Magnetic attraction – also known as adhesive force – describes the force with which a magnet attracts ferromagnetic materials such as iron, nickel or cobalt. It is expressed in newtons (N) (sometimes also in kilograms (kg); 10 N ≈ 1 kg) and depends on the magnetic material, the geometry and the air gap. The greater the distance, the weaker the force.
The relationship is F (force) = m (mass) * g, where g is the acceleration due to gravity and is usually given as approximately 9.81 m/s². The acceleration due to gravity depends on the distance between the test mass and the Earth’s centre of mass.

In addition to the attraction between a magnet and a ferromagnetic counter-armature, the attractive force (or pulling force) between two magnets or magnetic systems also plays an important role. Opposite poles (north–south) attract each other, whilst like poles (north–north or south–south) repel each other. The forces between magnets can be considerable – depending on their size and material – and must be taken into account during handling, assembly and design.

The air gap refers to the distance between a magnet and its ferromagnetic counterpart, or between two magnets or magnetic systems – a deliberate interruption of a material with high magnetic permeability (such as iron) by a medium with low magnetic permeability (such as air). It usually separates a moving component from a stationary one, so that they do not rub against each other mechanically. In permanent magnet systems, an air gap has a significant effect on the strength, direction and behaviour of the magnetic field.

In magnetic technology, the basic rule applies: the larger the air gap, the lower the system’s residual holding force. However, this apparent disadvantage often proves to be a technological advantage in design for contactless applications. It is only thanks to the air gap that magnets can rotate freely within motor housings, magnetic stirrers can operate sterilely through glass walls, or sensors can carry out precise measurements without wearing out. It converts magnetic forces into safe, wear-free motion. Magnetic energy is transmitted through the air gap and used to perform mechanical work – for example, to pull in the armature of a relay or to rotate the rotor of a motor.

At the same time, the air gap has a decisive influence on the holding force: when designing magnetic systems, minimising the air gap is a key design objective, as even a gap of just a few millimetres significantly reduces the force. Coatings, varnishes or contamination also act as an air gap and should be taken into account during the design process.

AlNiCo magnets consist of an alloy of aluminium, nickel and cobalt (iron and copper). Permanent magnets are produced from this material using casting or sintering techniques. AlNiCo magnets are characterised by high temperature resistance (in the range from -270°C to +450°C*) and good corrosion resistance. However, their coercive force is low, which means they can be easily demagnetised.

These magnets typically have a hardness of approx. 450–550 HV and can be machined using diamond tools (grinding, drilling), wire and die-sinking EDM, waterjet cutting, hard turning and hard milling. Due to their magnetic properties, AlNiCo magnets must have a considerable length in the direction of magnetisation in order to exhibit good resistance to demagnetisation when used as open magnets.

* However, the maximum operating temperature varies and depends largely on the specific alloy, the application, the materials involved and the geometry of the magnet. For precise details on the temperature range of your magnet system, please refer to our product catalogue or contact us for a personal consultation.

Antiferromagnetism is a specific form of magnetic order in which neighbouring atomic magnetic moments align exactly antiparallel to one another. They point in opposite directions and cancel each other out – the material therefore exhibits no measurable external magnetic field. Above the so-called Néel temperature, this order breaks down and the material becomes paramagnetic. Typical antiferromagnetic materials include manganese oxide, nickel oxide, haematite and chromium. They are used in spintronics and magnetic storage technologies.

Magnetic anisotropy describes the directional dependence of a material’s magnetic properties. Anisotropic magnets have a preferred direction of magnetisation, which is determined by an external field during manufacture. As a result, they achieve significantly higher energy products than isotropic magnets. This distinction is crucial for selecting the right magnet for technical applications. The axis of anisotropy can also be precisely measured in permanent magnets, in terms of a relative misalignment or angular deviation.

In axial magnetisation , the direction of magnetisation runs along one of the magnet’s axes, with the north and south poles located on the opposite end faces. For cylindrical magnets and rings, this is unambiguously the longitudinal axis (height).
With rectangular magnets, however, three axes are possible – the magnetisation can run along the length, width or height. The exact direction of magnetisation must therefore always be specified for rectangular magnets. Axial magnetisation is particularly suitable for holding applications, fasteners and sensors.

Further information can be found under M: Types of magnetisation

It is also possible to magnetise axially in a sector-shaped pattern. Sector-shaped magnetisation means that a material is not magnetised uniformly, but has different magnetic forces or directions in different areas.

A back yoke is a component made of ferromagnetic material that closes the magnetic field lines at the rear of a magnet. It operates on the same principle as a magnetic yoke and enhances the holding force on the working side. At the same time, it shields the stray field at the rear. Closing pieces are an essential component of pot magnets and flat pot magnets.

Bipolar magnetisation is the standard form of magnetisation, with one north pole and one south pole. The term is used to distinguish it from multipole magnetisations. Depending on the geometry, a distinction is made between axial two-pole magnetisation (poles on the end faces) and diametric two-pole magnetisation (poles on the lateral faces).

The B-field – also known as magnetic flux density – describes the strength and direction of a magnetic field. The units are tesla (T), millitesla (mT) or gauss. The B-field indicates how many magnetic field lines per unit area pass through a given region. It is the key quantity used to characterise magnetic fields in engineering and physics.

The BH curve – also known as a hysteresis curve or hysteresis loop – shows the magnetisation behaviour of a material as a function of the external magnetic field. It graphically illustrates the relationship between magnetic field strength (H) and magnetic flux density (B). Important parameters such as remanence, coercive field strength and energy product can be read from it. It is indispensable for material selection and magnet design.

The maximum energy product (BH)max is the most important performance indicator for permanent magnets. It indicates the maximum magnetic energy that a magnet can store per unit volume. The unit is kilojoules per cubic metre (kJ/m³) or megagauss-oersted (MGOe). The higher the energy product, the more powerful and compact a magnetic system can be designed.

The breaking force indicates the maximum tensile load that a magnetic system can withstand before the connection breaks or the material is damaged. It is not the same as the holding force and is determined under defined test conditions. This is important for safety-critical applications in industry and engineering.

Permanent magnets – particularly neodymium and ferrite – are brittle and break easily when subjected to mechanical stress. They should never be drilled, sawn or subjected to heavy stress. Splinters may cause injury when handling them. For applications subject to mechanical stress, magnet systems with protective housings are recommended.

The coating protects sensitive magnetic materials from corrosion and mechanical wear. Neodymium magnets in particular require surface protection, as they are highly susceptible to oxidation. Common coatings for magnets include nickel (nickel-copper-nickel), zinc, gold, epoxy resin, or combinations of nickel and epoxy resin, or zinc and parylene. The choice of coating depends on the operating environment (e.g. contact with water), temperature and mechanical stress.

The coercive field strength indicates the counter-field required to completely demagnetise a magnet. It is a measure of resistance to demagnetisation. A distinction is made between Hc (coercive field strength of flux density) and HcJ (coercive field strength of polarisation). The higher the value, the more stable the magnet is in the face of temperature changes and counter-fields.

Put simply: the coercive field strength Hc describes the magnetic field strength required to cause the magnetic induction in the magnet to disappear. This occurs when a permanent magnet is placed in a magnetising field with opposite polarity and a coercive field strength of Hc.

The measurement is carried out by means of a hysteresis measurement in a permeameter, in which the magnet is exposed to an increasing counter-field until the flux density (B) or polarisation (J) reaches zero. For rapid batch testing, coercimeters are used, which directly detect the zero-crossing point and display the coercive field strength.

The Curie temperature is the critical temperature at which a ferromagnetic material loses its magnetic properties. Above this point, the magnet becomes paramagnetic – the magnetic order breaks down. For neodymium magnets, it is around 310 °C; for ferrites, around 450 °C. This is crucial for high-temperature applications.

Also of interest is the effect of cold on magnetic materials
Up to -40 °C, the holding force increases slightly. From -125 °C, it decreases; at -196 °C, 85–90 % remains (reversibly).

Declination refers to the angle between magnetic north and true north at a specific location. It arises because the magnetic North Pole does not coincide exactly with the true North Pole. Knowledge of the local declination is essential for navigation and surveying.

Demagnetisation refers to the partial or complete loss of magnetisation in a permanent magnet. This can be caused by high temperatures, strong counter-fields, mechanical shocks or vibrations, or an unfavourable magnetic circuit design. The susceptibility to demagnetisation depends on the magnetic material and its coercive field strength. Neodymium magnets, for example, are more sensitive to demagnetisation than ferrites, but offer higher performance. (See also Demagnetisation / Demagnetisation curve)

In diametrical magnetisation, the direction of magnetisation runs across the diameter of a cylindrical or ring-shaped magnet. The north and south poles face each other on the outer surfaces. This type of magnetisation is frequently used for rotors in brushless motors, sensors and encoders. It enables a uniform field distribution during rotational movements.

Diamagnetism is a weak form of magnetism that occurs in all materials. Diamagnetic substances are slightly repelled by a magnetic field, as they generate a weak counter-field. The effect is very slight and is usually masked by stronger magnetic properties. Typical diamagnetic materials include water, copper, gold and bismuth.

A disc magnet is a flat, cylindrical permanent magnet with a height that is small in relation to its diameter. The magnetisation is usually axial – the poles are located on the two flat sides. Disc magnets are particularly suitable for holding applications, fastenings and sensor technology. They are available in a wide range of sizes and materials.

A magnetic dipole is the basic unit of a magnetic field, consisting of a north pole and a south pole (see diagram). Unlike electric charges, magnetic poles never occur in isolation – every magnet always has both poles. This principle applies from the smallest elementary magnet to the largest industrial magnet.

Eddy currents are circular electric currents induced in conductive materials by time-varying magnetic fields. They cause energy losses in the form of heat and can lead to heating in permanent magnets. In engineering, eddy currents are specifically used for induction heating, eddy current brakes and non-destructive material testing. In transformers and motors, however, they are undesirable.

An eddy current brake utilises the principle of electromagnetic induction to slow down moving metal parts without physical contact. When a conductive material (e.g. an aluminium or copper disc) is moved through a magnetic field, eddy currents are generated which create a counter-field and slow down the movement. The braking energy is converted into heat. Eddy current brakes operate without wear, require little maintenance and are used in commercial vehicles, rail vehicles, roller coasters and test benches. Depending on the design, either permanent magnets or electromagnets are used. As part of our specialist system engineering work, we already have some experience in this field of technology. If you have a project enquiry, please do not hesitate to contact us.

An electromagnet generates a magnetic field through an electric current flowing through a coil. Unlike permanent magnets, its field strength can be adjusted and switched on or off. The magnetic field is amplified by an iron core inside the coil. Electromagnets are used in relays, lifting magnets, solenoid valves and industrial lifting equipment.

Elementary magnets are the smallest magnetic units in a material – they arise from the spin motion of electrons. In their unmagnetised state, they are randomly aligned and cancel each other out. When exposed to an external magnetic field, they align themselves in parallel and the material becomes magnetic. This model clearly explains the origin of magnetism at the atomic level.

Epoxy coating is a form of corrosion protection for magnets, involving the application of a thin layer of synthetic resin. It offers good protection against moisture and chemical influences. Epoxy is particularly suitable for applications involving low mechanical stress. The coating is usually black and slightly thicker than metallic coatings.

Magnetic field lines are a model used to represent magnetic fields. Outside the magnet, they run from the north pole to the south pole, forming closed loops. The closer together the field lines are, the stronger the magnetic field at that point. The field line model helps with the visualisation and calculation of magnetic interactions.

Ferrite magnets – also known as ceramic magnets – are made of iron oxide and barium carbonate or strontium carbonate. They are cost-effective, corrosion-resistant and temperature-stable up to around 250 °C. Typical applications: loudspeakers, motors, magnetic boards and fastening systems.

Ferrimagnetism is a form of magnetic order in which neighbouring atomic moments align antiparallel to one another – but with different magnitudes. This results in a measurable external magnetic field. Ferrites are typical ferrimagnetic materials. The effect lies between ferromagnetism and antiferromagnetism.

Ferromagnetism is the strongest form of magnetism and is responsible for the properties of permanent magnets. In ferromagnetic materials, the atomic magnetic moments align parallel to one another and reinforce each other. Typical ferromagnetic materials (elements) include iron, cobalt and nickel. Above the Curie temperature, they lose their ferromagnetic properties.

Magnetic flux density ( also known as the B-field) describes the strength of a magnetic field at a specific point in space. Put simply, it indicates how many magnetic field lines pass through a surface perpendicular to the field per unit area.

• Physical significance: It is a measure of the local concentration of magnetic flux. The higher the flux density, the stronger the magnetic force acting on moving charges or ferromagnetic materials.
• Unit:
  • The SI unit is the tesla (T)
  • In practice, the gauss (G) is still often used
  • Conversion: 1 Tesla = 10,000 Gauss

When we at BRUGGER talk about the ‘strength’ of a magnet (e.g. on the surface of a permanent magnet), technically speaking we almost always mean the magnetic flux density. This is the key factor in determining how strongly a magnet attracts a workpiece or how effectively it filters metal shavings from a medium.

Flux measurement is used to determine the magnetic flux of a permanent magnet. A fluxmeter is used as the measuring instrument; this integrates the voltage induced in a measuring coil. The measuring coil either encloses the magnet or is moved past it. The result is the magnetic flux in Weber (Wb). This method is particularly suitable for quality control and the classification of magnets in mass production, as it is quick and non-destructive.

A flux meter is a measuring instrument used to determine magnetic flux. It integrates the voltage induced in a measuring coil over time and displays the result in Weber (Wb). Modern fluxmeters are digital and enable automated measurement processes. They are used in magnet manufacturing for quality control and classification.

The magnetic focal point refers to the area of highest magnetic field concentration in specially shaped magnetic systems. Through the careful design of the pole pieces, the magnetic energy can be focused onto a small area. This principle is used, for example, in holding magnets or in sensor technology.

The gauss (G) is an older unit of magnetic flux density that is still in use, particularly in the United States. The SI unit is the tesla (T). The conversion is: 1 Tesla = 10,000 gauss. Both units are used interchangeably in data sheets and technical literature.

A gauss meter – also known as a teslameter – is a measuring instrument used to determine magnetic flux density. The sensor is usually a Hall probe, which converts the magnetic field into an electrical signal. Gaussmeters are used for quality control of permanent magnets, for field measurements in magnetic systems and for testing shielding. The term ‘Gaussmeter’ is commonly used in the US; ‘teslameter’ corresponds to the SI nomenclature.

The grade indicates the performance level of a magnetic material and defines its magnetic properties, such as energy product, remanence and coercive field strength. Each group of magnetic materials has its own classification system:

Neodymium magnets (NdFeB): Designations such as N35, N42 or N52 indicate the maximum energy product in MGOe. Additional letters such as M, H, SH or UH denote increased temperature resistance.

Ferrite magnets: Grade designations such as Y10, Y25, Y30 or Y35 describe performance. Higher numbers indicate higher energy products. The designations may vary depending on the manufacturer (e.g. HF, C8).

AlNiCo magnets: Classifications such as AlNiCo 5, AlNiCo 8 or AlNiCo 9 differ in terms of energy product and coercive field strength. Higher numbers usually indicate improved magnetic properties.

Samarium-cobalt magnets (SmCo): There are two main groups – SmCo5 (1:5) and Sm2Co17 (2:17). Within these groups, there are further sub-categories based on energy product and temperature behaviour.

Choosing the right grade is crucial for the performance and cost-effectiveness of a magnet system. You can find the magnetic grade and other key figures for our materials under M – Magnet Material Data.

The holding force indicates the force required to pull a magnet vertically away from a steel surface (also known as the attractive force or tensile force). It is expressed in newtons (N) or kilograms (kg) and is measured under standardised conditions. The actual holding force depends on the surface finish, the air gap and the material thickness. It is a key selection criterion for magnet systems.

The holding force of a magnet depends largely on the material and thickness of the counter-armature. Optimal values are achieved with a counter-armature plate made of unalloyed structural steel (e.g. S235). The thickness should be selected so that the counter-armature can fully accommodate the magnetic flux – if it is too thin, oversaturation occurs and some of the field lines are ‘lost’. They extend outside the counter-armature and can therefore no longer ‘take effect’. Inferior or non-ferromagnetic materials (e.g. austenitic stainless steel) also significantly reduce the holding force.

The holding force of a magnet decreases disproportionately as the air gap increases – even a gap of just a few tenths of a millimetre can reduce the force by 50 per cent or more. As well as physical distance, air gaps can also be caused by coatings, paints, films, contamination or rough surfaces, all of which must be taken into account during the design phase.

The effect of an air gap varies depending on the type of magnet: flat pot magnets are particularly sensitive, as the magnetic flux is distributed over a wide area and is highly concentrated. Deep pot magnets and A-systems exhibit different characteristic curves to those shown in this schematic diagram and, depending on their design, may be more tolerant of small gaps.

Generally speaking, the holding force of any magnetic alloy decreases as the temperature rises. The maximum operating temperature specified in our product descriptions indicates the temperature up to which the systems can be used without risk of damage. If this limit is exceeded, it will affect plastics, adhesives and/or the magnetic force. Please therefore observe the relevant temperature specifications for the maximum operating temperature of our magnetic systems.

A Hall sensor measures magnetic fields based on the Hall effect. When a current-carrying conductor is exposed to a magnetic field, a measurable voltage is generated across the conductor, perpendicular to the direction of the current. Hall sensors are used for non-contact position and speed detection. They are found in smartphones, vehicles and industrial control systems, as well as in the measuring instruments described under gaussmeters (teslameters).

A Halbach array is a special arrangement of magnets in which the direction of magnetisation rotates in steps – typically in 90° increments. As a result, the magnetic field is significantly strengthened on one side, whilst it is virtually cancelled out on the opposite side. This asymmetrical field distribution enables more compact and efficient magnetic systems. Halbach arrays are used in linear motors, magnetic bearings, holding systems and particle accelerators. We have already had the opportunity to assemble a Halbach array in collaboration with a university; if you are interested in a project of this kind, please feel free to contact our Technical Application Consultants via the contact form.

A Hall probe is the precision measuring head of a gauss meter or teslameter used to determine magnetic flux density. It consists of a thin semiconductor wafer positioned perpendicular to the magnetic field. The resulting Hall voltage is proportional to the flux density and is analysed by the connected measuring instrument. Hall probes enable calibrated measurements ranging from millitesla to tesla and are indispensable in the quality control of magnets.

Hard magnetic materials are difficult to magnetise, but retain their magnetisation permanently. They have a high coercive field strength and are therefore suitable for permanent magnets. Typical hard magnetic materials include neodymium, ferrite and SmCo. The opposite of these are soft magnetic materials.

Hard magnetic ferrites are produced from iron oxide and strontium carbonate or barium carbonate.
Strontium ferrite composition:_{SrFe₁₂O₁₉}
Barium ferrite composition:_{BaFe₁₂O₁₉}

These magnets have a hardness of 480–580 HV and can be machined using diamond tools or waterjet cutting.Unlike rare-earth magnets, ferrites have a significantly lower magnetic energy density. These raw materials are available in large quantities and are therefore very inexpensive.

Chipping on sharp edges of the ferrites is permissible provided that the original shape of the magnet – and thus its function – is retained. If 100% flawless edges are required, this must be explicitly stated. Minor cracks in the magnetic material have no effect on the holding force.

HF magnets can be isotropic (no preferred orientation of the elementary particles -> lower holding force) or anisotropic (elementary particles are oriented in a preferred direction -> higher holding force). HF magnets can be used in temperature ranges from -40°C to +250°C*.
The material is hard and brittle; machining is only possible using diamond tools. Furthermore, HF is resistant to oxidation and weathering and exhibits good chemical resistance.

* However, the maximum operating temperature varies and depends largely on the specific alloy, the application, the materials being joined, and the geometry of the magnet. For precise details regarding the temperature range of your magnet system, please refer to our product catalogue or contact us for a personal consultation.

A Helmholtz coil consists of two parallel, identical coils arranged at a distance equal to their radius from one another, through which current flows in the same direction. A particularly homogeneous magnetic field is generated at the centre between the two coils. This arrangement is used to calibrate magnetic field sensors, to measure the magnetic moments of permanent magnets and to compensate for interfering environmental fields such as the Earth’s magnetic field.

The H-field describes the magnetic field strength independently of the surrounding material. The unit is ampere per metre (A/m) or oersted (Oe). Whilst the B-field indicates the actual flux density, the H-field describes the cause of the magnetic field. Both quantities are linked via the material’s permeability.

Hysteresis describes the delayed response of a ferromagnetic material to changes in the external magnetic field. Magnetisation does not follow a linear path, but instead forms a characteristic loop – the hysteresis curve (which can be viewed here on Wikipedia). This curve shows that permanent magnets retain their magnetisation and that energy losses occur when their polarity is reversed.

Hysteresis measurement is a method for recording the complete BH curve of a magnetic material. The test specimen is cyclically magnetised and demagnetised within a closed magnetic circuit, whilst the field strength and flux density are continuously recorded. Important parameters such as remanence, coercive field strength and energy product can be derived from the measurement. It is indispensable for material characterisation and quality assurance.

Magnetic induction refers to the generation of an electrical voltage in a conductor as a result of a changing magnetic field. This principle – described by Faraday’s law of induction – forms the basis for generators, transformers and sensors.

Isotropic magnets have no preferred direction of magnetisation and can be magnetised in any direction. They are manufactured without being aligned in a magnetic field and therefore achieve lower energy products than anisotropic magnets. Their flexibility makes them suitable for applications involving complex magnetisation patterns or where the direction of magnetisation is only determined after manufacture.

Irreversible losses refer to the permanent loss of magnetic strength, which cannot be reversed simply by cooling or removing a counter-field. This is caused by exceeding the maximum operating temperature or exposure to excessively strong demagnetising fields. The magnet must then be remagnetised to restore its original performance.

Yoke / Magnetic yoke

A yoke is a component made of soft magnetic material that specifically guides and concentrates magnetic field lines. It connects the poles of a magnet or electromagnet and closes the magnetic circuit. The use of a yoke significantly increases the holding force of a magnetic system and minimises stray fields. Typical materials include soft iron or structural steel.

Yoke magnet

Refers to a complete magnetic system consisting of a permanent magnet and an iron yoke. In other words: magnet + yoke = yoke magnet.
A yoke magnet is a magnetic system in which a permanent magnet is embedded in a housing made of soft magnetic material. The iron yoke concentrates the field lines and significantly increases the holding force at the pole face. An example of a yoke magnet is a so-called ring-gap system. Transformers are also applications of yoke magnets.

Lifting capacity is a practical term for holding force and indicates the weight a magnet can hold on a steel surface. It is usually stated in kilograms and measured under ideal conditions. In practice, the actual holding force is often lower – depending on the air gap, surface finish and counter-anchor. The term is frequently used in the retail sector and in end-user applications.

Longitudinal magnetisation is another term for axial magnetisation in bar magnets. The poles are located at both ends of the magnet. This type of magnetisation is standard for cylindrical and rectangular magnets used for gripping and holding applications.

The Lorentz force is the force exerted by a magnetic field on moving electric charges (e.g. electrons). It is the link between electricity and magnetism and the reason why charged particles can be deflected in a magnetic field.

The principle:

• Stationary charges do not experience any force in a magnetic field.
• Moving charges cross the field lines of the magnetic field and are therefore subjected to a force.
• Direction of action: The Lorentz force always acts perpendicular to both the direction of the particle’s motion and the direction of the magnetic field

The force can be determined using the three-finger rule of the right hand:

• Thumb: direction of motion of the charge (for positive charges = technical direction of current)
• Index finger: direction of the magnetic field (from the north pole to the south pole)
• Middle finger: direction of the Lorentz force (direction of force)

Magnet
A magnet is a body that generates a permanent magnetic field and attracts ferromagnetic materials. A distinction is made between permanent magnets and electromagnets. Every magnet has a north pole and a south pole – like poles repel each other, whilst unlike poles attract each other. Magnets are used in almost all areas of technology.

magnetic system
A combination of a magnet with other components made of metal and/or plastic. A magnetic system is an assembly comprising one or more magnets in combination with other components such as a yoke, pole shoes or a housing. The specific arrangement optimises the holding force, field distribution or switching behaviour. Typical magnetic systems include pot magnets, gripper systems, magnetic fasteners and holding elements. They achieve higher performance than individual magnets.

A magnetic field is the space around a magnet in which magnetic forces act. It is represented by field lines running from the north pole to the south pole. The strength of the field decreases as the distance from the magnet increases. Magnetic fields are generated by permanent magnets, conductors carrying an electric current, or moving electric charges.

The magnetic grade (also known as the quality class ) describes the performance and quality of a magnet. It indicates how strong the magnet is and what temperatures it can withstand. The magnetic grade serves as a standardised ‘performance rating’ for engineers and purchasers. The higher the number, the stronger the magnet, all other things being equal.

Breakdown of the grade designation using the example N45H:

• Letter N = Neodymium: The capital N at the start of the grade designation (as in N45 or N52) immediately indicates to the user that it is a neodymium magnet
• Number (e.g. 45): Represents the magnetic force. The higher the number, the stronger the magnet.
• Letter (e.g. H): Indicates the maximum operating temperature (e.g. H = up to 120 °C).

Tabular summary of magnetic materials

The magnetic moment is a physical quantity that describes the strength and direction of a body’s magnetic effect. In the case of permanent magnets, it indicates how strongly the magnet interacts with external magnetic fields. The unit is the ampere-square metre (A·m²) or joule per tesla (J/T). The magnetic moment is independent of the magnet’s geometry and is therefore ideal for comparing different magnets. It is typically measured using a Helmholtz coil in combination with a fluxmeter.

A magnetising device is used to magnetise permanent magnets. In industrial manufacturing, pulse magnetisers are predominantly used; these reliably magnetise even high-coercivity materials using short, strong magnetic field pulses. For simple applications, magnetising yokes with permanent magnets or electromagnets are also available. See also ‘Pulse magnetisers’.

Magnetisation refers to the process by which a ferromagnetic material itself becomes a magnet. This occurs through the alignment of the elementary magnets within the material by means of a strong external magnetic field. Magnetisation can be permanent (in hard magnets) or temporary (in soft magnets). The unit of magnetisation is ampere per metre (A/m).

Methods of magnetisation

By means of an external magnetic field: The material is placed within the strong field of an electromagnet (often a coil through which current is passed). This causes the atomic magnets to align. In this way, permanent magnetism can be produced in manufacturing.
By mechanical stroking: Repeatedly stroking a piece of iron (e.g. a nail) with a permanent magnet in the same direction forces the elementary magnets into a parallel alignment.
By heating and cooling (thermomagnetism): This method exploits the fact that the magnetic properties of certain alloys are highly dependent on temperature. One such material, for example, is an alloy of the elements lanthanum, iron, cobalt and silicon, which has previously been used for magnetic refrigeration applications.
Below approximately 27 °C, the material is magnetic, whilst at higher temperatures it is non-magnetic.
If the material is alternately brought into contact with warm and cold water, its magnetisation changes continuously.

All magnetic systems supplied by us are manufactured with the same magnetisation as standard, i.e. the arrangement of the poles on the adhesive surface is always the same for each alloy.
Here is a schematic diagram of the various magnetic alloys:

Magnetism is a physical phenomenon, a sub-field of electromagnetism, which is one of the four fundamental forces of physics. Magnetism is described using the magnetic field H and the magnetic flux density B. Magnetism arises from moving electric charges or from magnetic (orbital) moments and the intrinsic moments (spin) of electrons. Magnetism manifests itself as a force mediated by the magnetic field, either emanating from magnetic objects (such as permanent magnets) or acting upon them (such as iron).

The magnetic core refers to the permanent magnet as the central element of a magnetic system. It forms the source of the magnetic field and serves as a reference for the holding force. When combined with a housing made of soft magnetic steel – for example, as a steel pot, a pole shoe system or with a back-gap – the field lines are concentrated and the holding force is significantly increased compared with that of the magnet core alone.

Magnetic flux – also known as magnetic flow – describes the total number of magnetic field lines passing through a given area. The unit is the Weber (Wb). Magnetic flux is the product of magnetic flux density and the area through which it passes. It is a key parameter in the calculation of magnetic circuits and induction processes.

A magnetic circuit describes the closed path along which magnetic field lines flow. It consists of a magnetic source, magnetic conductors (e.g. an iron yoke) and, where applicable, air gaps. The design of the magnetic circuit determines the efficiency and performance of a magnetic system. As with an electrical circuit, certain laws apply, such as the law of magnetic flux.

Magnetic alloys are metallic materials which, through a combination of different elements, acquire strong permanent magnetic properties. The most important magnetic alloys are neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo) and aluminium-nickel-cobalt (AlNiCo). Each alloy offers specific advantages in terms of energy product, temperature resistance and corrosion behaviour. The magnetic properties arise from the alloy’s crystalline microstructure.

A magnetometer is an instrument used to determine the strength and direction of a magnetic field. There are various types, such as Hall probes, fluxgate magnetometers and SQUID sensors. Magnetometers are used in geophysics, navigation, quality control and materials testing. Their measurement accuracy ranges from femtotesla to several tesla.

A magnetic coupling transmits torque between two shafts without physical contact, using magnetic forces. It consists of two separate halves containing permanent magnets, which are magnetically coupled through a partition. The major advantage is that the drive and driven sides are hermetically sealed off from one another, making the coupling ideal for pumps, agitators and compressors handling aggressive, toxic or high-purity media. Magnetic couplings operate without wear, require no seals at the shaft passage and are low-maintenance. In the event of an overload, they slip, thereby protecting the drive from damage. Our experts have already successfully implemented numerous projects involving magnetic couplings – please contact our technical sales team with any enquiries.

Every magnet has two poles – a north pole and a south pole. The magnetic field lines emerge at the north pole and re-enter at the south pole. Magnetic poles never occur in isolation – if a magnet is split, two new complete magnets are formed, each with two poles. The naming convention is derived from the Earth’s magnetic field: the north pole of a compass needle points towards the Earth’s magnetic north pole.

• North pole: The pole that aligns with the Earth’s geographic North Pole. It is usually marked in red (e.g. on traditional educational magnets).
• South Pole: The pole that aligns with the Earth’s geographic South Pole. It is usually marked in green or blue.
• Dipole: An object with two opposite poles. As magnets always possess both poles simultaneously, they are always magnetic dipoles. There are no isolated individual north or south poles (monopoles) in nature. If a magnet is split down the middle, this simply creates two new, smaller dipoles, each with its own north and south poles.

The Arctic magnetic pole is not fixed in position, but shifts constantly in a multi-layered pattern:
https://de.wikipedia.org/wiki/Nordpol

Magnetic materials are materials suitable for the manufacture of permanent magnets. The most important ones are neodymium-iron-boron (NdFeB), samarium-cobalt (SmCo), ferrite and aluminium-nickel-cobalt (AlNiCo). They differ in terms of energy product, temperature resistance, susceptibility to corrosion and price. The choice depends on the specific requirements of the application.

Neodymium-iron-boron (NdFeB)

An alloy of neodymium, iron and boron with the composition_{Nd₂Fe₁₄B}.
NdFeB magnets have a hardness of 560–580 HV and are less brittle than HF and SmCo alloys. The material can be machined using diamond tools and wire and die-sinking EDM. Due to the high rate of oxidation in their raw state, they are predominantly supplied nickel-plated or zinc-plated. NdFeB magnets have a very high energy density, meaning that very high holding forces can be achieved at maximum saturation. Depending on the composition of the alloy, they can be used in temperature ranges from –40°C to +200°C*.

Samarium-cobalt (SmCo)

An alloy of the rare-earth metal samarium (Sm) with the metal cobalt (Co).
Alloy structures:
_SmCo5 (without iron content)
_{Sm₂Co₁₇} (with 20–25% iron content)

These magnets have a hardness of 500–700 HV and are therefore brittle. They can be machined using diamond tools and wire and die-sinking EDM. Due to their high cobalt content, they are more expensive than other magnetic materials. SmCo magnets oxidise only slightly and exhibit good chemical resistance. Thanks to their high energy density (approx. 30–40% less than NdFeB magnets), high holding forces can be achieved at maximum saturation. They can be used in temperature ranges from -40°C to +350°C*. Minor cracks in the magnet material do not affect the holding force.

Aluminium-nickel-cobalt (AlNiCo)

Alloys of aluminium, iron, nickel, copper and cobalt. Permanent magnets are produced from these using casting or sintering techniques.

These magnets have a hardness of 510 HV and can be machined using diamond tools (grinding, drilling), wire and die-sinking EDM, waterjet cutting, hard turning and hard milling. Due to their magnetic properties, AlNiCo magnets must have a considerable length in the direction of magnetisation in order to exhibit good resistance to demagnetisation when used as open magnets. AlNiCo magnets are highly temperature-resistant and can be used in ranges from -270°C to +450°C*.

Hard magnetic ferrites (HF)

These are manufactured from iron oxide and strontium carbonate.
Strontium ferrite composition:_{SrFe₁₂O₁₉}

These magnets have a hardness of 480–580 HV and can be machined using diamond tools or water jet cutting.In contrast to rare-earth magnets, ferrites have a significantly lower magnetic energy density. These raw materials are available in large quantities and are therefore very inexpensive.

Chipping on sharp edges of the ferrites is permissible provided that the original shape of the magnet – and thus its function – is retained. If 100% flawless edges are required, this must be explicitly stated. Minor cracks in the magnetic material do not affect the holding force.

HF magnets can be isotropic (no preferred orientation of the elementary particles -> lower holding force) or anisotropic (elementary particles are oriented in a preferred direction -> higher holding force). HF magnets can be used in temperature ranges from -40°C to +250°C*.
The material is hard and brittle; machining is only possible using diamond tools. Furthermore, HF is resistant to oxidation and weathering and exhibits good chemical resistance.

* However, the maximum operating temperature varies and depends largely on the specific alloy, the application, the materials being joined, and the geometry of the magnet. For precise details on the temperature range of your magnet system, please refer to our product catalogue or contact us for a personal consultation.

Multipole magnetisation refers to the creation of several alternating north and south poles on a single magnet. The term is used synonymously with multipole magnetisation. Typical applications include sensor magnets, encoders and rotors for brushless motors.

A measuring coil is a passive wire winding used to measure magnetic flux by means of electromagnetic induction. It is connected to a flux meter and either passed past the magnet or wound around it. The changing magnetic field induces a voltage, which is integrated by the fluxmeter – the result is the magnetic flux in weber. Typical designs include ring coils for total flux measurement and flat coils for surface measurements.

In multipole magnetisation , several north and south poles are created on a single magnet. The poles alternate at regular intervals – arranged radially, axially or linearly. This type of magnetisation is used for sensors, encoders, brushless motors and rotary encoders. The number of poles influences the resolution and accuracy of the application. The term‘multipole magnetisation’ may also be used.

The Néel temperature is the critical temperature at which an antiferromagnetic material loses its magnetic order. Above this point, the material becomes paramagnetic. It is the equivalent of the Curie temperature in ferromagnetic materials. It is named after the French physicist Louis Néel, who was awarded the Nobel Prize in 1970 for his research into magnetism.

Neodymium magnets consist of an alloy of neodymium, iron and boron, and are the strongest permanent magnets available today. They achieve energy products of over 50 MGOe and enable extremely compact magnetic systems. Their weaknesses are susceptibility to corrosion and limited temperature resistance (80–200 °C, depending on grade). Neodymium-iron-boron magnets are predominantly used in applications such as electric motors, loudspeakers, wind turbines and magnetic holding systems.

Nickel plating is the most common form of corrosion protection for neodymium magnets. A three-layer nickel-copper-nickel coating is usually applied, which offers good protection and a shiny surface. Nickel-plated magnets are suitable for most standard applications. In the case of nickel allergies or corrosive environments, alternative coatings such as epoxy or gold should be chosen.

Every magnet has two poles – the north pole and the south pole. The field lines emerge at the north pole and re-enter at the south pole. Like poles repel each other, whilst unlike poles attract each other. By definition, the north pole of a freely rotating compass needle points towards the Earth’s magnetic north pole – which, physically speaking, is a magnetic south pole.
What’s more, one of the meeting rooms at BRUGGER is called ‘North Pole’ :-)

Nuclear magnetisation refers to magnetisation caused by the influence of the atomic nucleus – as opposed to the electron shell. The effect is extremely weak and is of no significance for permanent magnets. However, it forms the basis of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) in medical technology.

The oersted is the older CGS unit for magnetic field strength (H-field). It is still in use, particularly in the United States. The SI unit is the ampere per metre (A/m). The conversion is: 1 oersted = 79.58 A/m. In data sheets, the coercive field strength is often given in oersteds or kilo-oersteds (kOe).

Magnetic orientation indicates the direction of magnetisation within a magnet. In the case of anisotropic magnets, this preferred direction is determined during manufacture by an external field. A distinction is made between axial, diametric and multipolar orientation. Correct specification of the orientation is crucial for the magnet’s performance in the application.

The operating point indicates the operating state of a permanent magnet within a magnetic circuit. It is determined by the point where the demagnetisation curve intersects the shear line. The position of the operating point influences the usable magnetic force and the stability against demagnetisation. An optimal design ensures maximum efficiency and longevity of the magnet system.

Overview of the maximum operating temperature for magnets:

The maximum operating temperature indicates the temperature up to which magnets can be used; it depends on the magnetic material used. Generally speaking, the holding force of magnetic systems decreases as the temperature rises. The maximum operating temperature varies considerably, ranging from a standard 80 °C for conventional neodymium magnets to as high as 450 °C for Alnico magnets. If this temperature-dependent threshold is exceeded (the temperature rises above the so-called Curie temperature), this leads to irreversible demagnetisation, meaning that the magnet loses some or all of its holding force.

Overview of operating temperatures by material

The three stages of magnetism loss

When a magnet is heated, its internal structure begins to vibrate. A distinction is made between three stages of loss of strength:

1. Reversible loss: The magnet temporarily loses strength when heated. Once it cools back down to room temperature, it regains its full strength automatically.
2. Irreversible loss: If the maximum operating temperature is exceeded, the internal structures permanently rearrange themselves. The magnet remains weaker even after cooling, but can be remagnetised using a strong external magnetic field.
3. Permanent loss (Curie temperature): Once this point is reached, the magnetic alignment breaks down completely. The magnet becomes permanently demagnetised and is irreparably destroyed.

Key factors in everyday use

• Geometry: Thin or very small magnets are more sensitive to heat and demagnetise more quickly than thick, compact magnet blocks made of the same material.
• Metal counterparts: A magnet adhering directly to a piece of iron can physically withstand slightly higher temperatures than a free-floating magnet.
• Magnetic tapes and films: These flexible magnets are usually made from plastics and suffer permanent damage at temperatures as low as 80 °C to 85 °C.

Paramagnetism is a weak form of magnetism in which atomic magnetic moments partially align with an external field. Paramagnetic materials are slightly attracted to magnetic fields, but do not retain any magnetisation once the field is removed. Typical paramagnetic substances include aluminium, platinum and oxygen. The effect is considerably weaker than ferromagnetism.

A permanent magnet – also known as a lasting magnet – generates a constant magnetic field without any external energy supply. Once magnetised, it retains its magnetic properties permanently. The most important permanent magnet materials are neodymium (NdFeB), samarium-cobalt (SmCo), ferrite and AlNiCo. Permanent magnets form the basis for countless technical applications.

Permanent magnets – also known as permanent magnets – generate a constant magnetic field without an external power supply. They retain their magnetisation over long periods of time. Common materials include neodymium (NdFeB), ferrite, SmCo and AlNiCo. Applications range from motors and loudspeakers to fastening systems.

Magnetic permeability ( ) describes a material’s ability to allow magnetic field lines to pass through it. Materials with high permeability (such as soft iron) conduct magnetic fields well, whilst those with low permeability (such as air or copper) do so poorly. Relative permeability (µr) indicates the ratio to the permeability of a vacuum. It is crucial for the calculation of magnetic circuits.

A pole shoe is a component made of ferromagnetic material that is attached to a magnetic pole to shape and concentrate the magnetic field. It increases the pole face area or focuses the field lines onto a defined area. Pole shoes increase the holding force and improve the field distribution in magnetic systems. Typical examples of applications include pole shoe systems for high-holding-force applications with a small holding surface area, electromagnets, ...

Magnetic polarisation (J) describes the material’s contribution to the magnetic flux density. It results from the alignment of the atomic magnetic moments. The unit is the tesla (T). Polarisation is particularly relevant for the characterisation of permanent magnets and the calculation of the intrinsic coercive field strength (HcJ).

The pole spacing refers to the distance between the north and south poles of a magnet, or between adjacent poles in multipole magnets. It influences the range and geometry of the magnetic field. In sensor magnets, the pole spacing determines the resolution and signal quality. The smaller the pole spacing, the more steeply the field decreases with distance.

A pot magnet is a magnetic system in which a permanent magnet is embedded in a steel pot. The steel pot acts as a confining body and concentrates the field lines at the pole face. As a result, a pot magnet achieves a holding force many times greater than that of a comparable magnet without a pot. This design is also known as a flat pot magnet. These magnetic systems are often fitted with a thread or a bore.

The preferred direction (also known as anisotropy ) refers to the axis along which a magnet achieves its maximum magnetic performance and holding force. It is determined during manufacture by aligning the material in a strong magnetic field so that all the elementary magnets point in the same direction. This can be clearly illustrated by comparing it to the grain of wood: the magnet only operates at full strength in the direction of this ‘magnetic grain’, whilst it can hardly be magnetised at all at right angles to it. In engineering applications, it is crucial to take this direction into account in order to utilise the magnetic system’s maximum efficiency. Isotropic magnets have no preferred direction – they can be magnetised in any direction.

A pulse magnetiser is a device used to magnetise permanent magnets by means of a short, extremely strong magnetic field pulse. A capacitor is charged and then abruptly discharged via a magnetising coil – this generates field strengths of several tesla for a few milliseconds. This is sufficient to fully magnetise even highly coercive materials such as neodymium. Pulse magnetisers also enable complex magnetisation patterns such as multipole or oblique magnetisation and are indispensable in industrial magnet production. BRUGGER has six pulse magnetisers for magnetising AlNiCo, neodymium, samarium and hard ferrite materials up to a diameter of 150 mm.
Magnetisation and demagnetisation are possible with a maximum voltage of up to 3,000 volts.

In radial magnetisation, the direction of magnetisation runs along the radius – from the centre outwards or from the outside inwards. One pole is located on the inside, the other on the outside of the magnet. This type of magnetisation is mainly used in ring and arc magnets for rotors, magnetic couplings and loudspeakers. Unlike diametric magnetisation, where two poles face each other, radial magnetisation produces a uniform magnetic field around the circumference.

Demagnetisation refers to the process by which the direction of magnetisation of a permanent magnet is reversed by a strong counter-field. During this process, the material follows the hysteresis curve. Reversal of magnetisation requires field strengths above the coercive field strength. Repeated reversal of magnetisation results in energy losses in the form of heat – a factor of relevance in alternating fields in motors and transformers.

In the context of magnets,‘tempering’ refers to the process of enhancing magnetic materials through specialised heat treatments. This optimises magnetic properties such as coercive field strength and energy product. For neodymium magnets, tempering takes place after sintering at defined temperatures. Tempering is crucial for achieving the specified grade.

Remanence refers to the magnetic flux density that a permanent magnet retains after full magnetisation in the absence of an external field. It is expressed in tesla (T) or millitesla (mT) and is a key quality characteristic of magnetic materials. The higher the remanence, the stronger the magnetic field at the surface. Neodymium magnets achieve remanence values of 1.0 to 1.5 tesla.

Magnetic resistance – also known as reluctance – describes the resistance of a material or component to magnetic flux. It is the equivalent of electrical resistance in an electrical circuit. Materials with high permeability (such as iron) have low magnetic resistance, whilst air gaps have high magnetic resistance. Minimising magnetic resistance is a key objective in the design of efficient magnetic circuits.

A ring magnet is a permanent magnet in the form of a hollow cylinder with a central bore. It can be magnetised axially (with poles at the end faces), diametrically (with poles on the side faces) or multipolarly. Ring magnets are used in motors, loudspeakers, sensors and clutches. The bore allows them to be mounted on shafts or for cables to be fed through.

The repulsive force describes the force with which two like magnetic poles (north-north or south-south) repel one another. It is the counterpart to the attractive force and follows the same physical laws – as the distance increases, the repulsive force also decreases. The repulsion between magnets is utilised in a targeted manner in engineering: for example, in magnetic bearings for contactless, frictionless support, in magnetic levitation systems or for shock absorption. Care must be taken when handling magnets, as the repulsive force can cause strong magnets to be flung away uncontrollably.

A ring-gap system is a magnetic arrangement in which a ring-shaped air gap is formed between an inner core and an outer yoke. A concentrated, largely homogeneous magnetic field is generated within the ring gap. This design forms the basis for loudspeakers in which the voice coil is driven by the magnetic field within the annular air gap. Other applications include moving-coil actuators, linear drives and sensor technology. An annular air gap system is a special type of magnetic yoke.

Samarium-cobalt magnets are a type of rare-earth magnet and offer high energy products combined with excellent temperature resistance (up to 300–350 °C). They are more corrosion-resistant than neodymium magnets and usually do not require a coating. Their disadvantage is their higher price, due to the cobalt content. SmCo magnets are primarily used in high-temperature applications, the aerospace industry and medical technology.

Magnetic saturation occurs when all the elementary magnets in a material are fully aligned. Any further increase in the external field will then no longer result in any increase in magnetisation. Every ferromagnetic material has a characteristic saturation limit. When designing magnetic circuits, saturation must be taken into account to avoid losses in efficiency.

Shear force is a force that acts parallel to the contact surface of a magnet – that is, pulling sideways rather than vertically. The resulting stress is referred to as shear load. Magnets withstand tensile forces significantly better than shear forces – in rubber-coated magnet systems, the shear force is typically only half to one-fifth of the specified holding force. When designing magnet systems, it is therefore essential to take the direction of the load into account.

Shear force: The force itself acting parallel to the adhesive surface – a physical quantity measured in newtons (N) = ‘How many newtons are acting sideways?’
Shear load: The stress/load situation to which a magnet is subjected by a shear force = ‘The magnet is subjected to a lateral load’

The relationship between shear force and adhesive force is:_Fs =_µh ×_FH. Shear force is equal to the coefficient of static friction multiplied by the adhesive force.
If the coefficient of static friction were equal to 1, the shear force would be equal to the adhesive force.

A short-circuit bar is a piece of soft iron that bridges the poles of a magnet and closes the magnetic circuit. It is used for the storage and transport of certain magnets (AlNiCo) in order to maintain magnetic strength and reduce stray fields.
Functions of the short-circuit bar:

• It protects the magnet: The bar connects the north pole and the south pole. This ensures that the magnetic force remains contained within the circuit, and the magnet lasts significantly longer.
• It shields the magnetic force: When the bridge is fitted, the magnet hardly adheres to anything from the outside. This prevents tools or keys from sticking to it unintentionally during transport.

The short-circuit bracket is particularly indispensable for AlNiCo magnets with low coercive field strength. These brackets are mainly used for older magnets (for example, those used in school physics lessons). Modern, super-strong magnets (such as neodymium magnets) retain their strength on their own. They no longer require this protection. However, a short-circuit bracket could be used here to reduce the stray field, for example to comply with IATA packaging regulations.

The stray field refers to the portion of the magnetic field that does not pass through the intended magnetic circuit. It escapes from the magnet at the sides and does not contribute to the usable holding force. Stray fields can affect sensitive electronics or data storage media. Leakage fields can be minimised through the use of magnetic yokes, pole shoes and an optimised magnetic circuit design.

Soft magnetic materials can be easily magnetised and lose their magnetisation just as easily. They have a low coercive field strength and high permeability. Typical examples include soft iron, electrical steel and ferrite cores. Soft magnetic materials are used for magnetic yokes, transformer cores, relays and shielding – wherever a magnetic field needs to be guided or switched.

The south pole is one of the two magnetic poles of any magnet. Magnetic field lines emerge at the north pole and re-enter the magnet at the south pole. Like poles (south-south or north-north) repel one another, whilst unlike poles (north-south) attract one another. The Earth’s magnetic south pole is geographically located in the north – which is why the north pole of a compass needle points in that direction. Magnetic poles never occur in isolation: if you split a magnet, you create two new complete magnets, each with a north and south pole.
What’s more, one of the meeting rooms at BRUGGER is called ‘South Pole’ ;-)

Temperature resistance indicates the maximum temperature at which a permanent magnet can be used without suffering irreversible losses. It depends on the magnetic material and the grade. Ferrite can withstand temperatures of up to 250 °C, standard neodymium around 80 °C, special grades of neodymium up to 200 °C and SmCo up to 350 °C. The maximum operating temperature is a key selection criterion. Please note the temperature specifications in our product descriptions.

The temperature coefficient indicates the extent to which the magnetic properties of a permanent magnet change with temperature. It is expressed as a percentage per Kelvin (%/K), separately for remanence (α) and coercive field strength (β). Neodymium magnets typically have values of -0.12 %/K for remanence. As the temperature rises, the magnetic force decreases; as the temperature falls, it increases.

The tesla is the SI unit of magnetic flux density (B-field). One tesla is equivalent to one weber per square metre or 10,000 gauss. Strong neodymium magnets achieve surface flux densities of around 0.5 to 0.7 tesla. MRI scanners operate at field strengths of 1.5 to 7 tesla. The unit is named after its inventor, Nikola Tesla.

A teslameter is a precision measuring instrument used to measure magnetic flux density in tesla (T). It typically employs a Hall probe as its measuring head, which converts the magnetic field into a proportional electrical voltage. Teslameters are used in magnet manufacturing for quality assurance, for measuring magnet systems and for testing magnetic shielding. In the US, the term ‘gaussmeter’ is more commonly used, although both devices are functionally identical.

The tipping force describes the force required to detach a magnet from the adhesive surface by means of a rotational movement – for example, by lifting one edge. It is significantly lower than the vertical adhesive force, as lever forces come into play and the contact area is gradually reduced. The actual tilting force depends heavily on how the force is applied to the overall system – the longer the lever arm, the less force is required to detach the magnet. When designing magnetic systems, it is therefore important to consider whether tilting loads may occur.

The pull-off force refers to the force required to pull a magnet vertically away from a steel surface. It is expressed in newtons (N) or kilograms (kg) and is synonymous with the holding force. The pull force (also known as the holding force or attractive force) is measured under standardised conditions – using polished steel and without an air gap. In practice, the actual pull force is usually lower due to surface roughness and air gaps.

Transverse-field magnetisation is another term for diametrical magnetisation. The direction of magnetisation runs perpendicular to the longitudinal axis of a cylindrical or ring-shaped magnet. The north and south poles face each other on the lateral surfaces. This type of magnetisation is frequently used for rotors, sensors and encoders.

In unipolar magnetisation , a magnet has only one north pole and one south pole – the simplest and most common form of magnetisation. In contrast, multipolar magnets have several pairs of poles. The term is used for clarification when the type of magnetisation needs to be specified.

The weber is the SI unit of magnetic flux. One Weber is equivalent to one volt-second or one tesla times one square metre (1 Wb = 1 T·m²). The unit describes the total number of magnetic field lines passing through a surface. It is named after the German physicist Wilhelm Eduard Weber, who made significant contributions to research into electromagnetism.

White regions – also known as magnetic domains – are microscopically small areas within ferromagnetic materials in which all elementary magnets are aligned in parallel. Adjacent regions have different directions of magnetisation and are separated by Bloch walls. When magnetised, the Weiss domains align in the direction of the field – the magnet becomes macroscopically magnetic. The domain model explains why iron can be unmagnetised even though it is ferromagnetic.

A zinc coating provides corrosion protection for neodymium magnets as an alternative to a nickel coating. It offers good protection against oxidation and is visually recognisable by its matt, bluish-silver surface. Zinc-coated magnets are slightly cheaper than nickel-coated ones, but are less abrasion-resistant. They are suitable for applications without heavy mechanical stress. We test our coatings for corrosion resistance using methods such as the salt spray test.