Metal Injection Molding (MIM) is similar in many ways to polymer injection molding, but includes several additional steps that are common to powdered metallurgy:

  • Fine metal powder and binder (polymer or wax based) are compounded and extruded into pellets
  • Pellets are fed into an injection molding machine, where they are heated and melted
  • The rotating screw of the injection molding machine shears and compacts the molten metal-binder matrix further liquefying it
  • The injection molding machine injects the metal-binder matrix at high pressure into injection mold tooling, part is cooled and ejected
  • Molded MIM parts, now in their green state are de-bound where ~80% of the binder is removed. Parts are now in their brown state
  • Brown state parts then go into a sintering furnace with high heat and an inert atmosphere where the remaining binder is burned off, and the metal powder diffuses together and densifies
  • Finished parts come out of the sintering furnace at 98% density, or undergo additional operations as required (HIP densification to 99%, secondary operations, heat treatment, finishing, etc)