A
- AlNiCo
- Aluminium-nickel-cobalt: excellent temperature stability but easily demagnetized; used in sensors, instruments and guitar pickups.
- Anisotropic vs isotropic
- Anisotropic magnets are oriented during pressing and are far stronger along one axis; isotropic can be magnetized in any direction - which is what makes flexible multipole patterns possible.
C
- Coating (NiCuNi, epoxy, parylene)
- NdFeB corrodes, so it is plated or coated; the coating choice governs outdoor and medical suitability.
- Coating qualification, tolerance class & edge break
- NdFeB rusts, so coatings are qualified by salt-spray hours, adhesion and thermal shock, with NiCuNi for general use, epoxy or zinc for cost, and parylene or full encapsulation for medical and implant-adjacent work. Alongside it sit the boring specs that decide yield: dimensional tolerance class, chamfer and edge break, and whether the coating thickness is inside the tolerance or on top of it.
- Coded (programmable) magnet
- A magnet whose face is printed with a designed pattern of magnetic regions, giving it engineered behavior.
- Coercivity (Hci)
- How strongly a magnet resists being demagnetized by heat or an opposing field.
- Countersunk mounting
- M4/#6 CTSK holes let coded pairs bolt into real assemblies.
- Curie temperature
- The temperature at which a magnet loses its magnetism entirely; the practical max working temperature is well below it.
D
- Demagnetization curve (second quadrant)
- The B-H and J-H curves in the second quadrant, where a permanent magnet actually operates. Hc (normal coercivity) is where flux density reaches zero; Hci (intrinsic coercivity) is where the magnet's own polarization is destroyed - the number that really predicts whether a magnet survives heat and opposing fields.
- Dysprosium & terbium
- Heavy rare earths added to raise coercivity so magnets survive heat; the scarcest, most supply-critical inputs.
E
- Easy axis & orientation direction
- An anisotropic magnet is pressed in a field so its grains share one preferred magnetic direction. That easy axis is locked in at pressing; the magnet can only be magnetized usefully along it, so orientation direction is a manufacturing decision made long before magnetization.
- Electropermanent magnet (EPM)
- A switchable assembly whose external field can be turned on or off - a different route to a 'programmable' magnet.
F
- Ferrite / ceramic magnet
- Low-cost, corrosion-resistant and weak - the highest-volume magnet by count, common in speakers and holding applications.
- Fragmented market
- Many small independent players, no dominant share — the precondition for a roll-up.
G
- Gauss & tesla
- Units of magnetic flux density (1 tesla = 10,000 gauss) - what a gaussmeter reads at the magnet's surface.
- Grain boundary diffusion
- Diffusing dysprosium or terbium along grain boundaries to raise heat resistance while using far less heavy rare earth.
H
- Halbach array
- An arrangement of magnets whose rotating orientation concentrates flux on one face and nearly cancels it on the other.
I
- Iron nitride & rare-earth-free magnets
- Iron-nitride (Fe16N2) is the most advanced attempt at a magnet with no rare earth at all, commercialized by Niron Magnetics; alongside it sit ferrite substitution, SmCo for heat, and magnet-free motor topologies such as externally excited synchronous machines. None yet matches NdFeB energy product, which is exactly why the substitution question stays open.
K
- Knee point & irreversible loss
- Above a certain temperature the demagnetization curve develops a knee. Push the operating point past it - by heat, an opposing field, or too aggressive a geometry - and the magnet does not recover when it cools: the loss is irreversible and only remagnetization restores it.
L
- Laminations, eddy-current loss & retaining sleeves
- Changing fields drive circulating currents in conductive magnets and steel, heating both; laminated stacks and segmented magnets break those loops. In high-speed rotors a carbon-fibre or Inconel retaining sleeve is added because sintered magnet is strong in compression and weak in tension and would otherwise fly apart.
M
- Magnet recycling
- Recovering rare earths (or reprocessing whole magnets) from end-of-life motors and drives, now a real Western feedstock route.
- Magnetic circuit, air gap & back iron
- Flux behaves like current in a loop: magnet, steel return path, air gap. The gap dominates the reluctance, so gap size governs usable field far more than grade does; flux that escapes the intended path is leakage and flux that bulges at the gap edges is fringing, and both steal from the working field. Back iron - a steel plate or cup behind the magnet - gives flux a low-reluctance route home and is the cheapest way to raise holding force, which is why the same magnet quoted bare and quoted in an assembly gives wildly different pull numbers. Drive the steel past saturation and the extra flux simply leaks.
- Magnetic coupling
- Transmitting torque through a sealed wall using magnet arrays instead of a shaft - the basis of leak-free pumps.
- Magnetic gear
- Contactless gearing via modulated magnet arrays: no teeth, no wear, inherent overload protection.
- Magnetic viewing film
- Hi-res film that reveals a magnet's coded pole pattern in visible color.
- Magnetize before vs after assembly
- Magnetized parts attract swarf, jump in fixtures and complicate bonding, so assemblies are often built with blanks and magnetized last through a fixture. Magnetize-after gives cleaner assembly and truer multipole registration; magnetize-before is sometimes forced by geometry or by the energy the fixture would need.
- Magnetizing fixture
- The tooled coil that imprints a specific pole pattern; the fixture, not the magnet blank, defines the pattern.
- Maxel
- A 'magnetic pixel' — one of the many small magnetic regions printed across a coded magnet's face.
- Maximum energy product (BHmax)
- The headline figure of merit for magnet strength, quoted in MGOe - the number grades are named for.
- Mine-to-magnet
- A fully integrated domestic chain from ore through separation, alloy and finished magnet - the stated goal of Western supply policy.
- MOQ, tooling/NRE and price per kilogram vs per piece
- Magnets are sold on alloy weight plus process, so quotes move between price per kilogram (which tracks the NdPr market) and price per piece (which buries tooling, magnetizing-fixture NRE, coating and QC). Custom shapes and custom pole patterns carry fixture NRE and a minimum order quantity, and long-term supply agreements or allocation are how large buyers hedge both price and availability.
- Multipole magnetization
- Writing several alternating north/south poles onto a single magnet - the industrial ancestor of coded magnets.
N
- N-grade (N35-N52)
- The NdFeB strength grade - the number tracks maximum energy product, so N52 is the strongest common grade.
- NdFeB (neodymium)
- Neodymium-iron-boron - the strongest commercial permanent magnet and the workhorse of modern motors and devices.
- NdPr oxide
- The neodymium-praseodymium oxide (didymium) that is the primary magnet feedstock and the main rare-earth price driver.
- Near-field vs far-field
- Coded patterns tune where a magnet grips (near) vs repels/springs (far).
P
- Permeance coefficient (load line)
- The slope of the magnet's operating point, set by its geometry and the circuit around it. A short, wide magnet sits on a low load line and is easy to demagnetize; a long, thin magnet in a closed circuit sits high and is stable. Change the geometry and you change the working strength without changing the grade.
- Pole pitch, cogging torque & skew
- Pole pitch is the arc or distance between adjacent poles. In motors, the interaction between magnet poles and stator slots produces cogging torque - a notchy reluctance ripple - which is suppressed by skewing the magnet or the stack, by pole-arc shaping, or by choosing slot/pole combinations that spread the effect.
- Polymagnet
- The programmable-magnet product/technology pioneered by Correlated Magnetics Research (CMR).
- Pot magnet / magnetic assembly
- A magnet in a steel cup or housing that redirects flux to one face, multiplying usable holding force.
- Pull force
- The straight-line force needed to pull a magnet off steel - the spec buyers compare, and the one most often quoted out of context.
- Pulse magnetizer
- Capacitor-discharge equipment that dumps a huge current through a fixture to magnetize or pattern a magnet.
R
- Remanence (Br)
- The flux density a magnet retains on its own - effectively how strong the magnet is.
- Reversible temperature coefficients & maximum operating temperature
- Br falls roughly 0.1% per degree C and Hci falls far faster in NdFeB; these are the alpha and beta coefficients on a datasheet. They recover on cooling, which is why maximum operating temperature - which depends on the grade AND the load line - is a far lower and far more useful number than Curie temperature.
- RoHS, REACH & critical-minerals controls
- Magnets carry the usual RoHS and REACH substance declarations, but rare earths now also sit on the US and EU critical-minerals lists, and both magnet materials and magnet-making technology are subject to export licensing. Provenance paperwork has become part of the quote, not an afterthought.
- Roll-up / consolidation
- Acquiring several small players in a fragmented market and unifying them into one operation.
S
- Shear force vs pull force
- Catalogue pull force is measured straight-on, on thick clean ground steel, in perfect contact. Slide the joint sideways and the usable shear value is a fraction of it; paint, plating, an air gap, thin or curved steel, and temperature all derate it further. Designing to catalogue pull force is the most common magnet-selection mistake.
- Sintered vs bonded
- Sintered magnets are pressed and fired for maximum strength; bonded magnets are moulded with a polymer, allowing complex multipole shapes at lower strength.
- SmCo (samarium cobalt)
- Weaker than NdFeB but far more heat- and corrosion-resistant; chosen for aerospace, defense and high-temperature use.
- Strip casting
- Rapidly solidifying molten rare-earth alloy into thin strip - the standard first step in making sintered NdFeB.
T
- Temperature grades (M, H, SH, UH, EH, AH)
- The letter suffix after an N-grade rates intrinsic coercivity, not strength: N (no suffix) is the standard room-temperature grade, and M, H, SH, UH, EH and AH step up heat resistance. Higher suffixes historically meant more dysprosium or terbium, so the suffix is also a cost and supply-risk signal.
U
- UN3506 & shipping magnetized material
- Magnetized material is a regulated air cargo hazard because it can deflect aircraft instrumentation. Packages must be shielded and measured so the field stays under the limit at the required distance from the package surface, and declared or certified as non-restricted accordingly - a real cost and lead-time factor on magnet freight.
What people actually ask us
These are not answered here, deliberately. A short answer to any of them would be wrong more often than it was right, because the honest answer depends on your situation.
- What is a coded magnet?
- What is a Polymagnet?
- What does the N number in a magnet grade mean?
- What is the strongest magnet you can buy?
- Are neodymium magnets the same thing as rare earth magnets?
- What's the difference between neodymium, samarium cobalt and ferrite magnets?
- What are the disadvantages of neodymium magnets?
- Is there a shortage of rare earth magnets and why are prices moving?
- What is a Halbach array and what is it good for?
- How can I see the poles on a magnet?
Also in this family: polymagnetics.com, multipolemag.com