Metal injection molding offers a manufacturing capability for producing complex shapes in large quantities. The process utilizes fine metal powders (typically less than 20 micrometers) which are custom formulated with a binder (various thermoplastics, waxes, and other materials) into a feedstock which is granulated and then fed into multiple cavities of a conventional injection molding machine. After the “green” component is removed, most of the binder is extracted by thermal or solvent processing and the rest is removed as the component is sintered (solid-state diffused) in a controlled atmosphere furnace. The MIM process is very similar to plastic injection molding and high-pressure die casting, and it can produce much the same shapes and configuration features. However, it is limited to relatively small, highly complex parts that otherwise would require extensive finish machining or assembly operations if made by any other metal forming process.

The advantages of the metal injection molding process lie in its capability to produce mechanical properties nearly equivalent to wrought materials, while being a net-shape process technology with good dimensional tolerance control. Metal injection molded parts offer a nearly unlimited shape and geometric-feature capability, with high production rates through the use of multi-cavity tooling.

The limitation MIM is subject to is one of overall part size, with most components generally not exceeding 250 g.

Typical Markets Using Metal Injection Molded Parts—computer peripherals, medical and dental devices, automotive, firearms, electronic packaging, consumer products

You'll find a great deal more information about the MIM process at mimaweb.org, a dedicated site maintained by the Metal Injection Molding Association.