Metal injection molding (MIM) is a molding method in which a plasticized mixture of metal powder and its binder is injected into a mold. It is firstly mixing the selected powder with a binder, then granulating the mixture and then injection molding the desired shape. The polymer imparts its viscous flow characteristics to the mix, which aids uniformity in forming, cavity filling and powder filling. After forming, the binder is removed, and the degreased blank is sintered. Some sintered products may also be subjected to further densification, heat treatment or machining. Sintered products not only have the same complex shape and high precision as those obtained by plastic injection molding, but also have physical, chemical and mechanical properties close to forgings. This process technology is suitable for mass production of small, precise, complex three-dimensional shapes and metal parts with special performance requirements.
MIM technology combines the advantages of powder metallurgy and plastic injection molding, breaking through the limitations of traditional metal powder molding technology on product shape, and using plastic injection molding technology to form parts with complex shapes in large quantities and efficiently It has become a near-net-shape technology for modern manufacturing of high-quality precision parts, and has incomparable advantages over conventional powder metallurgy, machining and precision casting. It produces small metal parts with complex shapes like plastic products, usually weighing 0.1-200g; A variety of complex shapes can be formed like plastic products, such as external grooves, external threads, tapered external surfaces, cross-through holes, blind holes, concave tables, key pins, rib plates, surface knurling, etc.; It has good surface finish and high dimensional accuracy, and the usual tolerance is ±0.3%~0.5%; The material is suitable for a wide range, the product has a high density (up to 95% to 99%), and has a uniform structure and excellent performance; With stable product quality and high production efficiency, it can realize automatic, large-scale and large-scale production.
MIM technology is a very important molding technology in the medical device industry. Small medical devices, precision parts, high-precision parts, and high-performance parts are basically produced using MIM technology. It is also very cost-effective for the production of complex precision parts. Common MIM medical instruments include ear parts, hemostatic forceps, laparoscopes, scalpel handles, dental parts, forceps, scissors, orthopedic joint parts, etc. The current trend in the medical industry is minimally invasive surgery and minimally invasive plastic surgery. Many medical device parts that need to be used are produced by MIM technology. Minimally invasive MIM surgical parts have various geometric shapes and complex structures, which require very high dimensions and accuracy. At present, stainless steel, titanium and nickel-titanium alloys are widely used, and MIM technology is used for dental implants.