Sintered NdFeB Production Process-Pulverizing

Sintered NdFeB magnets have a set of scientific production processes. The main production processes include ingredients—melting—pulverizing (hydrogen crushing, jet milling)—forming (pressing, isostatic pressing)—sintering aging— Grinding – wire cutting – electroplating – magnetization – finished product. In a few years, we have come to understand one of the processes – milling.

There are two main processes for milling, hydrogen crushing and jet milling.

1. Hydrogen crushed:
   Hydrogen crushing is also called hydrogen crushing. Rare earths have strong hydrogen absorption properties. Hydrogen atoms will enter the gap between the rare earth-rich grain boundary phase and the intermetallic compound to form a compound of interstitial atoms, so that the gap between the atoms will become larger and the crystal will become larger. Expansion will occur, and the resulting internal stress will cause the grain boundaries of the alloy to crack. There will be a crackling sound in the process of cracking, so it is called “hydrogen fragmentation”.
2. Air-flow mill:
   In the production process, high-pressure and high-purity nitrogen (purity of about 99.995%) of 0.6MPa is usually used as the power source for jet milling. First, the fine powder will be screened, and then the coarser powder will be conducive to collision with each other to make fine powder.