Whether you’re unsure what Gauss is, or think the North Pole is only a geographic location, Magnetshub is happy to provide the necessary definitions and terminology to get you started. Still have questions, or think we missed something?
The space or distance between a magnet or magnetically receptive surface. It may consist of air, but can be created by other materials such as styrene, cardboard or a non-ferrous metal like aluminum.
Magnets made primarily with aluminum, nickel, cobalt, copper, iron and occasionally titanium. Alnico magnets can be cast or sintered, and are very temperature stable, however the material is very hard and brittle, not naturally lending itself to conventional machining.
An anisotropic material has different properties in different directions. For example, wood which has a grain is stronger in some one direction than another. Like wood, neodymium magnets are also anisotropic. Even before it is magnetized, a neodymium magnet has a “preferred” magnetization direction. See our article All About Magnetization Direction for more info.
Neodymium magnets are made with a preferred magnetization direction which can not be changed. These materials are either manufactured in the influence of strong magnetic fields or pressed a specific way, and can only be magnetized through the preferred axis.Sintered Neodymium (Iron Boron) and Samarium Cobalt magnets are anisotropic.
The result of plotting the value of the magnetic field (H) that is applied against the resultant flux density (B) achieved. This curve describes the qualities of any magnetic material.
The Maximum Energy Product at the point on the B/H Curve that has the most strength, expressed in MGOe (MegaGaussOersteds). When describing the grade of a neodymium magnet, this number is commonly referred to as the “N” number, as in Grade N52 magnets.
Also called “Residual Flux Density”. The magnetic induction remaining in a saturated magnetic material after the magnetizing field has been removed. This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material. By definition, this point occurs at zero air gap, and therefore cannot be seen in practical use of magnet materials.
The demagnetizing force, measured in Oersteds, necessary to reduce observed induction, B, to zero after the magnet has previously been brought to saturation.
The temperature at which a magnet loses all of its magnetic properties.
A force, which is the opposite direction of the field of a magnet, which removes the flux of a magnet after it has been fully magnetized.
a quantity that describes the torque a given magnet will experience in an external magnetic field.
Some folks (like physicists) use a magnetic dipole model to simulate or mathematically model a magnet or group of magnets. Mathematically, it’s easier than considering the complexities of weird magnet shapes. It’s not theoretically perfect. Using it won’t always match measured field strengths near a neodymium magnet. It works great for a sphere, but isn’t correct near other shapes like discs or blocks. It’s a great approximation when you’re measuring far away from a magnet, but not so good close up, especially near the edges of a magnet.
Calculate the dipole moment using the formula m = dipole moment in A m2 = Br x V / μo, where:
- Br is Br max, the Residual Flux Density, expressed in Tesla.
- V is the volume of the magnet, expressed in cubic meters.
- μo is the permeability of a vacuum, or 4 π x 10-7 N/A2.
A magnet consisting of a solenoid with an iron core, which has a magnetic field only during the time of current flow through the solenoid
A material that either is a source of magnetic flux or a conductor of magnetic flux. Most ferromagnetic materials have some component of iron, nickel, or cobalt.
Unit of magnetic induction, B. Lines of magnetic flux per square centimeter in the C.G.S. system of measurement. Equivalent to lines per square inch in the English system, and webers per square meter or tesla in the S.I. system. 10,000 gauss equals 1 tesla.
An instrument used to measure the instantaneous value of magnetic induction, B, usually measured in Gauss (C.G.S.). Also called a DC magnetometer.
The unit of magnetomotive force, F, in the C.G.S. system.
The magnetic flux per unit area of a section normal to the direction of flux. Measured in Gauss, in the C.G.S. system of units.
Indicates a materials’ resistance to demagnetization. It is equal to the demagnetizing force which reduces the intrinsic induction, Bi, in the material to zero after magnetizing to saturation; measured in oersteds.
Partial demagnetization of the magnet, caused by exposure to high or low temperatures, external fields, shock, vibration, or other factors. These losses are only recoverable by remagnetization. Magnets can be stabilized against irreversible losses by partial demagnetization induced by temperature cycles or by external magnetic fields.
A material that can be magnetized along any axis or direction (a magnetically unoriented material). The opposite of Anisotropic Magnet.
A soft iron piece temporarily added between the poles of a magnetic circuit to protect it from demagnetizing influences. Also called a shunt. Keepers are generally not needed for Neodymium and other modern magnets.
1 Kilogauss = 1,000 Gauss = Maxwells per square centimeter.
A magnet is an object made of certain materials which create a magnetic field. Every magnet has at least one north pole and one south pole. By convention, we say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet. This is an example of a magnetic dipole (“di” means two, thus two poles).
If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. If you take one of those pieces and break it into two, each of the smaller pieces will have a North pole and a South pole. No matter how small the pieces of the magnet become, each piece will have a North pole and a South pole. It has not been shown to be possible to end up with a single North pole or a single South pole which is a monopole (“mono” means one or single, thus one pole).
Consists of all elements, including air gaps and non-magnetic materials that the magnetic flux from a magnet travels on, starting from the north pole of the magnet to the south pole.
When specified on Magnetshub, the surface field or magnetic field refers to the strength in Gauss. For axially magnetized discs and cylinders, it is specified on the surface of the magnet, along the center axis of magnetization. For blocks, it is specified on the surface of the magnet, also along the center axis of magnetization. For rings, you may see two values. By,center specifies the vertical component of the magnetic field in the air at the center of the ring. By,ring specifies the vertical component of the magnetic field on the surface of the magnet, mid-way between the inner and outer diameters.
Magnetizing or demagnetizing force, is the measure of the vector magnetic quantity that determines the ability of an electric current, or a magnetic body, to induce a magnetic field at a given point; measured in Oersteds.
Is a contrived but measurable concept that has evolved in an attempt to describe the “flow” of a magnetic field. When the magnetic induction, B, is uniformly distributed and is normal to the area, A, the flux, Φ = BA.
Lines of flux per unit area, usually measured in Gauss (C.G.S.). One line of flux per square centimeter is one Maxwell.
The magnetic field induced by a field strength, H, at a given point. It is the vector sum, at each point within the substance, of the magnetic field strength and the resultant intrinsic induction. Magnetic induction is the flux per unit area normal to the direction of the magnetic path.
An imaginary line in a magnetic field, which, at every point, has the direction of the magnetic flux at that point.
An area where the lines of flux are concentrated.
The magnetic potential difference between any two points. Analogous to voltage in electrical circuits. That which tends to produce a magnetic field. Commonly produced by a current flowing through a coil of wire. Measured in Gilberts (C.G.S.) or Ampere Turns (S.I.).
Neodymium (NdFeB) magnets are graded by the magnetic material from which they are manufactured. Generally speaking, the higher the grade of material, the stronger the magnet. We find that the Pull Force of a magnet relates directly to the “N” number. Neodymium magnets currently range in grade from N35 to N52. The theoretical limit for Neodymium magnets is grade N64, though it isn’t currently feasible to manufacture magnets this strong. The grade of most of our stock magnets is N42 because we feel that N42 provides the optimal balance between strength and cost. We also stock a wide range of sizes in grade N52 for customers who need the strongest permanent magnets available.
The magnetic field strength at the point of maximum energy product of a magnetic material. The field strength of fully saturated magnetic material measured in Mega Gauss Oersteds, MGOe.
Also known as maximum service temperature, is the temperature at which the magnet may be exposed to continuously with no significant long-range instability or structural changes.
Unit of magnetic flux in the C.G.S. electromagnetic system. One maxwell is one line of magnetic flux.
The first quadrant portion of the hysteresis loop (B/H) Curve for a magnetic material.
The magnetomotive force per unit of magnet length, measured in Oersteds (C.G.S.) or ampere-turns per meter (S.I). Maxwell – The C.G.S. unit for total magnetic flux, measured in flux lines per square centimeter.
Mega (million) Gauss Oersteds. Unit of measure typically used in stating the maximum energy product for a given material. See Maximum Energy Product.
The north pole of a magnet is the one attracted to the magnetic north pole of the earth. This north-seeking pole is identified by the letter N. By accepted convention, the lines of flux travel from the north pole to the south pole.
The C.G.S. unit for magnetizing force. The English system equivalent is Ampere Turns per Inch (1 Oersted equals 79.58 A/m). The S.I. unit is Ampere Turns per Meter.
Used to describe the direction of magnetization of a material. Orientation Direction – The direction in which an anisotropic magnet should be magnetized in order to achieve optimum magnetic properties.
Materials that are not attracted to magnetic fields (wood, plastic, aluminum, etc.). A material having a permeability slightly greater than 1.
A magnet that retains its magnetism after it is removed from a magnetic field. A permanent magnet is “always on”. Neodymium magnets are permanent magnets.
Also known as pull strength or Max Force, pull force is the minimum required force to separate a magnet from a ferrous, metal surface to which it has attracted. Holding power of a magnet is determined by measuring pull force. Master Magnetics traditionally tests pull force on magnetic assemblies only.
Commonly used to describe high energy magnet material such as NdFeB (Neodymium-Iron-Boron) and SmCo (Samarium-Cobalt).
Flux density, measured in gauss, of a magnetic material after being fully magnetized in a closed circuit.
A second type of rare earth magnet, it is composed of samarium, cobalt and iron. Samarium cobalt magnets have high resistance to demagnetization, good temperature stability and are high-energy.
The magnetic pole which attracts to the geographic North pole where flux from the north pole terminates.
The S.I. unit for total magnetic flux. The practical unit of magnetic flux. It is the amount of magnetic flux which, when linked at a uniform rate with a single-turn electric circuit during an interval of 1 second, will induce in this circuit an electromotive force of 1 volt.