Magnet Information

• Ferrous (Steel, Iron): Your run of the mill common 'permanent' magnet.
• NdFeB (Neodymium-Iron-Boron): The most powerful 'rare-earth' permanent magnet composition known to mankind.  This formulation is relatively modern, and first became commercially available  in 1984. NdFeB magnets are the strongest commercially available formula. They are very brittle, hard to machine, and sensitive to corrosion and high temperatures. About 4-5 times the strength of ceramic magnets.
• Ferrite (Ceramic): Also known as 'hard ceramic' magnets, this material is made from Strontium or Barium Ferrite. It was developed in the 1960s as a low-cost and more powerful alternative to AlNiCo and steel magnets.  Less expensive than NdFeB magnets, but still very powerful and resistant to  demagnetization.
• AlNiCo (Aluminum-Nickel-Cobalt): Medium strength and excellent machinability. Developed in the 1940s and still in use today. They  perform much better than plain steel, but are much weaker in strength than NdFeB magnets, and must be carefully stored since they are prone to demagnetization.  Contact with a NdFeB magnet can easily reverse or destroy the field of an AlNiCo magnet.