Rare Earth Magnets and 27 magnet Application

Magnets are interesting fun things. We have magnets in our daily course of life from Toys to heavy industry (magnet application) which require special class of magnets called rare earth magnets.

“The strong permanent magnets made from alloys of rare earth elements are termed as Rare Earth Magnets”.

The ultimate difference between Rare earth magnets and other permanent magnet is that rare earth magnets are made from alloys of rare earth elements while other permanent magnets are ferrite or alnico(magnet appication). Generally, rare earth elements are called so because of two significant reasons. The first naming reason relies on the initially perceived dearth of all rare earth elements. The second one emerges from the fact that it is quite difficult for each rare earth element to extract it purely from its mineral ore bed.

The magnetic field typically produced by rare earth magnets is about 1.4 teslas, while ceramic or ferrite magnets normally evince fields of 0.5 to 1 teslas. The term ‘rare earth’ can be confusing as rare earth metals are not rare but relatively abundant in the earth’s crust. Although they are rarely found in their concentrated formation, they are typically scattered with other elements. The importance of rare earth magnets arises from the fact that there manufacturing, due to the use of powder metallurgy and bonded technology, is relatively easy and efficient in the production of magnets with size as small as 1 mm and as large as 80 mm. disks and rings.

To understand rare earth magnets completely, it is important to know what they are made of and where they come from. In Rare earth class of periodic table, 15 elements are called lanthanides and rest of the two are Scandium and Yttrium.

Rare earth magnets are considered second generation magnets with its derviates expanding to 4th Generation. Manufacturing of these magnets was initiated in late twenty century i.e. 1970. First Rare earth magnet developed was YCo5 by Strnat of U.S Air force

There are many processes for manufacturing rare earth magnets. The most common method is known as Powder Metallurgy. In conventional powder metallurgy manufacturing route, casting of alloy is carried out, Crushing and griniding to achieve single domain particle size is obtained either by Jet Mill or Ball Mill. Third step is to press sample in magnetic field to align particles in easy axis of magnetization. After CIP, samples are sintered for achieving high density and high coercivity.. Ferrite, Samarium Cobalt (SmCo) and neodymium-iron-boron (neo) magnets, all of them are made from powder metallurgy method.

Common applications of Rare Earth Magnets

Since the prices of regular permanent magnets became competitive in the 1990s, neodymium magnets replaced ferrite and alnico magnets in many applications of industry and many of myriad applications in modern technology, requiring powerful magnets. Common applications of rare earth magnets are:

1. Used for head actuators in computer hard drive disks.
2. Used in high-performance AC servo motors.
3. Useful in wind turbine generators.
4. Used in bicycle dynamos.
5. Used in loudspeakers and headphones.
6. Used to erase heads for cheap cassette recorders.
7. Used in fishing reel brakes.
8. Used in automatic door locks.
9. Magnetic bearings and couplings.
10. Used in bench top NMR spectrometers
11. Used in mechanical switches for e-cigarette firing.
12. Used in motors having permanent magnets in cordless tools.
13. Used in traction motors and integral started generators, both in hybrid and electric vehicles.
14. Used in industrialization; for instance maintaining product purity, protection of equipment and quality control.
15. Producing mechanically powdered flashlights, electricity generation in shaking or rotating motion (hand crank powered).
16. Used in capturing fine metallic particles in lubricating oils (crank cases of internal combustion engines), keeping set particles out of circulation, hence rendering them unable to cause grinding wear of moving machine parts.
17. Uses in electric machines (motors) such as:
18. Cordless tools
19. Servo motors
20. Lifting and compressor motors
21. Synchronous motors
22. Spindle and stepper motors
23. Electrical power steering
24. Uses in electric generators for wind turbines (only generators having permanent magnet excitation).
25. Used in turbines that utilizes gears requiring less paramagnetic material per megawatt.
26. Used in retail media case decouplers.
27. Used in industrial processing where powerful neodymium magnets are required to catch foreign bodies and to protect product and processing.