Fresh from the jet mill, the powder is magnetically random — every tiny crystal points its own way. Press it into a magnet like that and you get a lump of metal with almost no magnetic strength. The fix is one of the cleverest steps in the whole process: press the powder inside a strong magnetic field.
How it works, in one sentence
The powder is poured into a mold, a powerful electromagnet switches on, and every particle rotates to line up like a team of tiny compass needles — then a press squeezes them into a solid block while the field holds them in place.
Why the field matters
Every NdFeB crystal has one easy direction in which it prefers to be magnetized — think of a tiny arrow. The field turns all the arrows the same way, and the better they align, the stronger the finished magnet. This single step decides which face of the magnet becomes north.
The fight between field and pressure
Here is the tricky part: pressure packs the powder densely, but it also tends to knock the particles out of alignment — like trying to keep pencils pointing the same way while pushing them into a box. Smart production methods press from a direction that does not fight the field, or use pressure from all sides, which packs the powder tight without rotating the particles.
Why it is worth the effort
The result is a green body — a fragile pressed block, about two-thirds as dense as the final magnet — with all its tiny arrows pointing the same way. Everything from here on must preserve that alignment.
The green body now goes into the furnace for sintering, where heat welds the powder into a solid magnet.
Read on: sintering → · how NdFeB is made →