The finest ceramic/metal powder with a grain size ideally of 10-20 µm is mixed with binders (organic compounds, natural waxes, synthetic polymers) in a ratio of approx. 90% metal powder to 10% binder. The binder enables the production of a plasticized mass which is required for shaping. Mixing takes place at an elevated temperature so that the binder becomes malleable and can coat the powder particles. The homogeneous mass prepared in this way is granulated, resulting in the so-called feedstock, which can be further processed directly in an injection molding machine.
Working with the customer, the data required for the injection mold are defined such as the injection point, parting line, required surfaces etc.
Forming through Injection Molding
The feedstock is heated, plasticized and injected under pressure into a negative form (mold) on an injection molding machine, thereby giving it its complex shape. The green part is the result.
Binder expulsion (debinding/dewaxing)
Next, the binder is removed from the green part. This is done either by catalytic debinding, thermal debinding (heating the green parts to melt, break down and/or evaporate the binder) or using solvents (the binder is dissolved by appropriate solvents and removed from the component). The brown part is thus created.
Compacting the material by sintering
The brown parts are sintered in a controlled furnace atmosphere (in a vacuum or a protective gas atmosphere) at high temperatures. The powder particles melt together and acquire the required material properties. The MIM component is created ready for use. The finished piece is approx. 20% smaller than the green part. This measurement factor must be taken into account when designing the mold.
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