Wet Ball Mill / Attritor

Selection criteria

Final particle size and distribution, milling time, media wear and contamination.

Supply chain

Mainly Chinese machinery makers serving ceramics and magnet plants, with European powder-technology groups at the high end. Particle size here largely sets coercivity, so magnet suppliers should control it per batch.

Buyer FAQ

Ball mill or attritor for ferrite slurry?

Ball mills are simple and robust but need long batch times, often many hours, to reach about 1 µm. Attritors and stirred media mills reach the same size much faster and give a narrower particle-size distribution, at higher media and maintenance cost. Many plants combine coarse ball milling with fine attritor milling.

How is particle size controlled?

Each batch is measured, typically by Fisher sub-sieve sizer (FSSS) for average particle size or by laser diffraction for D50 and D90, with targets around 0.8–1 µm. Milling time is adjusted to hit the target rather than fixed. Ask magnet suppliers to show particle-size records per batch alongside the magnetic test results.

Why does grinding affect magnet quality so much?

Ferrite reaches high coercivity when particles are close to single-domain size, about 1 µm. Under-milled powder lowers Hcj, while over-milling creates fines that hinder alignment, slow filtration and pressing, and raise the risk of cracking. Media wear also adds iron, which shifts the composition unless it is accounted for in the formulation.

Where it is used