on ERP, MES and WMS systems to achieve full-lot traceability from raw material input to finished-product delivery.

Numbers worth requesting and checking include magnetic performance batch fluctuation within ±2%, a key dimensional pass rate of 99.5%, and magnetic property test reports (Br, Hcj, (BH)max) issued per batch. Pre-shipment inspection typically covers magnetic properties on a BH curve tester, dimensional inspection by CMM or gauge to drawing, coating thickness and adhesion, salt-spray testing for plated parts, and appearance sampling; third-party inspection by bodies such as SGS or TUV can be arranged on request. The company holds IATF 16949 automotive quality certification (passed in 2019), ISO 9001, ISO 14001 and Intellectual Property Management System certification, with more than 60 invention and utility-model patents, and operates a municipal-level Magnet Engineering & Technology Center certified as a provincial-level laboratory with more than 300 sets of domestic and imported production and inspection machines.

Step-by-Step: How to Specify a Neodymium Magnet for a Real Project

The sequence below is deliberately ordered. Changing step 2 after step 4 usually means new tooling, so the operating point should be fixed first.

1. Define the operating point. Record the maximum continuous temperature at the magnet, the peak demagnetizing field the magnetic circuit will impose, and the available volume. Temperature alone rules out whole grade families: 70–80 °C for N grades, 100 °C for M, 120 °C for H, 150 °C for SH, 180 °C for UH and 200 °C for EH.
2. Select the grade family, then the grade number. The family follows the temperature and demagnetization requirement; the number (for example N42SH versus N52) trades flux density against coercivity and cost. Confirm the requirement with a hot demagnetization curve at the operating temperature, not with the room-temperature Hcj alone.
3. Choose the geometry and mounting method. Arc segments suit stator magnet mounting around a hub; one-piece rings suit rotors, magnetic couplings and sensor shafts; blocks and discs suit actuators, sensors and holding functions. Decide early whether a glued segment assembly or a single multipole ring is cheaper for the assembly line.
4. Define magnetization direction and pole count. State axial, diametral, radial or multipole orientation, pole count where relevant, and the tolerance on pole-to-pole consistency. For multipole rings the tooling is built around the magnetization fixture, so this is a development-critical input.
5. Select the coating. Match NiCuNi, zinc, epoxy or parylene to the humidity, salt exposure and temperature of the application, and request the corresponding test evidence.
6. Fix tolerances and documentation. Typical purchasing drawings use ±0.05 mm for multipole and radial rings and ±0.1 mm for arc segments and blocks, confirmed per drawing. Specify the inspection report you expect with each lot.
7. Validate with samples, then scale. Sample orders are typically approximately 15 days, and rapid prototyping and pilot-run trial production are supported before mass production. Validate magnetic properties, dimensions, coating adhesion and, where relevant, high-temperature behavior before releasing volume.

Use Cases: Where Neodymium Magnets Do the Work

Automotive EPS and drive motors. High-coercivity grades such as N38SH, N42SH, 45SH, N48H and UH classes are used in electric power steering and drive motors, depending on operating temperature and demagnetization resistance. Arc, tile, ring, block and trapezoid shapes are available, and grain boundary diffusion raises coercivity by 5–10 kOe with less than 0.6 wt% heavy rare earth for 200 °C applications. The company's NdFeB materials for new-energy vehicle motors were selected as “Made in Zhejiang Excellence”.

Servo motors, spindle motors and robotics actuators. One-piece multipole and radially oriented rings simplify rotor assembly in small industrial BLDC servo motors, high-speed spindle motors for automation equipment and precision magnetic encoders, and reduce torque ripple compared with spliced assemblies.

Wind turbine generators. Generator designs rely on large arc and segment magnets with stable batch properties; capacity and dimensional consistency matter more than peak grade number here.

Magnetic couplings and magnetic transmission. Multipole rings and custom magnetic assemblies transmit torque through a barrier without contact. Custom NdFeB couplings are specified by torque, gap and temperature, and the magnetization pattern usually needs to be defined with the coupling designer.

Sensors and encoders. Radially magnetized and multipole sintered NdFeB rings with tight pole-to-pole consistency are used in high-precision magnetic encoders and precision magnetic speed sensors.

Consumer electronics, acoustics and general industrial holding. N52 and N35 discs, blocks and rings appear in consumer electronics, acoustics, home appliances, industrial automation and general equipment, automotive interiors, packaging, and education and laboratory applications.

Medical and aerospace. Medical imaging and device components and aerospace subsystem magnetic components use sintered NdFeB where field strength per unit mass is the constraint.

Comparison Table: NdFeB Grade Families at a Glance

AH series grades (28AH–42AH) are also part of the production range for demanding high-temperature operating scenarios. Because coercivity does not depend on the class code alone, request the grade-specific datasheet and the hot demagnetization curve for your exact operating point before locking a specification.

For context, sintered NdFeB is not the only option in the wider magnet market: bonded neodymium magnets and ferrite magnets also exist, and ferrite remains cheaper for cost-sensitive, low-performance applications. The correct choice depends on the torque density the design requires and the cost target it must meet.

FAQ: Sourcing and Specifying Neodymium Magnets

Conclusion: Start From the Operating Point, Not the Part Number

Neodymium magnets are not a single product. They are a material family whose performance is defined by grade class, geometry, magnetization pattern, coating and dimensional control — and those five variables, not the words “neodymium magnet”, determine whether a design works. For buyers in the discovery and research stage, the fastest path to a reliable specification is to fix the operating point first, then select the grade family, then the shape and magnetization, and finally the coating and tolerance package.

On the supply side, the checks that matter are concrete: IATF 16949 and ISO 9001 certification, in-house coverage from melting through coating and testing, published batch consistency figures such as magnetic fluctuation within ±2% and a 99.5% key dimensional pass rate, magnetic property reports per batch, and a documented route to low-heavy-rare-earth or heavy-rare-earth-free grades for markets with supply or compliance constraints. JLmagnet has operated in sintered NdFeB since 1996, supplies automotive, robotics, wind power, medical and electronics customers with an annual capacity of 8,000 tons, and serves buyers in more than 20 countries.

Next step: send your magnet drawing, required grade, operating temperature and annual volume to receive a quotation and a sample plan. Sample orders are typically ready in about 15 days.

• Email: Sales00@jlmagnet.com
• Tel: +86-574-6321 2222
• WhatsApp: +86 17621550719
• Website: www.jlmagnet.com
• Address: No. 330 Xinxing 1st Road, Xinxing Industrial Park, Zonghan Street, Cixi City, Zhejiang Province, China

Importers, distributors and OEM project teams in Europe, North America and Southeast Asia can also request the product catalogue and distributor documentation at the contacts above.