What the number tells you

N42 means a nominal (BH)max of about 42 MGOe, roughly 334 kJ/m³; one supplier's datasheet lists 334 kJ/m³ as the typical value [3]. It describes how much magnetic energy the material can deliver, so a higher number means a stronger material. It does not say how hard a particular magnet will pull, because pull force also depends on size, shape, the air gap and what the magnet touches (see why the datasheet pull force is not the force you get). Values for the same grade differ a little between suppliers, and even between tables on one page: one supplier lists N42 at 13,150 G and 42 MGOe and N42SH at 13,100 G and 41 MGOe in one table, and both at 12,800 G and 42 MGOe in another [1]. Treat the grade as a class, and ask for the datasheet of the material you are actually buying.

What the letters tell you

The letters stand for a minimum intrinsic coercivity. One manufacturer's guide gives these minimums: no letter, 12 kOe; M, 14 kOe; H, 17 kOe; SH, 20 kOe; UH, 25 kOe; EH, 30 kOe; AH, 35 kOe [2]. Supplier tables turn the classes into reference working temperatures: 80 °C for no letter, 100 °C for M, 120 °C for H, 150 °C for SH, 180 °C for UH, 200 °C for EH and 220–230 °C for AH [1], [4]. The AH figure differs between tables, and some suppliers list N52 lower, at 60–70 °C [1], [3].

Why the temperature figure is only a starting point

These temperatures are reference values, not limits you can read off for every part. One supplier states that the maximum working temperature depends on the circuit in which the magnet operates, that its figure applies at a length-to-diameter ratio of 0.7, and that customers should consult the manufacturer for applications near 150 °C [3]. Another notes that size and shape also affect performance at high temperature [4]. In general, a thin disc magnetized through its thickness works at a lower permeance than a long cylinder, and can lose strength permanently at a lower temperature than the same grade in a longer shape.

Heat also shrinks the margin itself. For grade N35, one manufacturer lists reversible temperature coefficients of about −0.12 %/°C for Br and −0.618 %/°C for Hcj, measured between 20 and 80 °C [5]. In relative terms, coercivity falls about five times faster than strength as the magnet warms up. The practical check is the demagnetization curve at your operating temperature, for your magnet's dimensions. One manufacturer shows N42 and N42SH side by side at a reverse field of 15 kOe: N42 is pushed into the non-linear part of its curve, while N42SH stays linear and returns to its original Br once the field is removed [2].

A higher number is not always the better buy

One supplier puts N52 at about 20% more powerful than N42, at up to twice the price, and notes that two N42 magnets can be more useful than one N52 where space allows [4]. Some tables also give N52 a lower working temperature than N42 [1], [3]. So choose the number from the force you need and the space you have, and choose the letters from the temperature and from any opposing fields, such as those in motors or next to other magnets. Our articles on grades for high-temperature motors and where dysprosium and terbium matter cover the higher classes in more detail.

What to put in your enquiry

Write the full grade, for example N42SH, not just N42. Add the operating temperature range and the peak temperature, the dimensions, how the magnet sits in the assembly, and any opposing fields. If you do not know the grade, describe the temperature and the job and we will propose one. The rest of the checklist is in our RFQ guide, and the temperature selector maps your range to a material.

References

[1] Stanford Magnets. Neodymium magnets grade info. https://www.stanfordmagnets.com/neodymium-magnets-grade-info.html (accessed 21 October 2026)

[2] Advanced Magnets. How to understand the rare earth permanent magnets grades, part 1: sintered neodymium iron boron magnets. https://www.advancedmagnets.com/how-to-understand-the-rare-earth-permanent-magnets-grades-part-1-sintered-neodymium-iron-boron-magnets (accessed 21 October 2026)

[3] Eclipse Magnetics. Neodymium grades data (datasheet, PDF). https://www.eclipsemagnetics.com/site/assets/files/2399/neodymium_grades_data.pdf (accessed 21 October 2026)

[4] First4Magnets. Grades of neodymium magnets. https://www.first4magnets.com/neodymium-magnet-information/grades-of-neodymium-magnets (accessed 21 October 2026)

[5] Arnold Magnetic Technologies. Arnold Neo catalog (PDF). https://www.arnoldmagnetics.com/wp-content/uploads/2019/06/Arnold-Neo-Catalog.pdf (accessed 21 October 2026) [Supplier technical pages and datasheets, not the IEC standard; values vary by supplier.]

What it has meant in practice

Licensing has been uneven. Chinese magnet exports fell sharply in spring 2025, then recovered once controls eased, and analysts report that some markets, Europe among them, were supplied far better than others [1], [2]. The real pinch point is not mining but processing and qualification, and China handles the large majority of heavy rare earth processing [2], [3]. Small quantities of dysprosium-based materials were reported to dry up even when headline export figures looked healthy [2].

Who is exposed, and who is not

Grades that rely on dysprosium or terbium (high-temperature neodymium) and samarium cobalt feel it first. Standard neodymium grades used at moderate temperatures need little or no heavy rare earth, and ferrite and AlNiCo contain no rare earths of this kind at all.

What to do about it

Ask for lead time and licence status in every quote, and order earlier for high-temperature neodymium and SmCo. Specify the temperature grade you really need, not the highest one (see our guide on choosing a material by temperature). Qualify an alternative grade or a second source before you need it. Where the force and space allow, consider ferrite. And if you tell us your temperature range and volumes, we will tell you which grades carry supply risk right now.

References

[1] CSIS. (2026). Rare earth export restrictions one year later. Center for Strategic and International Studies. https://www.csis.org/analysis/rare-earth-export-restrictions-one-year-later

[2] S&P Global. (2026, January 27). Rare earth supply bottlenecks set to persist in 2026. https://www.spglobal.com/energy/en/news-research/latest-news/metals/012726-rare-earth-supply-bottlenecks-set-to-persist-in-2026

[3] Tech Times. (2026, October 2). Rare earth magnets: China's November 10 deadline and the US gap money can't close. https://www.techtimes.com/articles/328392/20261002/rare-earth-magnets-chinas-november-10-deadline-us-gap-money-cant-close.htm

Where they matter

Traction and servo motors, generators, and any assembly where the magnet sits next to a hot winding or in a strong reverse field. The letters after the grade number (H, SH, UH, EH) indicate higher coercivity and operating temperature [1]. Reaching them generally takes more dysprosium or terbium, which adds cost [1].

Where they don't

Holding magnets, sensors at room temperature, sound devices, small motors that do not run hot, and everyday uses such as the magnets in appliances [2]. Standard N-series grades are enough there, and over-specifying a high-temperature grade only adds cost and supply risk.

Ways to reduce exposure

First, work out the real maximum temperature and opposing field at the magnet's position, then choose the lowest grade with a safety margin. Second, ask suppliers about low-heavy-rare-earth or heavy-rare-earth-free grades. Third, note that samarium cobalt is not an escape route, because samarium is also under licence [3]. Ferrite is the only common option with no rare earths at all.

Our product table shows the grade range and the heavy-rare-earth-free option for each size. Send us your working temperature and we will suggest the lowest-risk grade.

References

[1] Wikipedia contributors. Neodymium magnet. Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/Neodymium_magnet

[2] S&P Global. (2026, January 27). Rare earth supply bottlenecks set to persist in 2026. https://www.spglobal.com/energy/en/news-research/latest-news/metals/012726-rare-earth-supply-bottlenecks-set-to-persist-in-2026

[3] Tech Times. (2026, October 2). Rare earth magnets: China's November 10 deadline and the US gap money can't close. https://www.techtimes.com/articles/328392/20261002/rare-earth-magnets-chinas-november-10-deadline-us-gap-money-cant-close.htm

The trade-off

Ferrite gives the least force per volume, so a ferrite part is larger than a neodymium part doing the same job. It also becomes more vulnerable to demagnetization in the cold rather than in the heat, which matters for outdoor and refrigeration uses.

Where it often wins

Wherever there is room for a larger magnet and cost matters: speakers, small DC motors and fans, holding and fastening, magnetic separators, sensors and signage. Flexible magnets (sheets, rolls and strips) are also ferrite-based, which is why their prices are far steadier than those of neodymium.

A quick test before switching

Check four things: the force you need, the space you have, the working temperature including the cold end, and whether the design can change. If the force target is modest and there is room, ferrite is usually the lowest-risk and lowest-cost option. If space is tight, stay with neodymium and manage the grade and the supply as described in our other articles.

We supply ferrite blocks, discs, rings and arcs as well as flexible magnet sheets, rolls and strips. Tell us the job the magnet has to do and we will say whether ferrite can handle it.

References

[1] Wikipedia contributors. Ferrite (magnet). Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/Ferrite_(magnet)

Neodymium (NdFeB): the strongest, with a limited heat range

Neodymium gives the most force for the least volume. Standard grades are suited to roughly 80°C; special high-temperature grades extend that to around 200°C, at the price of some strength. Like all magnets, its output dips as it warms (a reversible loss of roughly a tenth of a percent per degree), and beyond the grade's limit part of that loss becomes permanent. It also needs a coating to resist corrosion.

Samarium cobalt (SmCo): weaker, but steady when hot

At room temperature SmCo is not as strong as neodymium, but it holds its strength much better as the temperature rises and works up to about 350°C. It resists corrosion without a coating. The trade-offs are higher cost and brittleness. It is the usual answer for hot servo motors and sensors.

AlNiCo: the highest temperature, the lowest resistance to demagnetization

AlNiCo tolerates temperatures up to about 500°C and its strength changes very little with heat. Its weakness is the opposite: it can be weakened by a reverse magnetic field, or even by careless handling against steel. That is why it is usually made long and slender, and why it is found in measuring instruments and sensors rather than in holding applications.

Ferrite: cheap, corrosion-proof, weakest

Ferrite (ceramic) is the lowest-cost option, needs no coating and works up to about 250°C, but gives the least force per volume. Unusually, it becomes more vulnerable to demagnetization in the cold, not in the heat, so a low operating temperature matters for it.

How to choose

Write down the real minimum and maximum temperature at the magnet's location in the assembly, not the room temperature. Then pick the lowest-cost material that works with a safety margin. If you tell us that range and what the magnet has to do, we will recommend the material and grade.

Heat: reversible and permanent loss

Heating weakens a magnet in two ways. Within the grade's limit the loss is reversible: the magnet is weaker while hot and recovers when it cools. Above the limit, part of the loss is permanent and does not come back. The fix is a higher temperature grade and a margin, not just a match to the nominal temperature.

Opposing magnetic fields

A strong field pointing against the magnet's own, such as the current in a motor winding at peak load or another magnet repelling it, can weaken it permanently. This is a common cause of failure in motors, and it is one reason high-temperature, high-coercivity grades are specified there.

Shape matters

For the same material, a thin, flat magnet with large faces is more exposed to demagnetization than a tall, slender one, because its own field works harder against itself. A magnet that sits in a closed steel circuit is better protected than one standing alone in air.

Damage and corrosion

Chips, cracks and rust remove magnetic material. Uncoated or damaged neodymium corrodes in humid air, so the coating must suit the environment. Knocking magnets together during handling is a quick way to chip them.

What helps us prevent it

Tell us the temperature range, whether other magnets or windings are nearby, and how the magnet sits in the assembly. With that we can recommend a grade and a shape that stay stable over the life of the product.

The part itself

Dimensions with tolerances, or a drawing. For rings, arcs and countersunk parts, the inner and outer diameters, height and any hole or chamfer. If you already know the material and grade, include it; if not, describe what the magnet has to do and we will propose one.

How it works

The magnetization direction and, for multipole parts, the pole layout. The force or field you need and the air gap. The operating temperature range. The environment, such as humidity, oil or chemicals, because it decides the coating.

Commercial details

The quantity for the first order and the expected yearly volume. The delivery destination and whether you prefer air or sea freight, since air shipments need shielded packaging. Any packaging requirements and the certificates you need, for example RoHS, REACH or material certificates.

No drawing yet?

Send a sample or a photo with measurements, or simply the function: what it holds, how heavy it is, what it is mounted on. We would rather start from the function than guess a shape.

The air gap costs more than people expect

Holding force falls away much faster than intuition suggests as the gap opens. A coat of paint, a plastic housing, a label or a rough casting surface is already a gap, and at a few millimetres a small magnet may keep only a small fraction of its contact value. If anything sits between the magnet and the steel, the design should be calculated with that gap, not with the catalogue number.

The steel matters as much as the magnet

The datasheet assumes thick, low-carbon steel. A thin sheet saturates: the magnet's field cannot pass fully through it, so the usable force drops. Austenitic stainless steels are largely non-magnetic, and cast iron or high-carbon steels behave differently from mild steel. A rough, rusty or curved surface also reduces real contact area.

Pulling straight off is not the same as sliding

Most loads do not pull a magnet straight away from the surface; they try to slide it, as with anything hanging on a vertical wall. Sliding (shear) resistance depends on surface friction and is only a fraction of the straight pull value. For hanging loads, design on the shear value and apply a generous safety factor, higher still wherever a falling part could injure someone.

What to tell us when you ask for a magnet

Send us the real conditions: steel type and thickness, the gap, whether the load pulls or slides, and the operating temperature. With those four details we can recommend a size and grade that holds in your actual assembly, and where the margin is tight we will suggest testing samples before you commit to a volume order.

The orientations you will meet most often

Axial: the poles are on the two flat faces, so the field runs through the thickness. This is the usual choice for discs and blocks used for holding. Diametral: the poles sit on opposite sides of the curved surface, typical for a small magnet that rotates above a sensor to report an angle. Radial: the poles are on the inner and outer surfaces of a ring or arc, common in motor rotors. Multipole: several alternating poles on one part, used in encoders and some sensing rings.

Why it cannot simply be changed later

In most high-performance sintered magnets, the powder is aligned in a magnetic field while it is pressed, so a preferred direction is built into the material itself. After sintering, the part can only be magnetized strongly along that direction. That means the orientation has to be known when the order is placed; changing it later usually means a new production lot, not just a different magnetizing step.

Put it on the drawing

State which face is north, or the number and layout of poles for a multipole part, and say whether the magnets should be delivered magnetized or not. A single clear line on the drawing prevents the rework and returns that come from assuming the wrong default.

Sintered: maximum strength in minimum volume

Sintered magnets are pressed from powder, sintered, and then cut and ground to size. They deliver the highest magnetic strength for a given volume, which is why they dominate motors and demanding holding applications. The trade-off is shape: they are brittle, and anything beyond simple blocks, discs, rings and arcs becomes a grinding job that adds cost.

Bonded: shape freedom and consistency

Bonded magnets mix magnetic powder with a polymer binder and are moulded close to final shape. That allows thin walls, complex geometry and consistent dimensions in large quantities without extensive grinding, and they are less brittle. The price is magnetic strength, which is only a fraction of what a sintered magnet of the same volume provides, and the binder can limit the usable temperature for some types.

A simple way to decide

If the job is to produce as much force or field as possible from the smallest space, sintered is usually the answer. If the part has a complicated shape, a very thin wall, or must be made in high volume with tight consistency, bonded deserves a serious look. Tell us what the magnet has to do, not only what shape you think it should be, and we will suggest the route before any tooling is committed.

The rule in plain terms: UN 2807

Under IATA's Dangerous Goods Regulations, magnetized material is assigned UN number 2807. If the magnetic field strength measured at 4.6 metres (15 feet) from the surface of the package exceeds 0.00525 Gauss, the shipment is classified as Class 9 dangerous goods and subject to strict packaging, labeling and documentation rules before an airline will accept it. Packages that pass this test — because they are shielded or packed with enough separation and steel shielding to bring the field below that threshold — can usually ship as "excepted" from most of the formal dangerous goods process, but a written field-strength declaration is still standard practice.

What this looks like in practice

In practice, compliant magnet shipping means two things working together: a package design (steel shielding, keeper plates, spacing between magnets, orientation that cancels the external field) that physically brings the measured field below the regulatory limit, and the paperwork to prove it — a magnetic field strength test or declaration the airline's ground handling agent can check against. Get either one wrong and a shipment gets held at the origin airport, not at customs on arrival, which is the more disruptive and harder delay to explain to an end customer.

What we do on every air shipment

We pack magnetized material to IATA and IMDG requirements by default, not as a special request: shielded cartons, measured external field strength before the shipment leaves our facility, and the declaration documentation included with the airway bill. If a project needs a specific packaging configuration for an unusually strong or large magnet, tell us the grade and dimensions during the quote stage and we will confirm the shielding approach before production, not after the shipment is already built.

A second source has to be genuinely independent

Two distributors buying from the same mill are not a second source — they fail together. A real second source sits in a different country, under different export regulations, reachable by a different shipping route. That is the entire point of dual-sourcing: removing a single point of failure, not adding a second invoice.

Why Turkey fits that role for Europe and the Middle East

Turkey manufactures and imports neodymium, ferrite, samarium cobalt and AlNiCo magnets independently of any single supplier country, with direct land, sea and air routes into both Europe and the Middle East. For a buyer currently dependent on one overseas source, qualifying a Turkish supplier alongside it is one of the more practical ways to diversify geographic and regulatory exposure without redesigning anything.

Qualifying us costs you almost nothing to find out

You do not need to switch suppliers to find out whether this works. Send us your drawing and your current supplier's material certificate — grade, dimensions, coating, tolerance — and we will tell you plainly whether we can match it, and where we cannot. Many buyers who qualify a second source start with a small allocation, enough to keep the approval current and the relationship live, while their primary source continues to carry the bulk of the volume. That is a low-risk way to test us before you ever need to rely on us.

Standard vs. SH, UH and EH grades

A standard N42 magnet is rated for continuous use up to around 80°C. Once a motor's internal temperature regularly exceeds that — common in industrial drives, automotive actuators and continuously loaded servo motors — the magnet needs a higher temperature class: SH (150°C), UH (180°C) or EH (200°C).

Using an underrated grade in a hot motor doesn't just reduce output — it can cause partial, permanent demagnetization over time, which is expensive to diagnose after the fact.

Practical rule of thumb

When specifying magnets for a new motor design, always check the magnet's expected operating temperature under full continuous load (not just ambient temperature), and leave a safety margin of at least 20–30°C below the grade's rated maximum.

Nickel-Copper-Nickel (NiCuNi)

The most common coating. Good corrosion resistance for indoor, dry-to-moderate humidity environments, and relatively low cost. This is the default choice for most general industrial and consumer applications.

Epoxy

Adds a non-conductive, flexible outer layer, often over a nickel base. Better protection against chemicals and mild outdoor exposure, and reduces the risk of chipping on sharp-edged magnets.

Zinc

A more economical option than nickel, with moderate corrosion resistance. Common where cost matters more than long-term outdoor durability.

Gold / PVD coatings

Mainly cosmetic or used in specific electronics and jewelry applications, applied over a nickel base for corrosion protection with a decorative finish.

For marine, outdoor or high-humidity environments, we recommend discussing the exact conditions with us before ordering — coating choice can significantly affect service life.

Keep them apart during storage

Large magnets can snap together violently from a distance, trapping fingers or shattering the brittle magnet material on impact. Store them with spacers, in individual packaging, or in a way that prevents them from reaching each other.

Mind electronics and data media

Strong magnetic fields can damage credit cards, hard drives, pacemakers and sensitive electronic equipment. Keep a safe distance during storage and transport.

Two-person handling for large units

For magnets above a certain size and pull force, always use two people, or a controlled separation tool, rather than trying to slide them apart by hand.

If your team regularly handles large-format magnets, we're happy to share sizing-specific handling guidance for the exact products you're ordering.