The typical metal injection moulded product combines a relatively small size, high complexity of shape, high strength, medium to high surface finish, and moderate to close dimensional tolerances.

Other properties offered by materials for metal injection moulding may include a shining surface, excellent corrosion resistance, response to heat treatment, hardness and wear resistance, high electric and thermal conductivity, designed thermal expansion coefficients, special soft magnetic properties, etc.

Standards for metal injection molding

Parts consumers can rely on specifications of standard mechanical properties for frequently used metal injection moulding materials. Material standards for metal injection moulded parts have been published by the MPIF in North America covering the main metal injection moulding materials – low alloy steels, stainless steels and soft magnetic materials.

ISO TC 119 will develop a metal injection moulding standard as part of ISO 5755 Standard on Properties of Structual Powder Metallurgy Parts, and relevant mechanical properties for metal injection moulding materials are also being incorporated into the Global Powder Metallurgy Properties Database ( www.pmdatabase.com). See also the table of properties in our "Designing for powder injection molding" section.

Dimensional tolerances

The European metal injection moulding industry has issued information on the dimensional tolerances that can generally be achieved with metal injection moulded parts in the as-sintered condition (see Table).

While these tolerances are of a general, mainly informative value for the design engineer, the actual manufacturing tolerances of a specific component depend on many different factors. The tolerances defined in a part drawing should therefore always be agreed between the manufacturer and customer.

Dimensional tolerances of MIM parts

Continue to next page: Applications for metal injection moulded products, Part 1