Neodymium or NdFeB

By : Josevan Setiaputra Hong

A neodymium magnet (also known as NdFeB, NIB or Neo magnet), the most widely used type of rare-earth magnet, is a permanent magnet made from an alloy of neodymium, iron and boron to form the Nd₂Fe₁₄B tetragonal crystalline structure. Neodymium magnets are the strongest type of permanent magnet commercially available.

Neodymium is the second most abundant of the rare-earth elements (after cerium) an is almost as abundant as copper. It is found in minerals that include all lanthanide minerals, such as monazite and bastnasite. The main areas are Brazil, China, USA, India, Sri Lanka and Australia. Reserves of neodymium are estimated to be 8 million tonnes, world production of neodymium oxide is about 7.000 tonnes a year.

Due to difference in the manufacturing process, Neodymium magnets are separated into two categories, named sintered NdFeB magnets and bonded NdFeB magnets.

Sintered Nd-magnets are prepared by the raw materials being melted in a furnace, cast into a mold and cooled to form ingots. The ingots are pulverized and milled; the powder is then sintered into dense blocks. The blocks are then heat-treated, cut to shape, surface treated and magnetized.

Bonded Nd-magnets are prepared by melt spinning a thin ribbon of the NdFeB alloy. his ribbon is then pulverized into particles, mixed with a polymer, and either compression– or injection-molded into bonded magnets. Bonded magnets offer less flux intensity than sintered magnets, but can be net-shape formed into intricately shaped parts, as is typical with Halbach arrays or arcs, trapezoids and other shapes and assemblies.

Neodymium magnets have replaced alnico and ferrite magnets in many of the myriad applications in modern technology where strong permanent magnets are required, because their greater strength allows the use of smaller, lighter magnets for a given application. Neodymium is one of the several metals in alloys commonly used in lighter flints. Some example are :

• Head actuators for computer hard disks
• Erase heads for cheap cassette recorders
• Mechanical e-cigarettefiring switches
• Locks for doors
• Loud speaker headphones
• Mobile phone speakers, taptic feedback and auto focus actuators
• Magnetic bearing sand couplings
• Benchtop NMR spectrometers
• Electric motors:
  • Cordless tools
  • Servomotors
  • Lifting and compressor motors
  • Synchronous motors
  • Spindle and stepper motors
  • Electrical power steering
  • Drive motors for hybrid and electric vehicles.
  • Actuators
• Electric generators for wind turbines (only those with permanent magnet excitation)
  • direct-drive wind turbines require c. 600 kg (1,300 lb) of PM material per megawatt
  • turbines using gears require less PM material per megawatt
• Alignment of Nanocellulosechiral nematic suspensions to fabricate cellulose nanocrystals films with tuneable specular and off-specular optical response
• Voice Coil
• Retail Media Case Decouplers