Magnetic Terms

 

Energy product (WxH)max

The maximum energy product of the flux density B and field strength H is the most important quality of a magnetic material. The higher the energy product, the greater the magnetic energy. The higher the (WxH)max value of a magnetic material, the lower the magnetic volume required for a certain task with otherwise identical ratios.

Coercivity Hc

Coercivity is the field force necessary to eliminate magnetization. The higher the value, the more resistant the magnetiza- tion. A distinction is made between HcB and HcJ.

Remanence (Br)

Remanence is the residual magnetization of a magnetic material magnetized up to saturation in a closed circle. Remanence is stated in Gauss (G), Tesla (T) or Millitesla (mT).

Operating temperature

The operating temperature is the highest temperature to which a magnet can be exposed without suffering a permanent loss of its magnetic power. It is an approximate value because there is dependence to the dimensioning. There are factors, e.g. mechanical or chemical stress, which may further limit the maximum operating temperature.

Curie temperature

If the Curie temperature is reached, the magnetic material loses its magnetism.

 

magnetic-terms

 

Magnetic materials features table:

 

Magnetic Materials
Magnetic material Energy- product Remanence Coercivity Temperature- coefficient Operation temperature Curie- temperature Density
Br
(B x H) max mT HCB HCJ per 1 °C °C °C g/cm3
kJ/m3   kA/m kA/m        
Barium ferrite 7.2 – 7.6 210 – 220 130 – 135 220 -0.20% 250 450 4.9
isotropic
Barium ferrite 28.9 – 29.5 390 – 400 145 – 160 150 – 165 -0.20% 250 450 4.9
anisotropic
Strontium ferrite 24.5 – 25.5 350 – 370 210 – 245 220 – 255 -0.20% 250 450 4.9
anisotropic
AINiCo 500 35 – 36 1,120 – 1,160 47 – 49 47 – 49 -0.02% 400 890 7.3
Samarium- 140 – 150 850 – 890 620 – 670 1,100 – 1,200 -0.04% 250 720 8.3
Cobalt SM 18
SmCo5
Samarium- 190 – 205 1,000 – 1,050 680 – 750 1,195 – 1,500 -0.03% 250 800 8.3
Cobalt SM24
Sm2Co17
Neodymium- 260 – 285 1,180 – 1,220 860 – 915 >= 955 -0.13% 80 310 7.4
Iron-Boron
NdFeB 35*

 

Values determined at a temperature of 20 °C.
*Qualities available with an operating temperature of up to 220 °C.