What's Metal Injection Molding Process

Metal Injection Molding (MIM) is a manufacturing process that combines thermoplastic injection molding, metal powder metallurgy, and powder metallurgy sintering, to form complex metal shapes with high precision and repeatability. The MIM process can be used to produce small and intricate parts for a variety of industries, including medical, electronics, automotive, aerospace, and consumer products.

The Advantages of Metal Injection Molding Process

COMPLEX SHAPES

Metal injection molding can create complex shapes with tight tolerances that are difficult to achieve with other metalworking processes, such as die casting or machining. Metal Injection Molding allows to obtain complex shapes directly from the compacting tooling, without any machining operation, like teeth, splines, profiles, frontal geometries, etc. 

HIGH DIMENSIONAL PRECISION

Achievable tolerances in the perpendicular direction of compacting are typically IT 8-9 as sintered, improvable up to IT 5-7 after sizing. IT 10-13 is achieved in length depending on the component geometry; additional machining operations can improve this precision.

RELIABILITY AND REPEATABILITY IN LARGE MASS PRODUCTION

The tool stability, the technical complexity of the production devices, and the SPC control system, give high reliability and repeatability to the mass production sintered components.

SELF-LUBRICATION

The interconnected porosity of the material can be filled with oils, obtaining then a self-lubricating bearing: the oil provides constant lubrication between bearing and shaft, and the system does not need any additional external lubricant.

UNIQUE AND ISOTROPIC MATERIALS

The metal injection molding materials have homogeneous micro-structure in the three space directions, so properties are isotropic. Also, the solid-state diffusion mechanism applied to create the micro-structure allows to achieve compositions and materials which are impossible to obtain by melting, like composite materials made of phases insoluble or immiscible between them, or micro-insulated materials.

GREEN TECHNOLOGY

The manufacturing process of metal injection molding components is certified as ecological, because the material waste is very low, the product is recyclable, and the energy efficiency is good because the material is not molten. Complex shapes may require less machining and parts assembly than other metalworking processes, making metal injection molding a very cost-effective choice.

EXCELLENT SURFACE FINISH

Surface of metal injection molding components is characterised by the presence of flat areas with very low roughness, interspersed with dips corresponding to the porosity. This surface state is better than that of machined wrought materials, which feature an alternate series of peaks and troughs. The lower peaks presence allows to reduce the run-in time of the components.

VIBRATION DAMPING

The internal micro-porosity of metal injection molding parts produce a damping effect on the vibration propagation.

WEIGHT REDUCTION

Metal injection molding parts are typically 5% to 25% lighter than the same wrought components, as a consequence of the internal micro-porosity. Parts produced with metal injection molding are strong and of high quality due to the tight dimensional tolerances it produces and the uniform distribution of metal used.