The History

The technology of powder injection molding was invented more than half a century ago. However, the application of this technology to injection molding metals started as recent as early 80s. In fact the successful commercial manufacturing employing powder injection molding technology only began some ten years ago.

Integrated with the shaping capability of plastic injection molding and the material flexibility of the conventional powder metallurgy, the hybrid technology. Metal Injection Molding (MIM) moulds metal or ceramic powders just like plastic. MIM is now a preferred manufacturing method for the mass production of small size, intricate geometry components of varieties of materials, achieving close to 98% of the wrought material properties at much reduced cost in comparison with conventional machining, investment casting or precision stamping.

The Technology

MIM starts with the material selection and preparation. Blending and compounding the appropriate combinations of metal powders and plastic binders, an injection mouldable feedstock is produced. An oversized metal die set is used to produce so-called Green Parts using a normal injection molding machine, just like molding Engineering plastic parts. These Green parts are subjected to a binder removal process by either washing away or burning off or their combinations to produce so-called Brown Parts. A sintering process employing advanced control over temperature and atmosphere ensures the right material composition, physical properties and correct geometry to be imparted to the parts. These parts undergo 15 to 25% of linear dimensional shrinkage during high temperature consolidation and reach at least 96% of the theoretical density. A simple coining/sizing operation is commonly practiced in industry to ensure parts meeting extremely high precision blue print specifications.

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