Metal injection moulding FAQ

Manufacturing is complex – small metal components can present a challenge to engineers when material density, design flexibility and wall thickness are constrained. If you are looking for high-quality, complex, precision metal components weighing less than 160 grams, then OptiMIM's metal injection moulding process may be the best option.

Metal injection moulding, or MIM, is a process that combines two established technologies: plastic injection moulding and powder metallurgy. OptiMIM engineers can create geometrically complex, dense parts that cannot be produced using conventional powder metallurgy processes without secondary machining. With MIM, it is possible to integrate and consolidate several components into a single moulded piece, freeing designers from the traditional constraints associated with assembling several separately cast parts to achieve a net-shape component.

Our designers know that MIM is not for everyone. With so many metalworking solutions available, it can be difficult to determine when a project can benefit from the MIM process. We have compiled five frequently asked questions to help you decide whether MIM is the right process for you.

Which materials are used in metal injection moulding?

MIM materials have had their chemical compositions modified to withstand the complex metal injection moulding process. There are a wide variety of materials available for MIM, but we specialise in stainless steel, copper and low-alloy steel materials. We can also process other specialist or custom materials tailored to your mechanical property specifications.  Ask an engineer about our custom feedstock capabilities!

What part sizes are most suitable for metal injection moulding?

It is also crucial to consider the parting line and its witness mark. Every part has a parting line related to the moulding process. However, it is important to consider the application and understand how the location of the parting line might affect the part's form, fit or function. Ideally, the parting line should not be on a functional surface.

What is the porosity of metal injection moulding components?

Unlike other casting processes, MIM offers very high density with a uniform, fine grain structure. Typical MIM part density reaches 95-98%, however, some material applications with secondary hot isostatic pressing (HIP) can achieve near-wrought material density.

What minimum and maximum wall thicknesses can metal injection moulding achieve?

Wall thickness is contingent upon wall length, overall part size and part design. If the wall is localised, wall thicknesses of 0.01" or less are possible. At the other end of the spectrum, wall thicknesses of up to 0.5" are possible. It is important to note that as wall thickness increases, so do moulding process cycle time, material consumption, and debinding and sintering cycles, which inherently increase total part cost.

How do you allow for shrinkage in mould design?

Over the years, we have studied each material used in the MIM process extensively. Each alloy and geometry shrinks differently. We developed and use predictive models and factor this into our tooling design.