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Metal Injection Molding (MIM)

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Tooling

MIM tooling is very much like that used in plastic injection molding. These tools can range from simple prototype to multi-cavity production tools.

 


Compounding

We start with a fine metal or ceramic powder (particle size approximately 1-20 microns) and mix this with a proprietary blend of plastics that we call "binders". The powders are incorporated into the fluid binder and pelletized to form a feedstock for an injection molding machine.


Molding

After compounding, the feedstock is injected into a mold to form a "green" part.


Debinding

The binders are removed through thermal processing. In some cases, depending on the application, a solvent bath is used as an initial step.


Sintering

Finally, the parts are put through a high-temperature sintering furnace where the remaining binders are removed. The powder particles fuse together to reach 96-99% of theoretical density.

During this critical step, the parts shrink approximately 20%. We utilize special techniques that result in exceptional metallurgical and dimensional controls, resulting in very repeatable and stable parts.

Depending on the annual volume of your project, the MIM process can be batch or continuous.


Inspection and Secondary Operations

After sintering, the parts are inspected against high quality standards. At this point, additional operations - such as machining, heat treating or plating - may be undertaken to achieve tighter tolerances or enhanced properties.


D2M and Tolerances

Part design greatly impacts process capability. From uneven wall sections to features that need support through sintering, there are specific factors that determine the tolerances possible on a part.

By working with you as early as possible in the MIM process, our sales and engineering staff can help you to match the process’ capability to the tolerances needed to achieve required design function.

Without secondary operations, the general rule of thumb in MIM is that the process is capable of ± 0.3% to ± 0.5% of a given dimension; for example, 1.000 ± 0.005 inches or 25 ± 0.125mm.

Download a free PDF of the MIM Design Guide.