Feedstock (initial material) consists of fine metal powders, which are mixed with thermoplastics and additives in special mixing machines. The compounding process is completed when metal particles in the binder are fully homogenized. After completion of the process, the material is granulated into pellets.
In this process step, the feedstock is injected into a mould under high pressure using conventional injection moulding machines. In this way, MIM combines the advantages of the design freedom of plastic injection moulding with the excellent mechanical and thermal resilience of metallic materials.
The result of the injection moulding process is the so-called “green part”, which is up to 20% larger than the sintered final component, depending on the feedstock used.
Debinding can be catalytic, thermal or solvent-based depending on the binder system. The binder is removed from the component with the exception of a residual binder content of 2-3t% (backbone). The residual binder guarantees the stability of the so-called “brown part” for the subsequent process.
In the final step, the components are sintered at temperatures between 1200°C and 1400°C depending on the material. At this step, the remaining binder is completely removed. When sintering, the parts shrink isotopically to the desired dimensions. Sintered parts are completely metallic and have densities of >97%. As a result, they have properties similar to those of the machined components.
MIM parts, as any metal parts, can be heat-treated and further processed, for example, to achieve better tolerances at critical dimensions. MIMplus Technologies offers a wide range of post-processing technologies such as hardening, CNC machining, laser machining, surface technologies and joining techniques including the assembly of complete subassemblies.