Magnetism has long been underrated compared to its partner electricity. Magnetism forms the heart of nearly every electronic device that we see these days. Be it the good old electric motor or the transformer.
Televisions, CRT monitors, DC Motors, various measuring instruments, etc make use of permanent magnets in their working and electromagnetism seems to be virtually everywhere. While permanent magnets have typically been thought of made of iron, recent years have seen the emergence of permanent magnets made of alloys of rare earth metals.
Rare earth magnets are much stronger than typical magnets made of ferrite or alnico, giving them a huge area of potential applications
Widening the field of Rare Earth Magnets
The name ‘rare earth magnets’ misleads many into thinking that they are very rare and precious, but in fact ‘rare earth’ refers to a class of metals, namely the lanthanide series metals, not particularly rare in the earth’s crust. Rare earth metals are ferromagnetic, that is, they can be magnetized, like Iron. But in normal conditions their magnetism manifests in very low temperatures.
As a comparison, the magnetic field generated by rare earth magnets is around 1.4 to 1.5 Tesla (unit of magnetic field) while that generated by typical ferrite or alnico magnets is around 0.5 to 1 Tesla. There are two major kinds of rare earth magnets currently prevalent.
Samarium-Cobalt was the earlier standard, somewhat more expensive and less powerful compared to Neodymium magnets now used. Neodymium is very powerful and affordable. The high magnetic field strength and magnetic anisotropy of rare earth magnets, along with their affordable price, enables them to have widespread application. Some common applications include:
– Hard disk drives in Computers
– Headphones and speakers
– Bicycle dynamos
– Self-powered flashlights, that use a rare earth magnet to generate electricity for operating the light
– Permanent magnet motors
– Security systems
– Mag-lev trains
– Industrial uses like magnetic separation, retrieval, etc
– In miniatures, toys, etc.
Rare Earth Magnets – Beware!
With great power comes the ability to be dangerous, and it is the same with rare earth magnets.
Rare earth magnets have hazards unseen in typical magnets. Larger magnets are capable of causing serious injuries, even broken bones, if some limb or part of the body gets stuck in between 2 magnets or a magnet and a metal surface.
Also, these magnets should be kept well out of the reach of small children. If ingested, they may be very dangerous, even fatal. Apart from the danger of physical injury, rare earth magnets should also be kept at a safe distance (namely 12 cm) from devices using magnetic storage, like hard disks, credit cards, etc.