How Are Neodymium Magnets Made?
Most neodymium magnets are sintered. The neodymium-iron-boron alloy is melted and cast, broken down and milled into a very fine powder, pressed in a strong magnetic field to line up the grains, sintered in a vacuum furnace, ground to size, plated, and finally magnetized with a powerful pulse field and inspected.
The Process, Step by Step
- Melt and CastNd, Fe, B and minor elements melted in a vacuum or inert-gas furnace
- Mill to PowderHydrogen treatment and jet milling make particles a few microns wide
- Press and AlignPowder pressed in a magnetic field so every grain points the same way
- SinterHeated in a vacuum furnace to fuse into a dense, solid block
- MachineDiamond grinding and slicing to final size
- PlateNickel-copper-nickel or another protective coating
- MagnetizeA powerful pulse field sets the north and south poles
- InspectDimensions, coating and magnetic performance checked
Why Magnets Are Shaped Before They’re Magnetized
Sintered NdFeB is hard and brittle, so it’s cut with diamond tools and coolant, never ordinary drills. Doing this before magnetizing keeps the powerful pieces from grabbing tools and chips, and it lets plating cover every surface. That’s also why we don’t recommend drilling or machining finished magnets.
Sintered vs Bonded Magnets
Sintered NdFeB
- Pressed powder fused at high temperature
- Strongest: 33 to 56 MGOe
- Simple shapes: discs, blocks, rings, arcs
- What we sell
Bonded NdFeB
- Powder mixed with a plastic binder, then molded
- Weaker: about 5 to 12 MGOe
- Complex shapes, tight tolerances
- Used inside some motors and sensors
Quality and Compliance
The NdFeB magnets we supply meet EU RoHS and REACH requirements, based on supplier material declarations and, where applicable, third-party lab testing. Read our RoHS compliance statement.