There are three main methods of pressing the powder – axial and transverse pressing. Die pressing requires tooling to make a cavity that is slightly larger than the required shape (because sintering causes shrinkage of the magnet). The Neodymium powder enters the die cavity from the hopper and is then compacted in the presence of an externally applied magnetic field. The external field is either applied parallel to the compacting force (this axial pressing is not so common) or perpendicular to the direction of compaction (this is called transverse pressing). Transverse pressing gives higher magnetic properties for the NdFeB.
A third method of pressing is isostatic pressing. The NdFeB powder is put into a rubber mould and is put into a large fluid filled container which then has the pressure of the fluid increased. Again an external magnetizing field is present but the NdFeB powder is compacted from all sides. Isostatic pressing gives the best possible magnetic performance for Neodymium Iron Boron. The methods employed vary depending on the grade of "Neo" required and are decided by the manufacturer.
