The Metal Injection Moulding(MIM) combines the advantages of the large degree of design freedom that comes with plastic injection moulding with the excellent mechanical and thermal characteristics of metallic materials. Based on many years of experience in the production of precision components using machining technology, OBE has advanced to become a specialist in the field of Metal Injection Molding technology since 1996 and produces high-precision metal components for a wide variety of industries under the brand name mimplus®.
It consists of four processing steps:
|A metal powder of the desired composition is mixed with a thermoplastic binder and a small quantity of a lubricant (e.g. paraffin) and granulated to become a feedstock. The compound increases the injection capacity of the metal powder and guarantees the shape retention of the blanks.|
|The feedstock is formed and demoulded in a mould using conventional injection moulding machines. Blanks produced like this are called "green parts". They are up to 20% larger than the finished product as a result of the volume quantity of binder (Fig. 3), but still however exhibit all the typical geometrical characteristics of the finished component. The sprues can be removed and directly regranulated for the next injection moulding process.|
|Debinding can be carried out catalytically, thermally or via water depending on the type of feedstock. The binder is hereby removed from the component until a residual binder content of 2-3 % remains. This backbone guarantees the stability of the "brown part" for the subsequent process.|
|In the last processing step the components are sintered at temperatures of between 1200°C und 1400°C depending on the material. The remaining binder is completely removed in special sintering ovens in an inert gas atmosphere or in vacuum. The shrinkage of the component as a result of the sintering is already calculated as a dimensional feature of the mould.|
Components produced using the Metal Injection Molding process are free of residue and attain density values of almost 100 %. They have similar characteristics to e.g. machined components; the MIM process is environmentally-friendly and does not waste resources as the granulates are recycled.