Bonded Neodymium Iron Boron Magnets
Bonded Neodymium magnets are made of the powerful Nd-Fe-B material mixed into an epoxy binder. The mix is approximately 97 vol% magnet material to 3 vol% epoxy. The manufacturing process involves combining Nd-Fe-B powder with an epoxy binder and compressing the mixture in a press and curing the part in an oven. Since the material is formed by compression bonding, the dimensions typically vary .002″ or better for a given run.
Bonded Nd-Fe-B material is isotropic, so it can be magnetized through any direction, including multi-polar arrangements. Because the material is in an epoxy binder, it can be machined on a mill or lathe. However, the material will not support a thread, so holes cannot be tapped. Bonded Nd-Fe-B material is often used to substantially reduce the size of designs that used ceramic magnet materials. Significant size reductions can be achieved because the material is approximately three times stronger than ceramic magnet material. In addition, since the material is isotropic, it can be magnetized multi-polar, such as a N-S-N-S pattern on the outer diameter of a ring.