Powder metallurgy press molding is the use of gravity to fill the raw material of the powder into the rigid cavity of the mold, and the punch is formed by pressing. The powder pressing die is an indispensable part of the powder metallurgy press forming process, in order to improve the efficiency of press forming. Corresponding requirements have also been placed on powder pressing dies.
First of all, the powder pressing mold cavity should have high hardness and high strength, which can effectively improve the service life of the mold and reduce the production cost. Since the molding cavity is more under the same area, the mold wall of the porous mold is thinner than the common single-hole mold wall. To ensure the service life of the mold, the mold cavity material is required to have high strength.
The multi-cavity of the powder pressing mold determines that the dimensional deviation of each cavity of the mold will accumulate and increase the overall deviation. Therefore, the precision of the matching of the mold and the punch is extremely high in the molding, which requires the basic dimensional accuracy and shape of the mold. The bit tolerance is high and usually needs to be controlled within 0.01mm. For small carbide products, because of the small single weight and high cost of single-piece molding, measures need to be taken to improve the molding efficiency and reduce the molding cost in the design and molding of powder pressing molds.
In addition, the powder pressing mold also has the basic requirements of good finish and low maintenance cost. For single-hole molds, the lower punch can be dismantled for electrical processing and polishing, and the conventional mold preparation process requires reworking of all the molding surfaces of the punch, which reduces maintenance costs. The maintenance cycle has been greatly extended.