Magnet Materials - Overview

Neodymium Iron Boron
A class of Rare Earth material, available in both sintered and bonded forms. Major characteristics: the most powerful (highest energy product) class of magnet material commercially available today. High Br, relatively high Hc, high BHmax, lower in cost than Samarium Cobalt, temperature sensitive, and susceptible to oxidation. With careful design, some grades will function up to a maximum of about 250°C. Energy product ranges from 10 MGOe to about 53 MGOe. Relative cost index (by weight): 30.

Samarium Cobalt
A class of Rare Earth material, available in both sintered and bonded forms. Major characteristics: High Br, high Hc, relatively high BHmax, higher in cost than Neodymium Iron Boron, highly resistant to oxidation. Most grades function well up to about 300°C. Energy product ranges from 18 MGOe to about 33 MGOe. Relative cost index (by weight): 60.

Ferrite (Ceramic)
Composed of Barium or Strontium Ferrite, these materials exhibit good resistance to demagnetization, and are the lowest cost materials available today. Sintered Ferrite magnets are hard and brittle and are extensively used in consumer products. You are probably familiar with ferrite magnets, often used on the back of refrigerator magnets. Energy product ranges from 1.1 MGOe to about 4.5 MGOe. Relative cost index (by weight): 1.5.

Alnico
An alloy of aluminum, nickel, and cobalt, Alnico magnets have been popular since the 1930s. Alnico magnets are available in cast and sintered forms. Alnico magnets exhibit high Br, but low Hc, and BHmax in the 5 MGOe range. They are the most temperature stable magnets of all the different types, and may be used with no significant losses up to about 500°C. They are relatively easily demagnetized, resisting oxidation well. Energy product ranges from 1.4 MGOe to about 7.5 MGOe. Relative cost index (by weight): 25.

Flexible
A special form of Ferrite or Rare Earth materials, Flexible magnets are manufactured by binding ferrite or Rare Earth magnet powders in a variety of carriers, such as vinyl. The result is a magnet material that can be bent, twisted, coiled, and otherwise easily fabricated. A variety of grades are available, from 0.6 MGOe, to about 1.6 MGOe in the Ferrite based materials and up to about 6 MGOe in the Rare Earth based materials. Relative cost index (by weight, for bonded ferrite): 1.

Relative Cost by Weight	Relative Cost by BHmax
Difficulty to Machine	Maximum Operating Temperature