Steps of MIM processing
MIM processing requires 3 steps:
(1) A mixture of powdered metal and thermoplastic (or other binder) is injected into the mold cavity under heating and pressure (similar to thermoplastic injection molding).
(2) The binder is removed by heating or melting, leaving only metal powder.
(3) The metal powder is sintered, and the sintering temperature should be lower than the melting point of the metal, but enough to combine the metal powder into solid metal (the actual density of solid metal is greater than 96%).
MIM can be used to process cemented carbide, other metals and metal alloys (including precious metals). Since the particle size of metal materials used in MIM processing is much smaller than that used in other POWDER metallurgy processes, it is more appropriate to call it metal "micro powder", whose fineness is similar to that of gold pigment powder (particle size less than 20μm).