MIM is a process of manufacturing that uses a rigid frame, known as a matrix or a mold, to shape liquefied raw material. Similar to the injection molding of polymers, this procedure starts with a metal powder being combined with a wax or polymer binder to create a feedstock. The powder is then suspended in the liquefied polymer or wax and injected into a mold.
Then, heat and pressure are applied to melt away the binder and binding the powder into a solid mass, in a process called ‘sintering’. The mold fills with the metal, which becomes a solid mass. It can be treated like any other metal should annealing, plating, passivating or any other kind of case hardening be called for.
The metal powders used in the process are extremely fine- about four microns in size. It usually consists of iron particles. The pressure used can go up to 2,300 psi. The molds are deliberately designed to gate off, allowing the feedstock to penetrate the chambers in the mold. One mold can produce many identical parts.