How are Rare Earth Magnets made?
Rare Earth Magnets are produced by a process called powder metallurgy with a chemical arrangement of Nd, Fe, B and other small elements. NdFeB neodymium magnets are the Rare Earth Magnet with the largest magnetic execution and compelling force in the world.
The Production of Rare Earth Magnets
Rare Earth Magnets are produced in several ways, some of which are the following:
a) Vacuum Melting – A combination of Neodymium, iron, iron-boron, dysprosium and other components such as copper, gallium, aluminum etc which are stirred and melted together. In most cases, the melting process is repeated several times in order to reach the performance required by the magnets.
b) Crushing – The bars produced in the vacuum melting process are smashed into coarse powder.
c) Jet Melting – The coarse powder is grinded further into small particles. This way of production has proven to be the most effective.
d) Pressing – Pressing the powder to make block magnets, using two possible pressing methods, transverse and axial. Using the two different methods depends on the different applications.
e) Vacuum Sintering – The now compacted magnets are heated at the temperature of 10000C for many hours until they are solidified and even more compacted. In some instances further heat treatments are required in order to stabilize the magnets.
f) Machining – A process used to clean up grind from the surface left from the shrinkage and distortion occurring during sintering. Small sections are cut off from a large block which enables the manufacturer to reach the tolerance and different shapes needed and
g) Surface Treatment – Different surface treatments can be used on the end result product which provides different kinds of surface finishing, looks and corrosion resistance which are required in different environments. There are additional methods to produce Rare Earth Magnets, however, the ones mentioned above are the ones most commonly used.