Neodymium NdFeB Block Magnets

Rectangular sintered NdFeB blocks designed to sit inside grate, drawer and hopper housings. They stack in rows and pull ferrous fines out of flowing product.
Ground faces for accurate housing fit
Nickel or epoxy coating

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Products Description

A Neodymium NdFeB Block Magnets for a magnetic separator is a rectangular bar of sintered Neodymium (NdFeB) built to sit inside a housing and pull ferrous fines out of a flowing product. Blocks are the standard element in grates, drawer magnets and hopper traps because they stack in rows, and the field between two rows is where the capture happens.

Tolerance at Each Stage

Separator blocks are bought to a drawing, and the drawing cares about tolerance. The table below shows what each making stage holds, as-sintered, ground, and after plating. A block straight from the press sits around ±0.3 mm; grinding the working faces brings it to ±0.1 mm; plating adds roughly 0.05 mm back. For a separator bar sliding into a machined channel, the ground option is the one that fits without forcing.

Where These Blocks Work

Where these blocks work. Food and plastic lines run them as grate bars over a chute, the product falling past the block face and iron sticking to it. Recycling plants stack blocks in a drawer magnet, pulling rebar and fasteners out of a stream before it reaches a shredder. Quarries and sawmills use the same bar over a conveyor to catch nails and tool fragments before they damage a crusher. In every case the block is not visible; it lives inside a stainless housing, and only the fit of that housing tells you the tolerance mattered.

How Separator Blocks Are Made

Separator blocks are pressed, sintered and then ground on the faces that mate with the housing. Charging is through the thickness so the wide faces carry the field into the product stream. Grade is usually N42 or N45; a hotter line calls for a higher-coercivity grade, which we quote against the actual process temperature rather than a catalogue number. Nickel is the usual coating under a housing, and epoxy is used where the block is handled wet.

How to Specify

If a separator needs neodymium block magnets rather than ferrite bars, send the size, the housing fit and the process temperature, and we will confirm grade, coating and tolerance before quoting. Other sizes are cut and ground to drawing.

FAQ

Q: Does the orientation of a neodymium block magnet affect magnetic separation?

A: Yes. Magnet orientation affects how the magnetic field reaches the material being processed. In a separator assembly, the direction of magnetization and the arrangement of adjacent blocks determine the field pattern at the working surface. Incorrect orientation can reduce the effective capture area or create weaker regions. The complete magnetic circuit should be considered rather than positioning each block independently.

Q: Can a neodymium magnetic separator capture very fine iron powder?

A: Yes, but capture efficiency depends on particle size, magnetic field gradient, distance from the magnetic surface, and product flow. Very fine particles may be carried past the collection surface by fast-moving material or become trapped within the product itself. A strong magnet alone does not guarantee complete removal, so separation performance should be tested under actual operating conditions.

Q: How often should magnetic separators be cleaned?

A: Cleaning frequency depends on the amount of ferrous contamination and the rate at which material passes through the separator. As collected metal builds up, it can interfere with product flow and reduce the exposed collection area. High-contamination processes may require frequent cleaning, while cleaner production lines can use longer intervals. Regular inspection helps establish a suitable cleaning schedule without unnecessary shutdowns.

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