Magnetisation types and magnet systems

Introduction to magnet systems

As opposed to permanent magnets, magnet systems are made up of permanent magnets and pieces of iron. The use of iron pieces has quite a few benefits. The most important of them include:

1. Iron allows a higher magnetic induction than permanent magnetic materials.
2. As opposed to permanent magnet material, iron can be machined more easily.
3. In iron, the lines of force can be steered and focused.
4. The magnetic material is easier to utilize.
5. Magnetic constructions are simpler and more affordable.

There is such a large number of different magnet systems, because each particular use calls for a custom designed magnet system to best suit the purpose. Here, we are limiting our description to adhesive magnet systems that are not switchable.

Production

Adhesive magnet systems are available as ready made. However, you can also produce them yourself. In their construction, not only mechanical conditions must be observed, but also conditions relevant to magnetism.

Physical properties

The physical properties depend on the materials used for producing the adhesive magnet systems. With respect to bonded systems especially, consideration must be given to the properties of the adhesives.

Magnetic properties

The magnetic properties of adhesive magnet systems depend on the magnetic material used.

Stability

The stability depends on the magnetic materials used.

What must also be considered is that all magnet systems using magnets that have a kink in the demagnetization curve cannot be removed without incurring great loss in the magnetic force, which can only be reversed by magnetizing the magnets again after reassembly.

Magnetizing

The saturation field strength depends on the magnetic materials used. However, what must also be taken into account are the iron conductive pieces, which, depending on the circumstances, may short circuit a large portion of the available magnetic flux. Magnet systems made of AlNiCo must almost always be magnetized after assembly, whereas hard ferrites only in part and systems with magnetic materials made of rare earth almost hardly ever.

Machining

Machining the iron parts is no problem. However it is critical to make sure not to fall below the minimum number of cross sections required for the magnetic flux (for example by overturning pot magnets), because this would otherwise adversely affect the performance of the magnet systems.

Assembly

Assembly is not particularly problematic for AlNiCo and hard ferrite, but when it comes to AlNiCo, what must be considered during assembly is that the two magnetic poles of the iron parts are not short-circuited. Magnets made of rare earth, such as samarium cobalt or neodymium, are for the most part assembled with magnetized magnets. They feature very high forces and we recommend working with the appropriate devices, both when performing separation processes as well as during assembly. With respect to samarium cobalt materials, it is important to account for their high degree of brittleness.