Sintering technology was born more than 1,000 years ago and has been used in many industries, from the well-known ceramic industry to the powder injection molding industry.
The sintering process is mainly divided into three stages
Initial stage, intermediate stage and final stage
After the raw embryos injected by the injection machine are subjected to acid removal, most of the binder (POM) is removed, and a small amount of high-temperature binder is still retained to maintain the shape of the product. These residual high-temperature binders are removed by heating to 600 degrees in the sintering furnace for a decomposition reaction. This stage is different from acid degreasing, which is called thermal degreasing stage, also known as pre-sintering.
Initial stage: The metal powder particles in the fully degreased embryo form a sintering neck from the contact point and grow up
Intermediate stage: the sintering neck grows, the gap between the metal powder particles gradually decreases, forming a pore network connected by grain boundaries
Final stage: The pores between the particles eventually become closed and independent pores, and the product is formed
After the sintering stage of the product, because the gap between the particles is greatly reduced, the product volume shrinks and the strength is improved. The advantages of powder injection molding are reflected in this: because the raw embryo of the product is injection-molded by uniformly mixing metal powder and binder in a certain proportion, the composition of each part on the green embryo is relatively uniform, so that it can be sintered during sintering. It is guaranteed that the product can shrink isotropically in all directions, and the shape and dimensional accuracy of the product are well guaranteed, which is also a feature of MIM.
With the innovation and progress of technology, material processing technology is developing in the direction of high performance, low cost, short process and near-finish molding, and many new preparation technologies integrating design, preparation and processing have emerged, such as metal Powder injection molding technology
