Global Elements Solutions
Global Elements Solutions
Air gap refers to the external distance between the two magnetic poles measured through a non-magnetic medium, typically air.
An anisotropic material exhibits different physical properties depending on the direction. Neodymium magnets are anisotropic because they have a fixed, preferred magnetization direction even before magnetization.
The B/H curve plots the applied magnetic field strength (H) against the resulting magnetic flux density (B). It characterizes the magnetic behavior and performance of a magnetic material.
BHmax is the maximum energy product of a magnetic material, defined as the point on the B/H curve where the product of magnetic flux density (B) and magnetic field strength (H) is the greatest. It is expressed in MGOe (MegaGauss-Oersteds).
Brmax, or residual flux density, is the magnetic induction remaining in a saturated magnetic material after the external magnetizing field is removed. It is the point where the hysteresis loop crosses the B-axis at zero magnetizing force.
C.G.S. is the abbreviation for the Centimeter–Gram–Second system of measurement.
Coercive force (Hc) is the demagnetizing force required to reduce the observed magnetic induction (B) to zero after the material has been fully saturated. It is measured in Oersteds (Oe) in the C.G.S. system.
Curie temperature is the temperature at which a magnetic material loses all of its magnetic properties.
The demagnetization curve is the second quadrant of the hysteresis loop, describing the magnetic behavior of a material under practical use conditions. It is also known as the B-H curve.
Demagnetization force is a magnetic force, usually applied opposite to the original magnetizing direction, which reduces the magnetization of a material. External factors such as shock, vibration, or high temperature can also act as demagnetizing forces.
Dimensions refer to the physical size of a magnet, including any plating or coating applied.
Dimensional tolerance is the permissible variation range in the nominal dimensions of a finished magnet, defining the allowed deviations in manufacturing.
An electromagnet is a magnet created by a solenoid with an iron core, which generates a magnetic field only when electric current flows through the coil.
A ferromagnetic material is one that can generate or conduct magnetic flux. Most ferromagnetic materials contain iron, nickel, or cobalt.
Gauss is a unit of magnetic induction (B), representing the number of magnetic flux lines per square centimeter in the C.G.S. system. 10,000 Gauss equals 1 Tesla in the S.I. system.
A Gauss meter is an instrument used to measure the instantaneous value of magnetic induction (B), typically in Gauss (C.G.S. units). It is also called a DC magnetometer.
A Gilbert is the unit of magnetomotive force (F) in the C.G.S. system.
A hysteresis loop is a plot of magnetizing force (H) versus resultant magnetization (B) as a material is successively magnetized to saturation, demagnetized, magnetized in the opposite direction, and remagnetized. The loop fully describes the magnetic characteristics of the material.
Induction (B) is the magnetic flux per unit area, measured in Gauss (C.G.S. units), and is typically perpendicular to the direction of the flux.
Intrinsic coercive force (Hci) is the demagnetizing force required to reduce the intrinsic magnetic induction (Bi) of a fully saturated material to zero. It is measured in Oersteds (Oe).
Irreversible losses are partial demagnetizations of a magnet caused by high or low temperatures, external magnetic fields, shock, vibration, or other factors. These losses can only be restored through remagnetization.
An isotropic material can be magnetized along any axis or direction. It is a magnetically unoriented material, the opposite of an anisotropic magnet.
A keeper is a soft iron piece placed temporarily across the poles of a magnet to protect it from demagnetizing influences, also called a shunt.
One Kilogauss = 1,000 Gauss = Maxwells per square centimeter.
A magnet is an object made of materials that creates a magnetic field. Every magnet has at least one north pole and one south pole, forming a magnetic dipole. Cutting a magnet into smaller pieces will result in each piece having both a north and a south pole; monopoles do not naturally occur.
A magnetic circuit consists of all elements, including air gaps and non-magnetic materials, through which magnetic flux travels, starting from the north pole of a magnet and ending at the south pole.
The magnetic field (B) represents the strength of a magnet, typically measured in Gauss (C.G.S. units). It describes the magnetic force produced by a magnet at different points and is a key parameter for evaluating magnet performance.
The field is often specified at the surface of the magnet or along its center axis, depending on the magnet’s shape:
Axially magnetized discs and cylinders: measured on the surface along the center axis of magnetization.
Block magnets: measured on the surface along the center axis of magnetization.
Ring magnets: may provide two values:
By, center: vertical component of the magnetic field in the air at the center of the ring.
By, ring: vertical component of the magnetic field on the surface of the magnet, midway between the inner and outer diameters.
Magnetic field strength (H) is the magnetizing or demagnetizing force that measures the vector magnetic quantity responsible for creating or influencing a magnetic field at a given point. It determines the ability of an electric current or a magnetic material to induce a magnetic field. Magnetic field strength is typically measured in Oersteds (Oe).
Magnetic flux (Φ) is a conceptual but measurable quantity used to describe the “flow” of a magnetic field through a given area. When the magnetic induction (B) is uniformly distributed and perpendicular to the area (A), the magnetic flux is calculated as:
Φ=B×A\Phi = B \times AΦ=B×Awhere Φ is the magnetic flux, B is the magnetic induction, and A is the area through which the flux passes.
Magnetic flux density is the 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) is the magnetic field produced at a point in a material due to an applied magnetic field strength (H). It represents the vector sum, at each point within the material, of the applied magnetic field and the resultant intrinsic induction. Magnetic induction is also defined as the magnetic flux per unit area perpendicular to the direction of the magnetic path.
Magnetic lines of force are imaginary lines that represent the direction of the magnetic flux at every point in a magnetic field. They illustrate the path along which the magnetic field exerts its influence and indicate the orientation of the magnetic forces.
Magnetic poles are an area where the lines of flux are concentrated.
Magnetomotive Force (MMF) is the magnetic potential difference between two points in a magnetic circuit. It drives the creation of a magnetic field, similar to how voltage drives current in an electrical circuit. MMF is typically generated by an electric current passing through a coil of wire.
The material grade of a Neodymium (NdFeB) magnet indicates the strength of the magnetic material used in its production. Higher grades correspond to stronger magnets. Grades are denoted by an “N” number, typically ranging from N35 to N52, with N64 representing the theoretical maximum (not currently manufacturable).
Most stock magnets are N42, offering a balance of strength and cost, while N52 magnets are available for applications requiring the highest magnetic performance.
Maximum Energy Product represents the maximum magnetic energy density a material can provide. It indicates the strength of a fully saturated magnet and is measured in Mega Gauss Oersteds (MGOe).
Maximum Operating Temperature, also called Maximum Service Temperature, is the highest temperature at which a magnet can operate continuously without significant loss of magnetic properties or structural degradation. Staying within this limit ensures long-term stability and performance of the magnet.
A maxwell is a unit of magnetic flux in the C.G.S. electromagnetic system. One Maxwell is one line of magnetic flux.
The magnetization curve is the first quadrant portion of the hysteresis loop (B/H) curve for a magnetic material.
Magnetizing force is the magnetomotive force per unit of magnet length, measured in Oersteds (C.G.S.) or ampere-turns per meter (S.I). and is the C.G.S. unit for total magnetic flux, measured in flux lines per square centimeter.
MGOe stands for mega (million) Gauss Oersteds and is the 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 end that is attracted to the Earth’s geographic North Pole, also called the north-seeking pole, and is marked with the letter N. By convention, magnetic field lines (flux) flow from the magnet’s north pole to its south pole.
An Oersted is 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.
Magnet orientation refers to the alignment of magnetic domains within a material during manufacturing. Proper orientation maximizes magnetic properties such as strength, energy product (BH<sub>max</sub>), and coercivity. Common methods include pressing and sintering, melt spinning, magnetic annealing, and extrusion or calendering for flexible materials. The chosen method depends on the material type and application, ensuring optimal performance and reliability in motors, generators, sensors, and data storage devices.
Orientation direction is the direction in which an anisotropic magnet should be magnetized in order to achieve optimum magnetic properties.
Paramagnetic materials exhibit weak magnetic properties only in the presence of an external magnetic field. Their magnetic behavior arises from unpaired electrons, whose magnetic moments align with the applied field, producing a temporary magnetization. Unlike ferromagnetic materials, paramagnetic materials do not retain significant magnetization once the external field is removed.
A permanent magnet is a magnet that retains its magnetism even after the external magnetic field is removed. It provides a continuous magnetic field, and neodymium (NdFeB) magnets are a common example of permanent magnets.
Permeance measures how easily magnetic flux can pass through a material or magnetic circuit. It indicates the material’s ability to conduct magnetic lines of force and is analogous to electrical conductance in electric circuits.
The permeance coefficient, also called the load-line, B/H, or operating slope, represents the line on a magnet’s demagnetization curve where it operates. It depends on the magnet’s shape and its surrounding environment, indicating how easily magnetic field lines travel from the north pole to the south pole. For example, a tall cylindrical magnet has a high Pc, while a short, thin disc has a low Pc.
Permeability is the ratio of a material’s magnetic induction (B) to the magnetizing force (H) that produces it, measuring how easily the material becomes magnetized in a magnetic field. The magnetic permeability of a vacuum (µ₀) is 4π × 10⁻⁷ N/A².
Most neodymium magnets are plated or coated to protect against corrosion, as the iron content can rust if exposed to the environment. Common plating includes nickel-copper-nickel, while some magnets are plated with gold, silver, or black nickel, or coated with epoxy, plastic, or rubber to enhance durability and resistance to environmental damage.
Magnetic polarity refers to the two ends of a magnet, the North Pole and South Pole, which exhibit opposite magnetic properties. Opposite poles attract while like poles repel. By convention, magnetic field lines flow from the North Pole to the South Pole outside the magnet. Magnetic poles always exist in pairs—cutting a magnet creates smaller magnets, each with its own North and South Poles. Understanding polarity is essential for applications ranging from motors and generators to magnetic levitation and data storage.
A pole is an area where lines of magnetic flux are concentrated.
Pull force is the force required to separate a magnet from a ferromagnetic material (e.g., iron or steel) when in full contact.
It indicates the magnet’s strength and how difficult it is to remove from the attracted material.
Factors affecting pull force:
Magnet size and shape: Larger and thicker magnets generally have higher pull force.
Magnet material: Materials with higher BH<sub>max</sub> produce stronger pull force (e.g., neodymium vs. ceramic).
Distance: Pull force decreases sharply as the distance between the magnet and the material increases.
Surface condition: Full direct contact maximizes pull force; air gaps, rough surfaces, or contaminants reduce it.
Thickness of ferromagnetic material: Sufficient thickness is needed to fully “absorb” the magnet’s field; too thin materials may saturate and limit pull force.
Knowing pull force is critical for applications like magnetic holding, lifting, and securing objects safely.the
Rare earth is commonly used to describe high energy magnet material such as NdFeB (Neodymium-Iron-Boron) and SmCo (Samarium-Cobalt).
Relative permeability (μ<sub>r</sub>) is a dimensionless measure of a material’s ability to conduct or transmit a magnetic field compared to a vacuum. It is calculated as μ<sub>r</sub> = μ / μ₀, where μ is the material’s absolute permeability and μ₀ is the permeability of free space (≈ 4π × 10⁻⁷ H/m). A relative permeability of 1 means the material conducts magnetic fields like a vacuum; values less than 1 indicate weaker conduction (diamagnetic materials), while values greater than 1 indicate stronger conduction (paramagnetic or ferromagnetic materials). Understanding μ<sub>r</sub> is important for applications such as transformers, inductors, and magnetic shielding.
Reluctance measures a material’s resistance to the passage of magnetic flux. It is calculated as the ratio of magnetomotive force (MMF) to magnetic flux and is the reciprocal of permeance. High reluctance indicates that a material resists magnetic flux, while low reluctance means it allows flux to pass more easily.
Remanence is the magnetic induction that remains in a magnetic material or circuit after the external magnetizing force has been removed. It represents the material’s ability to retain magnetization.
See Brmax.
See Brmax.
A magnetic return path is the route through which magnetic flux completes its circuit, returning from the North Pole to the South Pole of a magnet. In practical applications, materials with high magnetic permeability, such as iron or steel, are often used to guide the flux efficiently. Designing an effective return path is essential for maximizing the performance and efficiency of devices like transformers, motors, generators, inductors, and magnetic storage systems by minimizing flux leakage.
The Reversible Temperature Coefficient describes how a magnetic material’s properties change with temperature in a reversible way. It indicates the rate at which magnetic flux density (B<sub>r</sub>) or coercive force (H<sub>c</sub>) varies as temperature changes. Positive coefficients mean the property increases with temperature, while negative coefficients mean it decreases. These changes are reversible—returning the material to its original temperature restores its original magnetic properties. RTC is important for selecting magnetic materials in applications that operate across varying temperatures to ensure reliable performance.
Magnetic saturation is the state in which a material has reached its maximum magnetization, with nearly all magnetic domains aligned. Beyond this point, increasing the external magnetic field does not increase the magnetic flux density (B). Saturation is indicated by the flattening of the B-H curve and is important in applications like transformers and inductors, where core materials are operated near—but not beyond—their saturation point. Different materials have different saturation levels, with soft magnetic materials reaching saturation more easily than hard magnets such as neodymium.
A magnetic shunt is a path that diverts magnetic flux away from a certain area or component in a magnetic circuit. It is typically made of a material with low reluctance (high permeability), providing an easier path for the magnetic field lines. Shunts can be used to control flux distribution, protect sensitive components, or regulate magnetic circuits, but they may also reduce the magnetic field in certain areas if not properly managed.
S.I., short for Système International, refers to the International System of Units, also known as the MKS system. It is the standardized system used worldwide for measuring physical quantities.
The South Pole of a magnet is the end toward which magnetic field lines run from the North Pole. By convention, magnetic field lines flow from the North Pole to the South Pole. Interestingly, the Earth’s geographic North Pole acts as a magnetic South Pole, which is why the north end of a compass needle is attracted to it.
Magnet stabilization is the process of preparing a magnet to maintain reliable performance under specific conditions. This involves exposing the magnet to factors such as temperature, external magnetic fields, or mechanical stress to ensure its properties—like strength, magnetization direction, and stability—remain consistent. Protective coatings may also be applied to resist environmental effects like corrosion. Stabilization is essential for magnets used in motors, generators, sensors, and data storage devices to ensure long-term, consistent performance.
The Surface Field, or Surface Gauss, measures the magnetic field strength at the surface of a magnet. It is expressed in Gauss (G) or Tesla (T), with 1 Tesla equal to 10,000 Gauss. This value indicates the magnet’s strength near its surface, which decreases rapidly with distance. Surface Field measurements are important for applications such as electric motors, generators, magnetic therapy devices, and magnetic levitation systems, and are typically measured using a Gaussmeter.
The Temperature Coefficient measures how a material’s property changes with temperature, usually expressed as a percentage per degree Celsius (%/°C). In magnets, it commonly refers to the change in residual induction (B<sub>r</sub>) and coercive force (H<sub>c</sub>) with temperature. For example, a NdFeB magnet may have a negative B<sub>r</sub> temperature coefficient, meaning its magnetic strength decreases as temperature rises. Understanding this coefficient is important for selecting magnets that maintain optimal performance across varying temperatures.
Tesla is the S.I. unit for magnetic induction (flux density). One Tesla equals 10,000 Gauss.
A weber (Wb) is the SI unit of magnetic flux, representing the total quantity of magnetic field passing through a given area. Practically, 1 weber is defined as the amount of magnetic flux which, when linked uniformly with a single-turn electrical circuit over a time interval of 1 second, induces an electromotive force (EMF) of 1 volt in that circuit.
The weight of a single magnet.
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