How to Magnetize and Demagnetize Permanent Magnets

Magnet magnetization is the step of magnetizing a processed magnet, and magnet demagnetization is the step of demagnetizing a magnet with magnetic properties, which are two different processes, and the methods of magnetization and demagnetization are described below.

Magnetize the magnet;

Magnetizing permanent magnets usually involves the use of DC magnetizers or capacitor discharge magnetizers to apply a sufficient magnetic field around the magnet to bring it to technical saturation.

Magnet magnetizing equipment

It is first necessary to select the appropriate magnetizing equipment according to the material of the permanent magnet and the required magnetizing strength, and then determine the direction in which the magnetization is required. Then the permanent magnet is placed in the magnetic field area of the magnetizer, and the permanent magnet is magnetized by applying a strong external magnetic field, giving the magnet a short time to magnetize the magnet can be completed.

Demagnetization of magnets

There are various cases of demagnetization of magnets, such as wrong plating, wrong direction of magnetization, customer does not need magnetized delivery and many other cases.

Magnet demagnetization generally has heating high temperature demagnetization, demagnetization machine demagnetization, vibration demagnetization. Heating is to heat the permanent magnet to its Curie temperature (the temperature at which the material loses its magnetism) or above, and then slowly cool it down, which can make the permanent magnet lose its magnetism. Demagnetizing machine is used to remove the magnet or other ferromagnetic materials residual magnetism of special equipment, mainly pulse demagnetizing machine, AC demagnetizing machine, the use of demagnetizing machine should not be used continuously for a long time, in order to avoid overheating damage to the coil.

In the experiments I conducted, the temperature resistance of the NdFeB magnets used was 100°C. When heated to that temperature, the magnetic force began to show a significant decline, and at 150°C, the rate of magnetic force decline accelerated significantly, and it took only 20 minutes for the magnetic force to degrade almost completely. For NdFeB magnets that have lost their magnetic properties, although they can be re-magnetized, the magnetic force can only be restored to about 50% of its original state, and the surface will appear blackened and oxidized.

The choice of magnetizing and demagnetizing methods depends on the material, size, shape and specific application requirements of the permanent magnet. For specialized magnetic material handling, specialized equipment and processes are often recommended.

Magnetization and demagnetization related articles;

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Do neodymium magnets demagnetise at transient high temperatures?