From development to production
Things to know
Temperature and adhesive force
Please note the respective temperature specifications for the maximum operating temperature of our magnet systems. In general, the holding force of the systems decreases with increasing temperature for every magnet alloy. The max. operating temperature stated in the catalogue indicates the temperature up to which the systems can be used without being damaged. If this limit is exceeded, this will affect plastics, adhesives and/or the magnetic force.
The following diagrams show the dependence of the holding force on the temperature, as well as on other influencing factors such as air gap and counter anchor:
Schematic representation of the dependence of adhesive force and temperature
Schematic representation of the dependence of adhesive force and air gap
Schematic representation of the dependence of the adhesive force on the material of the counter anchor
General safety data sheet
The safety data sheet describes products with regard to safety requirements. The information does not have the meaning of an assurance of properties.
The steel parts are galvanised as standard and then blue passivated. The magnets are bright nickel-plated.
All magnet systems supplied by us are always manufactured with the same magnetisation, i.e. the arrangement of the poles on the holding surface is always the same for each alloy.
It is essential to observe the following when handling magnets:
The type of magnetisation depends on the desired application, the design and the material of the magnets used. For example, different magnetic fields and holding forces can be achieved with different types of magnetisation while the design is otherwise the same. The raw magnet used also plays a role. If it is an anisotropic specimen, the first four of the magnetisation types mentioned here generally come into play. In the case of an isotropic magnet, the last two types of magnetisation are generally used.
Axially magnetised, anisotropic
Axial sector magnetised, anisotropic
Bipolar magnetised, anisotropic
Diametrically magnetised, anisotropic
Multipole surface magnetised, isotropic
Radially magnetised, isotropic
Unequal in structure with respect to the spatial directions. For magnets, this means that a strong magnetic field is applied during production and thus a device of "elementary magnets" is achieved. During subsequent magnetisation with the field direction in the device axis, better results are obtained for the magnetic values than in other spatial directions.
Identical in structure with respect to the spatial directions. For magnets, this means that none of the spatial directions is preferred when magnetising in the direction of a particular axis.
Orientation of the magnetic crystals in a certain direction.
A permanent magnet is a magnet that exhibits and maintains a static magnetic field.
The operating temperature indicates the temperature up to which magnets can be used. In general, the holding force of magnet systems decreases with higher temperatures. Strong heating (temperature rises above the so-called Curie temperature) leads to irreversible demagnetisation.
Space or distance between two opposing surfaces of a magnet or magnet system and again of a magnet or magnet system or a magnetisable object. The space between the surfaces must consist of non-magnetisable material.
Magnetism is a physical phenomenon, a sub-area of electromagnetism as one of the four basic forces of physics. Magnetism is described with the aid of the magnetic field H and the magnetic flux density B. Magnetism is caused by moving electrical charges or by magnetic (orbital) torques and intrinsic torques (spin) of electrons. Magnetism manifests itself in a force mediated by the magnetic field, emanating from magnetic objects (such as permanent magnets) or acting on them (such as iron).
A magnetic field aligns the elementary magnetic particles. This makes the object magnetic.
Composite of a magnet with other components made of metal and/or plastic.
Rare earths (SE)
belong to the metals, or rather to the 14 chemical elements in the periodic table that follow lanthanum, the lanthanides, as well as scandium and yttrium. Neodymium belongs to the light rare earths (cerium group).
The second quadrant of the hysteresis of permanent magnetic materials shows the demagnetisation curves shown here. These show the differences between neodymium-iron-boron, samarium-cobalt, aluminium-nickel-cobalt and hard ferrite magnets, which we use in our magnet systems.
The remanence B is the measure of the magnetic induction that remains in the magnet after magnetisation.
The coercivity Hc describes the magnetic field strength necessary to make the magnetic induction in the magnet disappear. This is what happens when a permanent magnet is introduced into an inversely polarised magnetic field with a coercive field strength Hc.
Alloy of neodymium, iron and boron with the composition Nd2Fe14B.
NdFeB magnets have a hardness of 560-580 HV and are less brittle than alloys of HF and SmCo. The material can be machined with diamond tools and wire and sink erosion. Due to the strong oxidation in the raw state, they are mainly offered nickel-plated or zinc-plated. NdFeB magnets have a very high energy density, so 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)
Alloy of the rare earth metal samarium (Sm) with the metal cobalt (Co).
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 with diamond tools and wire and sinker EDM. Due to the high cobalt content, they are more expensive than other magnet materials. SmCo magnets oxidise only slightly and have good chemical resistance. Due 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*. Small cracks in the magnet material do not affect the holding force.
Alloys of aluminium, iron, nickel, copper and cobalt. Permanent magnets are made from these by casting techniques or sintering.
These magnets have a hardness of 510 HV and can be machined with diamond tools (grinding, drilling), wire and sink erosion, water jet cutting, hard turning and hard milling. Due to their magnetic properties, magnets made of AlNiCo must have a long length in the direction of magnetisation in order to have good resistance to demagnetisation as open magnets. AlNiCo magnets are very temperature resistant and can be used in ranges from -270°C to + 450°C*.
Hard magnetic ferrites (HF)
Are made from iron oxide and strontium carbonate.
Strontium ferrites Composition: SrFe12O19
These magnets have a hardness of 480-580 HV and can be machined with diamond tools, as well as 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 cheap.
Chipping on sharp edges of ferrites is permitted insofar as the original shape of the magnet and thus its function are still given. If 100% flawless edges are required, this must be explicitly stated. Minor cracks in the magnet material have no influence on the holding force.
Magnets made of HF can be isotropic (no preferred direction of the elementary particles ->lower adhesive force) or anisotropic (elementary particles are preferentially directed ->higher adhesive 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 with diamond tools. Furthermore, HF is insensitive to oxidation and weathering and has good chemical resistance.
* However, the maximum operating temperature varies and depends decisively on the actual alloy, the area of application, the connected materials, as well as the geometry of the magnet. For precise information on the temperature range of your magnet system, please refer to our product catalogue or contact us personally.
Before the discovery of the connection between magnetism and electricity, magnetic phenomena were only observable and usable through natural magnetic iron stones. An important application of this was the compass, the principle of which was already known in pre-Christian China and in Greek antiquity. Magnetic iron stones were named after the landscape of Magnesia in Greece, where they were found early on. The removal of iron points from the body by magnetic forces was also already practised and described in ancient Indian medicine.
In the 13th century, the first records were made in Europe about the magnetisation of compass needles and other important findings about magnetism, such as knowledge of the magnetic properties of the earth's sphere.
In the following period, systematic experiments made it possible to create the first "artificial" magnets. For example, the lines of force at the poles of magnetic stones were concentrated with small iron caps, or magnetic steel needles were bundled by binding them together. Even in the 18th century, magnetism was still unexplained but fascinating. The discovery and use of the magnetic properties of rare earth combinations such as NdFeB, SmCo, AlniCo have led to enormous improvements in performance in recent years.
Some of our magnet systems are a combination of a permanent magnet core together with an iron housing. We can achieve increased holding forces by using different possibilities when combining them.
You can see the possibilities in the following illustration. The holding force of the magnetic core is the reference for the following possibilities:
Magnetic core with iron back
Magnetic core with iron return and centre pole
U-shaped iron magnetic core
Magnetic core in iron round housing (flat pot magnet)
Ring magnet in iron housing with
Magnetic rod made of AlNiCo in iron round housing (pot system)
Magnetic core with pole shoes