Metal injection molding services use a powder metallurgy process to manufacture metal parts. Although metal injection molding uses metal powder, MIM is very different from conventional powder metal processes.
First, metal injection molding services use metal powders that are 10 – 100 times smaller than those used by standard powder metal services.
Second, the end product of metal injection molding (MIM) has a much higher density (greater than 95% theoretical density).
Finally, unlike powder metal services, metal injection molding (MIM) services can produce parts that can be case hardened, through hardened, painted, drilled and tapped.
Metal injection molding services provide many of the same features and benefits of plastic molding services and rubber molding services; however, MIM services but produce a much stronger end-product.
Metal injection molding services can also provide a substantial cost savings over conventional metal machining services. In addition to their higher densities, MIM parts have mechanical properties approaching those of forged or machined components. Parts produced by metal injection molding services include surgical tools, automotive locks and actuators, firearm components, computer hard disk drives, and electrical connectors.
Metal injection molding (MIM) services perform a process with five basic steps: mixing, injection molding, de-binding, sintering, and part finishing.
- In the mixing step, metallic powders which are selected for their specific abilities (e.g., impact strength, high and low temperature characteristics, wear resistance characteristics, machinability, and hardness) are mixed, often with a binding agent. By mixing these powders together, MIM services can create a composite with the strengths and benefits of all the constituent metals, while offsetting their independent weaknesses. Once the powders are mixed, a feedstock is produced.
- Next, metal injection molding (MIM) services inject this feedstock into molds in the same way as plastic injection molding or rubber injection molding. The part that emerges from the injection molding stage is referred to as a green part.
- During the de-binding stage, metal injection molding (MIM) services immerse the green part in a water bath to remove the binder, which has entered into the part matrix. During cross-linking, the de-bound green part is exposed to ultraviolet light which thermosets the binding agents used with the metal powders.
- Once this has been completed, the part is placed into a furnace and heated to over 2000˚ F. This process, called sintering, fuses the metal parts into a solid shape.
- Finally, metal injection molding (MIM) services sent the sintered piece to a finished stage where burrs and surface imperfections are removed and the finished part can be shipped.