Permanent magnets

aimants-permanents

Ferrite or ceramic

+ Low cost, good bearing in temperature
– Weak magnetic power

Aluminium-Nickel-Cobalt (AlNiCo)

+ Low cost, high bearing in temperature
– Demagnetization by a weak external field

Samarium-Cobalt (SmCo)

+ Powerful, good bearing in temperature
– Fragile, high cost

Neodymium-Iron-Boron (NdFeB)

+ The most powerful
– Limited temperature, fragile, high cost

Bonded magnet

The bonded magnets come from the mix of plastic compounds with the raw material used for the manufacturing of some types of the magnets mentioned above. The specific properties of the plastics are therefore combined with magnetic characteristics.

Magnetic elastomer

The magnetic elastomers come from the mix of elastomers with the raw material used for the manufacturing of some types of the magnets mentioned above. The specific properties of the elastomers are therefore combined with magnetic characteristics.

Condensed comparison of four main types

( for information only , for your specific needs , please contact us)
tableau

Br : Measure of the induction or of the flux density remaining in a magnet after magnetization. This is called the magnetic persistence. The corresponding unit is the Gauss (Gs) or the Tesla (T). 1 Tesla (T) equals 10.000 Gauss (Gs) or 1 Weber per m².
Hc : With the value of the coercive excitation (Hc), we can know what is the intensity of the opposite magnetic field necessary to completely demagnetize. In other words, the higher its value is, the more the magnet will keep its magnetic capabilities when it is submitted to an opposite direction field. There is a difference between the coercive excitation (bHc) of the flux intensity and the coercive excitation (jHc) of the polarization. If the magnet is plunged in a contrary field of bHc value, there is no more perceptible magnetic flux. The magnet itself is still magnetic, the fields are simply cancelled. This is only in the case the magnet is submitted to a contrary field of value higher than jHc that it will lose its magnetization. The unit is the Oersted (Oe) or the Ampere/meter (A/m). 1 Oersted (Oe) is around 79,577 A/m.

BH max : Term of density of complete energy. The higher the number is, the more powerful the magnet is. This product represents the maximum energy which can be accumulated in a magnet. The maximum energizing product is the surface of the largest rectangle placed in the hysteresis curve of the material. The unit used is the Mega Gauss Oersted (MGOe) or the Kilo Joule by cubic meter (KJ/m3).
T coef Br : The magnetic induction changes according to the temperature. -0.20% means that for a rise in temperature of 100°C, the magnetic induction will be reduced by 20%.
T max : Maximum temperature at which the magnet can operate without being deteriorated (reversible).
T Curie : Curie temperature is the temperature at which the magnet is completely demagnetized. If the magnet is heated between max T max and T Curie, it will be partially restored but not entirely (not reversible).