Metal Injection Molding (MIM) is a growth technology for manufacturing complex, high volume ferrous parts. Metal powders are mixed with thermoplastic binders to form a homogeneous mixture, with approximately 65% volume metal powder and 35% volume plastic. This mixture is then molded at relatively low temperatures and pressures in conventional plastic injection molding machines. The molds are similar to those used in plastic injection molding, with slides and multi-cavity configurations possible.
The molded "unfinished parts" are then thermally processed in two steps.
First, the binder is removed by evaporation in an operation called debinding. Second, the part is sintered (heated to a temperature near the alloy melting point) in a dry hydrogen atmosphere, which densifies the part isotropically. The complex shape of the original molded part is retained throughout this process, and close tolerances can be achieved. Only minor, if any, machining is required as a secondary operation. Like other volume production methods, MIM conserves material and time.
