Technichal Magnet Data


To help our customers learn more about our flexible magnet, hard magnets, and pressure sensitive adhesive tape products, we have created these downloadable brochures for your reference. These downloadable brochures are just a summary of key information to help you select the right magnet or adhesive solution for your product.

By printing these brochures and discussing potential solutions with your team, we can then fill in the rest of the information you need to solve your magnetic challenges.

As always, call us for assistance in selecting the right magnet or adhesive product for your specific needs.

Below are key brochures available for download:


Rochester Magnet Capabilities Overview

Flexible Magnet Capabilities

Packaging Solutions

Sign Solutions Brochure


Adhesive Tape Products

Adhesive Tape Reference Guide


Below is a wide range of information about magnets – some specific to the products we offer and most information generic to all magnets. Flexible and hard magnets can be a simple concept as north and south polarity and as complex as magnets in aeronautics or an MRI machine. From a refrigerator magnet to a magnet that helps to trip a switch, the information provided will help provide a more in-depth background. By clicking on the headings below, you can learn more about each specific topic related to magnets.

The team at Rochester Magnet is always here to help you find the information you need to assist you with your magnetic solution. If you do not see what you are looking for, please feel free to Contact Us. We are happy to help in anyway we can.

An object that creates a magnetic field is a magnet, and a magnetic field is characterized as an energy field that attracts ferrous compounds and attracts or repels other magnets.

The movement of electrons creates energy, so when a number of electrons are in alignment in terms of their direction, they create sufficient energy to attract other objects with opposite yet similarly aligned electron movements. The directional nature of the movement is responsible for the opposite attraction forces generally called “Poles” and identified as “North” and “South”.

In the simplest terms, opposites attract and likes repel. North and south attract each other to combine and make a solid connection. It is impossible for north on north or south on south to attract and connect. These forces repelling help to make products such as Maglev trains.

A list of magnet materials is provided in the overview below. This summary desribes flexible magnets, ceramic magnets, rare earth magnets, AlNiCo Magnets, and a wide variety of other magnetic materials. They are in the form of solid shapes (discs, spheres, or blocks), as well as channel and sandwich assemblies. Each one of these magnets have a unique set of characteristics and applications pertinent to strength, temperature ranges, size, and hardness. From refrigerator magnets, sign magnets, printable magnets, or packaging magnets, we have the stock available to help solve your magnetic needs.

A list of magnet materials is provided below – each has a unique set of characteristics and applications.

MaterialResidual Flux Density Br (Gauss)Maximum Coercive Force Hc (Oersteds)Energy Product BHmax (MGOe)Slope of Load Line at BHmaxCurie Point (°C)Maximum Practical Operating Temp. (°C / °F)Temp. Coefficient (% Loss / °C)Relative Density (Lbs. / Cubic Inch)
Sintered AlNiCo II7,1005601.512.3840540 / 10000.0150.247
Cast AlNiCo V12,8006405.518890540 / 10000.0130.264
Sintered AlNiCo V10,9006203.9518.4860540 / 10000.0070.253
Cast AlNiCo VIII8,2001,6505.35870540 / 10000.0130.265
Sintered AlNiCo VIII7,4001,50045840540 / 10000.0070.253
SmCo 188,5008,000181700260 / 500.030 – .0450.3
SmCo 229,5008,600221825260 / 500.015 – .0300.3
SmCo 2610,5009,200261825350 / 660.015 – .0300.3
NdFeB 2710,80010,00027130080 / 1760.120.267
NdFeB 30H11,60011,000301300120 / 2480.120.267
NdFeB 3512,20011,80035130080 / 1760.130.267
Ceramic I2,3001,86011.2460400 / 7500.1290.167
Ceramic V3,8002,4003.41.1460400 / 7500.190.18
Ceramic VIII3,8502,9503.51460400 / 7500.190.18
Flexible Regular1,6001,3700.61.2*70 / 1600.190.133
Flexible High Force2,2001,9001.11.2*70 / 1600.190.14

* Standard Flexible Magnets contain bonding agents that may cause the loss of magnetization at temperatures above 1600F (700 C)

Reference materials, websites and other sources are provided here to help you understand and apply magnets. We welcome requests/recommendations for additional materials – simply click on the “Contact Us” button and send us an e-mail.

Magnetic Material Producers Association Standard Specifications for Permanent Magnet Materials

Defines thermal and mechanical characteristics and properties of commercially available permanent magnet materials including AlNiCo, Ceramic, Rare Earth (Samarium Cobalt and Neodymium) and Iron-Chromium-Cobalt. Includes a Glossary of Terms and Magnetic Quantities (Symbols, Units and Conversion Factors).

MMPA – Standard Spec for Permanent Magnetic Material.pdf

Air Gap – The distance between the magnet and another attractive surface – i.e. another magnet or ferrous material. This gap is referred to as “Air Gap” regardless of whether the distance is filled with air or another non-magnetic material.Anisotropic – A “preferred” magnetization direction characterizes materials referred to as Anisotropic. Generally, the materials are manufactured using a strong magnetic field, and can only be magnetized through the preferred axis. Neodymium (Iron Boron) and Samarium Cobalt magnets are examples of anisotropic magnets.

B/H Curve – The result of plotting the value of the magnetic field (H) that is applied against the resultant flux density (B), the resultant plot characterizes the magnetic material. BHmax (Maximum Energy Product) – 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).

Brmax (Residual Induction) – Also called “Residual Flux Density”. It is 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. This point occurs, by definition, at zero air gap, and therefore is useful as a comparative tool rather than an absolute measurement.

C.G.S. – An abbreviation for the “Centimeter, Grams, Second” system of measurement.

Coercive Force – The demagnetizing force, measured in Oersteds, necessary to reduce observed induction, B, to zero after the magnet has previously been brought to saturation.

Curie Temperature (Tc) – The temperature at which a magnet loses magnetic properties.

Demagnetization Curve – The second quadrant of the hysteresis loop, generally describing the behavior of magnetic characteristics in actual use. Also known as the B/H Curve.

Demagnetization Force – A magnetizing force, typically in the direction opposite to the force used to magnetize it in the first place. Shock, vibration and temperature can also be demagnetizing forces.

Dimensional Tolerance – An allowance, given as a permissible range, in the nominal dimensions of a finished magnet. The purpose of a tolerance is to specify the physical parameters for applications where the magnet has an interface with other components. Electromagnet – A magnet consisting of a solenoid with an iron core, which has a magnetic field only when current is flowing through the solenoid.

Ferromagnetic Material – A material that either is a source of magnetic flux or a conductor of magnetic flux. Any ferromagnetic material must have some component of iron, nickel, or cobalt.

Gauss – 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.

Gauss meter – An instrument used to measure the instantaneous value of magnetic induction, (B) usually measured in Gauss (C.G.S.).

Gilbert – The unit of magnetomotive force, F, in the C.G.S. system.

Hysteresis Loop – A plot of magnetizing force versus resultant magnetization (also called a B/H curve) of the material as it is successively magnetized to saturation, demagnetized, magnetized in the opposite direction and finally remagnetized. With continued recycles, this plot will be a closed loop which completely describes the characteristics of the magnetic material. The size and shape of this “loop” is important for both hard and soft materials. With soft materials, which are generally used in alternating circuits, the area inside this “loop” should be as thin as possible (it is a measure of energy loss). But with hard materials the “fatter” the loop, the stronger the magnet will be. The first quadrant of the loop (that is +X and +Y) is called the magnetization curve. It is of interest because it shows how much magnetizing force must be applied to saturate a magnet. The second quadrant (+X and -Y) is called the Demagnetization Curve.

Induction (B) – 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.

Intrinsic Coercive Force (Hci) – Indicates a material’s resistance to demagnetization. This is equal to the demagnetizing force which reduces the intrinsic induction, Bi, in the material to zero after magnetizing to saturation; measured in Oersteds.

Irreversible Losses – 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. Isotropic Material – A material that can be magnetized along any axis or direction – the opposite of Anisotropic Magnet.

Keeper – A soft iron piece temporarily added between the poles of a magnetic circuit to protect it from demagnetizing influences. Kilogauss – One Kilogauss = 1,000 Gauss = Maxwells per square centimeter.

Magnet – 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).

Magnetic Circuit – 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.

Magnetic Field (B) –

When specified on our site, 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, midway between the inner and outer diameters.

Magnetic Field Strength (H) – 
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.

Magnetic Flux – A 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, Ø = BA.

Magnetic Flux Density – Lines of flux per unit area, usually measured in Gauss (C.G.S.). One line of flux per square centimeter is one Maxwell.

Magnetic Induction (B) – 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.

Magnetic Line of Force – An imaginary line in a magnetic field, which, at every point, has the direction of the magnetic flux at that point.

Magnetic Pole – An area where the lines of flux are concentrated.

Magnetomotive Force (F or mmf) – 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.).

Material Grade – Several magnet materials are constructed in different “Grades” which represent the material characteristics. Generally, the higher number for the Grade, the higher the magnetic holding power. Maximum Energy Product (BHmax) – 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.

Maximum Operating Temperature (Tmax) – The maximum service temperature, i.e. the temperature at which the magnet may be exposed to continuously with no significant long-range instability or structural changes.

Maxwell – Unit of magnetic flux in the C.G.S. electromagnetic system. One Maxwell is one line of magnetic flux.

Magnetization Curve – The first quadrant portion of the hysteresis loop (B/H) curve for a magnetic material.

Magnetizing Force (H) – 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.

MGOe – Mega (million) Gauss Oersteds. Unit of measure typically used in stating the maximum energy product for a given material. See Maximum Energy Product.

North Pole – 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.

Oersted (Oe) – 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.

Orientation – 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.

Paramagnetic Materials – Materials that are not attracted to magnetic fields (wood, plastic, aluminum, etc.). A material having a permeability slightly greater than 1.

Permanent Magnet – 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.

Permeance (P) – A measure of relative ease with which flux passes through a given material or space. It is calculated by dividing magnetic flux by magnetomotive force. Permeance is the reciprocal of reluctance.

Permeance Coefficient (Pc) – Also called the load-line, B/H or “operating slope” of a magnet, this is the line on the Demagnetization Curve where a given magnet operates. The value depends on both the shape of the magnet, and it’s surrounding environment (some would say, how it’s used in a circuit). In practical terms, it’s a number that defines how hard it is for the field lines to go from the north pole to the south pole of a magnet. A tall cylindrical magnet will have a high Pc, while a short, thin disc will have a low Pc.

Permeability (µ) – The ratio of the magnetic induction of a material to the magnetizing force producing it (B/H). The magnetic permeability of a vacuum (µo) is 4π×10-7 N/Amp2.

Pole – An area where the lines of magnetic flux are concentrated.

Plating/Coating – Most neodymium magnets are plated or coated in order to protect the magnet material from corrosion. Neodymium magnets are mostly composed of neodymium, iron, and boron. The iron in the magnet will rust if it is not sealed from the environment by some sort of plating or coating. Most of the neodymium magnets that we stock are triple plated in nickel-copper-nickel, but some are plated in gold, silver, or black nickel, while others are coated in epoxy, plastic or rubber.

Polarity – The characteristic of a particular pole at a particular location of a permanent magnet. Differentiates the North from the South Pole.

Pull Force – The force required to pull a magnet free from a flat steel plate using force perpendicular to the surface. The limit of the holding power of a magnet. The pull force listed is actual data acquired by testing using our state-of-the-art force test stand. A comprehensive table of the pull force for all of our stock magnets is available here: Pull Force Table.
We test for two different values of pull force using two different setups. Read more about these two pull forces here.

Rare Earth – Commonly used to describe high energy magnet material such as NdFeB (Neodymium-Iron-Boron) and SmCo (Samarium-Cobalt).

Relative Permeability – The ratio of permeability of a medium to that of a vacuum. In the C.G.S. system, the permeability is equal to 1 in a vacuum by definition. The permeability of air is also for all practical purposes equal to 1 in the C.G.S. system.

Reluctance (R)- A measure of the relative resistance of a material to the passage of flux. It is calculated by dividing magnetomotive force by magnetic flux. Reluctance is the reciprocal of permeance.

Remanence, (Bd) – The magnetic induction that remains in a magnetic circuit after the removal of an applied magnetizing force.

Residual Flux Density (Brmax) – Also called “Residual Induction”. It is 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.

Residual Induction (Brmax) – Also called “Residual Flux Density”. It is 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.

Return Path – Conduction elements in a magnetic circuit which provide a low reluctance path for the magnetic flux. Reversible Temperature Coefficient: A measure of the reversible changes in flux caused by temperature variations.

Saturation – The state where an increase in magnetizing force produces no further increase in magnetic induction in a magnetic material.

Shunt – A soft iron piece temporarily added between the pole of a magnetic circuit to protect it from demagnetizing influences. Also called a keeper. Not needed for Neodymium and other modern magnets.

S.I. – Abbreviation for “Système International”. Refers to the International Standard System of units. It is also known as the MKS system.

South Pole – The south pole of a magnet is the one attracted to the south pole of the earth. This south-seeking pole is identified by the letter S. By accepted convention, the lines of flux travel from the north pole to the south pole.

Stabilization – The process of exposing a magnet or a magnetic assembly to elevated temperatures or external magnetic fields to demagnetize it to a predetermined level. Once done the magnet will suffer no future degradation when exposed to that level of demagnetizing influence.

Surface Field (Surface Gauss) – The magnetic field strength at the surface of the magnet as measured by a Gauss meter. A comprehensive table of the surface field for all of our stock magnets is available here: Surface Field Table.

Temperature Coefficient – A factor that is used to calculate the decrease in magnetic flux corresponding to an increase in operating temperature. The loss in magnetic flux is recovered when the operating temperature is decreased.

Tesla – The S.I. unit for magnetic induction (flux density). One Tesla equals 10,000 Gauss.

Weber – 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.

Storing Flexible Magnet

  • When not using flexible magnetic sheet, keep it in a clean, dry place.
  • Store rolled stock on end to keep it from developing flat spots.
  • Store rolled sign material on end with the printed or vinyl side out. 
  • Stack sheet magnet on a level surface. Avoid placing objects (such as cartons) on top of sheets that could damage the face; do not stack with magnetic sides facing each other.

Preparing Surfaces for Sheet Magnets

Uncured surface treatments are very easy to scratch and/or stain so, before affixing magnetic sheet to a metal surface, be sure all surface paints, clear coats and waxes are cured (hardened).*

  • Clean the metallic surface and the magnet with mild detergent. 
  • Wipe with a soft cloth or allow to dry.

*(Approximate curing times:  paint—90 days; clear coat—60 days; wax—2 days.)

Applying Flexible Magnets

Before applying, test all inks and paints used on the magnet for adhesion and solvent compatibility.

  • Affix to smooth, flat or gently curved metallic surfaces. 
  • Make sure the entire magnet is flat against the metal surface. Do not place over protrusions (molding, decals, pin striping, etc.) or concave areas. There must be NO air pockets – the ability of the magnet to stay attached to the surface is dramitically reduced with air pockets. 
  • The magnet itself should be at a temperature of 60°F (16°C) or above when installed to achieve best results. 
  • Do not apply magnet that has been curled with the magnet side out. The magnet may not attach properly to the metallic surface resulting in lifted corners or air gaps which will weaken its holding strength. The instructions for storing Flexible Magnet provides tips on how to avoid having the material curl in the wrong direction.
  • If you place the magnet in the wrong position, completely remove the magnet from the surface and reaffix. Lift at sides and not at corners to remove. Do not pull the magnet across the surface, or it may stretch due to the resistance caused by the high magnetic strength. 
  • Do NOT use on horizontal metal surfaces exposed to direct sunlight (such as automobile hoods), temperatures exceeding 160ºF (71ºC) or temperatures below -15ºF (-26ºC). Exposure to cold weather will make the magnet more brittle so use caution when handling.
  • Be aware that long-term use on surfaces frequently exposed to sunlight (such as vehicles) can result in uneven fading of the surface because the magnet-covered area is shielded from ultraviolet rays.
  • Do NOT use on non-metallic body fillers, simulated wood grain siding and repainted surfaces. NOTE: Doors and panels on some vehicles are not made of steel. This product will not work on aluminum and plastic surfaces.  
  • We recommend rounded corners for magnetic vehicle signage.

Cleaning Flexible Magnet

  • To guard against moisture and dirt buildup between the magnet and the metal surface (particularly on outdoor applications), remove the magnet at regular intervals. Clean both the magnet and metal surface with mild detergent; wipe with a soft cloth or allow to air-dry. (For vehicle-mounted signs, remove and clean DAILY.)
  • After waxing and polishing, allow 2 days for wax to cure before applying the Flexible Magnet. Remember – you can always call us and ask our advice and assistance.