A permanent magnet consists of a ferromagnetic material (only a few) that has been magnetized and creates its own magnetic field. The materials that can be magnetized are also those that are strongly attracted by a magnet, and are called ferromagnetic (or ferrimagnetic); these include iron, nickel, cobalt, some rare earth alloys and some natural minerals such as magnetite. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted by a magnet so intensely that they are commonly considered “magnetic”, all substances respond weakly to a magnetic field, through one of the many types of magnetism.
Ferromagnetic materials can be divided into magnetically “soft” materials (such as annealed iron), on the one hand, which can be magnetized but tend not to remain in such a state, and magnetically “hard” materials, which remain magnetic, on the other. Permanent magnets are made of “hard” ferromagnetic materials that undergo a special treatment in a powerful magnetic field during their manufacture, which aligns their internal microcrystalline structure and makes them very difficult to demagnetize. To demagnetize a magnet of this type, in fact, a certain magnetic field must be applied whose intensity depends on the coercivity of the corresponding material; “hard” materials have high coercivity, while “soft” materials have low coercivity.
Neodymium magnets are made of an alloy of boron, iron and neodymium. This is a strong magnetic alloy; it has a silvery-white colour, is brittle and easily damaged. There are neodymium magnets of different grades: the grade is a code that always starts with the letter N (abbreviation of Neodymium) and is followed by two digits (e.g. N27, N30, N33, N35, N38, N40, N42, N45, N48, N50). This indicates the energy product. A suffix consisting of one or two letters of the alphabet that sometimes follows the number (H, M, SH, EH, UH, etc.) indicates the so-called curie temperature at which the magnets are irreversibly demagnetized. The lower degrees have “less attractive force”, higher degrees have a higher force. There are magnets on the market with grades between N24 and N55, however the grades higher than N52 are not easily available; in the laboratories we have arrived at the creation of magnets of grade N56, while N64 is the theoretical limit.
Neodymium magnets are used to realize those cases where a permanent magnetic source of good intensity is needed.
Neodymium magnets are coated with an antioxidant layer of nickel, zinc or epoxy resin, without which they would “flake” in a short time, thus becoming simple magnetic powder.
Movintech produces and sells magnetic crossbeams for sheet metal with permanent electromagnets and manual neodymium magnets of the latest generation.
High magnetizing power
Long magnetism life
Types from 100KG to 20,000 kg