Metal injection moulding process

Metal injection moulding (MIM) frees designers from the constraints of shaping metals like stainless steel, nickel iron, copper, and titanium. This integration offers greater design freedom and enhances part performance.

Very fine metal powders are mixed with thermoplastic and wax binders to create a homogeneous, pelletised material that can be injection moulded like plastic. This method achieves 95-100% of theoretical density, allowing for ultra-high density and close tolerances in high-production runs, unlike standard powder metallurgy.

The feedstock is heated and injected into a mould cavity under high pressure, enabling the production of highly complex shapes with shorter cycle times. The resulting component, known as a “green” part, mirrors the final design but is approximately 20% larger to account for shrinkage during the subsequent sintering phase.

The debinding process involves a controlled method to remove most of the binders from the “green” part, preparing it for sintering. After debinding, the component is known as a “brown” part, ready for the final step in its production.

During the sintering process, the fragile “brown” part, held together by a small amount of binder, is subjected to temperatures near the melting point of the material. This step eliminates the remaining binder and finalises the part’s geometry and strength, resulting in a fully dense and robust component.