Magnet Glossary

A

• Air GapAn air gap is a nonmagnetic material between a magnet and an attracted object, or between two magnets attract…
• AnisotropicA magnet is called anisotropic when all of its magnetic domains are aligned in the same direction during manu…
• AxialThe term axially magnetized describes a magnet that is magnetized between two flat, parallel faces.

B

• B-H CurveThe B-H curve is a graph showing the relationship between magnetic flux density (B) and magnetic field streng…
• Bar MagnetA bar magnet is a permanent magnet with a magnetic length greater than its diameter, with a north and south p…
• Blocking a Magnetic FieldOnly materials that are attracted to a magnet can "block" a magnetic field, partially or completely depending…

C

• Changing Magnet StrengthOnce a magnet is fully magnetized, it is "saturated" and cannot be made any stronger.
• Closed CircuitA closed magnetic circuit is an arrangement of magnetic and ferrous material that connects the north pole of …
• Coercive ForceCoercive force is the intensity required to reduce the magnetization of a saturated object to zero, measuring…
• CoercivityCoercivity is a measure of how permanent a magnet is, or how much magnetic force is needed to reverse its mag…
• Curie TemperatureThe Curie temperature is the point at which materials lose their ferromagnetism and become paramagnetic.

D

• DemagnetizationDemagnetization is the reduction or removal of magnetization in a ferromagnetic body, such as iron parts of a…
• DensityDensity is a measure of a material's mass per unit volume. Knowing a magnet's density lets you calculate its …
• DiamagneticDiamagnetism is a type of magnetism that aligns at right angles to an object's magnetic field and therefore h…
• DiamagnetismDiamagnetism is the ability of a material to create an opposing magnetic field when exposed to a strong magne…
• DiameterThe diameter applies to round magnets and is the distance measured across a flat, round surface through its e…
• DiametricCylindrical magnets are called diametrically magnetized when their direction of magnetization runs parallel t…
• Dimensional ToleranceMagnets are produced in batches, and during machining the tolerance determines the maximum and minimum permit…
• DimensionsThe finished size of a magnet, including all surface treatments such as coatings and platings.

E

• Earth's Magnetic FieldThe Earth's surface field strength is about 0.5 gauss but varies by up to 10% depending on the strength of th…
• Eddy CurrentsEddy currents are electric currents induced when a magnetic field moves relative to an electrical conductor w…
• ElectromagnetAn electromagnet works on the principle that an electric current not only moves electrons through a circuit b…
• ElectromagnetsElectromagnets are used when very strong magnets are needed. They consist of a metal core inside a coil of wi…

F

• FerromagnetismFerromagnetism is the property of a material whose magnetic moments align parallel to each other in the prese…
• Field StrengthFor a round magnet with radius R and length L, the field Bx on the centerline at distance X from the surface …
• Flux DensityFlux density describes the number of lines of magnetization per square centimeter of pole area and is measure…

G

• GaussNamed after the mathematician Carl Friedrich Gauss, the gauss is a unit used to measure magnetic fields.
• GilbertThe gilbert is a unit of magnetomotive force, named after the English scientist and physician William Gilbert.
• GradeEach type of magnet is made in different grades. The grade defines the chemical and magnetic properties of th…

H

• HistoryThe ancient Greeks and Chinese discovered that certain rare stones, called lodestones, were naturally magneti…
• Homogeneous FieldA homogeneous magnetic field is one in which the field lines are uniform and produce an equal force at every …
• Horseshoe MagnetThe best known magnet, the horseshoe magnet, is a permanent magnet usually made of alnico, with a north pole …
• Hysteresis LoopA hysteresis loop is a four quadrant graph showing magnetizing force relative to the resulting magnetization …

I

• InductionMagnetic induction, also called flux density, is the number of lines of magnetism in each square centimeter o…
• Industry StandardsYes, industry standards for magnets were set by the MMPA and the MDFA, both now part of the International Mag…
• Influencing FactorsWhat can affect the strength of a magnet? Key factors include heat, radiation, strong electric currents and o…
• Intrinsic Coercivity (Hci)Intrinsic coercivity is the force required to permanently demagnetize a magnet. It is measured in kilo-oerste…
• Irreversible LossesIrreversible losses are the percentage of magnetism a magnet loses permanently in extreme situations, such as…
• IsotropicA magnet made of magnetically isotropic material has no preferred direction and has the same properties along…

K

• KeeperA keeper is a steel bar or plate placed across the opposite poles of a magnet so that all the magnetism can f…

L

• Loss of StrengthModern magnet materials lose a very small part of their magnetism over time, for samarium cobalt less than 1%…

M

• Magnet AssemblyA magnet assembly consists of one or more magnets combined with other components, such as steel, that usually…
• Magnet FunctionMagnets attract certain materials, exert force on other magnets and affect conductors and charged particles, …
• Magnet InformationHow can you use magnet information? Magnet data lets you estimate how much magnetic flux different materials …
• Magnet LifespanWhen kept away from factors that affect it, such as power lines, other magnets or high temperatures, a magnet…
• Magnet MachiningMagnets can be machined, but hard magnetic materials are extremely difficult to work, unlike flexible or rubb…
• Magnet Machining CostsThe cost of machining magnets depends mainly on quantity, material, shape and the required tolerances.
• Magnet ManufacturingModern magnet materials are made by casting, pressing and sintering, compression bonding, injection molding, …
• Magnet PolesMagnet poles are the surfaces from which the invisible lines of magnetic flux emerge and connect when returni…
• Magnet RatingsMagnets are characterized by three main properties: residual induction, coercive force and maximum energy pro…
• Magnet StrengthGaussmeters, magnetometers and pull testers are the most common tools for measuring a magnet's strength.
• Magnet TypesThere are three types of magnets: permanent magnets, temporary magnets and electromagnets.
• Magnetic AxisIn an anisotropic magnet, all magnetic domains are aligned the same way. The line of direction they follow is…
• Magnetic CircuitAll magnetism flows from north to south, and a magnetic circuit is the path it takes to get from north to sou…
• Magnetic DomainMagnetic materials such as permanent magnets are divided into microscopic regions called domains, each with a…
• Magnetic FieldsThe space around a magnet in which a magnetic force acts is called a magnetic field.
• Magnetic PoleThe ends of a magnet are called poles: one is the north pole and the other the south pole.
• Magnetic RegionsMagnetic materials such as permanent magnets are divided into individual microscopic regions whose structure …
• MagnetismMagnetism describes the forces of repulsion and attraction between different substances, such as iron and oth…
• Magnetization DirectionMagnets can be magnetized across any axis. The direction of magnetism determines which side of the magnet is …
• MagnetsMagnets can be made by placing a magnetic material, such as iron or steel, in a strong magnetic field.
• Maximum Energy Product (BHmax)The maximum energy product of a magnet is measured in mega gauss oersteds (MGOe) and is the primary indicator…
• Maximum TemperatureMagnets work with different efficiencies depending on the circuits in which they operate.
• Measuring the Surface FieldIf a neo magnet has a Br of 12,300 gauss, you will not measure 12,300 gauss on its surface, because Br is mea…
• MGOeMega gauss oersteds is the CGS measure of a magnet's maximum energy product (BHmax).
• MountingWhen a magnet needs to be attached to a device, you can use either mechanical means or adhesives to hold it i…

N

• North and South PoleThe north pole is defined as the pole of a magnet that, when free to rotate, seeks the Earth's north pole.
• North PoleYou cannot tell the north pole just by looking. Place a compass near the magnet to find out.

O

• Operating TemperaturesWhat are the maximum recommended operating temperatures for different magnet materials? An overview for NdFeB…
• OrderingTo order magnets efficiently, you need a clear idea of what you want to achieve. Here are the key points to c…
• Orientation DirectionMost modern magnet materials have a "grain" and can only be magnetized in one direction for maximum effect: t…

P

• ParamagnetismParamagnetism was first studied and discovered by British scientist Michael Faraday and occurs in materials w…
• Permanent MagnetA permanent magnet is a material that can produce a magnetic field and stays magnetized after the external fi…
• Permanent MagnetsModern permanent magnets are made from special alloys such as alnico, ferrite, neodymium iron boron and samar…
• PermeabilityThe ability of a material to become magnetized is called its magnetic permeability.
• PlatingPlating is another term for coating. Raw neodymium magnets are plated or coated to prevent corrosion and dema…
• PolesYes, the north or south pole of a magnet can be marked if required.
• Pull ForcePull force is one way of measuring a magnet's strength: the force needed to separate the magnet from a low ca…
• Pull Force FactorsA magnet's pull force is determined by its gauss rating and its geometry.
• Pull Force TestNot necessarily. The pull force test is a laboratory test carried out under ideal conditions.

R

• Rare Earth MagnetsRare earth magnets are made from the rare earth group of elements. The most common are neodymium iron boron a…
• RemagnetizedUnless the material has been damaged by extreme heat, most magnets can be remagnetized back to their original…
• RemanenceRemanence, or residual magnetism, is the magnetization that remains in a ferromagnetic material after an exte…

S

• StoragePractical tips for handling and storing magnets safely, from avoiding injuries to protecting alnico magnets w…
• Strongest MagnetsThe strongest magnets available today are rare earth magnets, and among them neodymium magnets are the strong…
• SuperconductorSuperconductors are the strongest magnets. They need no metal core and consist of wire coils made of special …

T

• Temporary MagnetSoft iron and certain iron alloys such as permalloy are magnetized very easily even in a weak field, but lose…
• TeslaThe tesla is an SI unit for measuring the strength of a magnetic field and is abbreviated with the symbol T i…
• TmaxThe maximum operating temperature is the highest temperature at which a given magnet type can operate before …