In the production of mechanical parts, the consumption and use of powder metallurgy parts are more and more extensive. Compared with other metal part forming processes, the powder metallurgy process has special advantages in reducing production costs and improving part quality by eliminating subsequent processing processes and effectively saving the use of materials.

In addition, with the government's demand for environmental protection and economic development, many iron casting plants have been closed, and the remaining casting plants have been highly automated. The precision castings produced in the old casting plants are either no longer applicable or the price is too high. Even during the transition period, powder metallurgy provides a competitive process for the production of expensive parts from parts and forgings.

The re pressurization process of powder metallurgy parts to make the size of powder metallurgy parts qualified is called finishing, or powder metallurgy shaping. In the process of shaping, the factors that affect the dimensional accuracy of the part are: the radial and longitudinal density distribution of the part, the material strength of the part, the structure of the shaping die, etc.

During powder forming, the friction between powder particles and the friction between powder particles and die wall hinder the filling of the negative mold cavity and affect the uniformity of the density distribution of the compact. If the density distribution of the compact is uneven, it will cause great stress during sintering, making the parts appear uneven shrinkage, distortion, and even cracks.

Powder metallurgy shaping is to put the powder metallurgy sintered body into the mold again for compression, so as to obtain the specified size and shape. The size and shape of the sintered products have changed, which cannot meet the size and shape required by the drawings. In order to correct the size and deformation, it is necessary to put the sintered body into the mold barrel again for shaping. The finished P/M parts will be more regular, the dimensional tolerance will be better, and the surface finish will be improved.