Dry powder pressing die is mostly steel film. During the pressing process, the pressing pressure is mainly consumed by the internal frictional force and the external frictional force. There is internal friction between the powder particles and external friction occurs between the powder particles and the wall of the die, resulting in uneven density distribution of the compact. The density of the part closer to the die is higher when the one-way pressing is used, and the density is higher. Partial density is low. When the height and diameter of the compact are large, the upper and lower densities differ greatly, and a two-way pressing method can be employed. In order to make the compact density distribution more uniform, a stamper with a friction core rod can be used for pressing. When the magnetic material is prepared, the magnetic field is used to increase the magnetic property, that is, an external magnetic field is added on the basis of the ordinary molding, and the pressing direction and the magnetic field direction are parallel and vertical.
There is internal friction between the powder particles of the dry powder pressing die and the external friction between the powder particles and the wall of the die, causing uneven distribution of the density of the compact, which is higher in the density of the portion closer to the stamper when the one-way pressing is used. The farther part is lower in density.
When the height and diameter of the compact are large, the difference between the upper and lower densities is very large, and the same product can be produced by the two-way press. Theoretically, the required pressing energy is almost the same, but each has its own characteristics. The mechanical press has a high productivity of 1.5 to 5 times that of a hydraulic press.www.yxhgmould.com