In general, there are four families of magnets available commercially. Factors such as operating temperature, demagnetizing effects, field strength, environmental characteristics, and available space for movement need to be considered before selecting a magnet for a reed switch or reed sensor application. An overview of each of the families of magnets is given below. A list of our standard magnets is available here.
An NdFeB, or Neodymium Iron Boron magnet, is a type of rare earth magnet which is one of the strongest available commercially.
An SmCo or Semarium Cobalt magnet, it a also a type of rare earth magnet which is not as strong as NdFeB magnets but can withstand higher temperatures.
An AlNiCo or Aluminum Nickel Cobalt magnet, is a type of magnet have high coercivity, or resistance to loss of magnetism.
Depending on what a reed switch or reed sensor application demands, we have tabulated the properties of the four types of magnets in increasing order of magnitude. The most important property required should be looked at first and then subsequent ones, to get best results.
|Resistance to Demagnetization||AlNiCo||Ferrite||NdFeB||SmCo|
|Property||CGS Unit||SI Unit||Conversion Factor|
|Magnetic Flux||Maxwell||Weber||1 Weber = 108 Maxwell|
|Magneto-motive Force||Gilbert||Ampere-Turn||1 AT = 1.256 Gilbert|
|Magnetic Flux Density (B)||Gauss||Tesla||1 Tesla = 104 Gauss|
|Magnetic Field Strength (H)||Oersted||Ampere-Turn/Metre||1 AT/m = 0.0125663 Oersted|
|Magnet Performance (BHmax)||MGOe||Kilo-Joules/Metre3||1MGOe = 7.957 KJ/m3|