Metal injection molding (MIM) is a high-tech technology that combines traditional powder metallurgy technology and plastic injection molding technology. MIM began in the late 1970s. In the past, due to the lack of suitable powder or the high price of raw materials, incomplete knowledge, immature technology, people’s understanding and market acceptance, it takes time, the production (including mold manufacturing) cycle is too long, insufficient investment, etc. Its development and application are relatively slow. In order to solve the difficulties of MIM technology, Japan, Germany, etc. subsequently joined in the development and research of MIM. With the continuous deepening of MIM scientific research and the development of new binders, powdering technology and degreasing technology, industrialization has been achieved by the early 1990s. After more than 20 years of hard work, MIM has now become a promising new near-net forming technology in the international powder metallurgy field, and is known as the most popular forming technology for metal parts in the world.
The basic process of MIM is to first select metal powder and binder that meet MIM requirements, and then use an appropriate method to mix the powder and binder into a uniform injection molding feed at a certain temperature. After granulation, it is injected Injection molding is performed on a molding machine, and the obtained molded blank is degreased and then sintered and densified into the final product. The MIM process includes eight important links such as product design, mold design, quality inspection, mixing, injection, degreasing, and secondary processing. MIM combines the advantages of powder metallurgy and injection molding, breaking through traditional metal powder molding. Process limitations on product shape. MIM utilizes the technical characteristics of metal powders to sinter to produce dense mechanical parts with good mechanical properties and surface quality; it uses plastic injection molding technology to produce parts with complex shapes in large quantities and efficiently.
The advantages of MIM technology are mainly reflected in the following aspects:
1) It can produce parts with very complex shapes;
2) The degree of densification of sintering is high, and its performance is comparable to that of forged materials;
3) It can maximize the production of final shapes parts without subsequent machining or with minimal machining;
4) High material utilization rate, suitable for mass production;
5) Equipment investment is small, and the entire process can be automatically controlled, resulting in high production efficiency.