Other recent innovative applications for metal injection moulding

A small metal injection moulded component for the giant A380 Airbus is the valve holder (Fig. 20). The parts were previously made from pressed metal, small machined pillars, washers, nuts, etc, using 22 items which have been replaced by just 2 MIM parts.

The MIM-316L stainless steel components hold a de-icing valve and the one-piece metal injection moulded parts have recesses in the tops of the pillars, which are used for riveting a plastic micro-switch into place. Massive cost savings were achieved, not just for the cost of the parts, but also in as-sembly time and the cost of ordering and stocking the individual parts.

The nut (Fig. 21) belongs to a new tightener system for special self-drilling flat head screws for facade construction. Two parts are assembled in a sleeve and form the clamp which encloses the complex de-sign of the flat head screw.

The inner shape of the nuts is the negative contour of the screw head. It provides optimal grip and requires a highly wear resistant material. Only metal injection moulding is able to cost-effectively re-produce this part for the specified service life of 2000 - 5000 tightening operations.

The nuts weighing 5.8 g each are made from MIM-Fe7Ni. In order to achieve the required service life it is important that the density is above 7.8 g/cm³. The parts are case hardened and subsequently anti-friction coated.

In comparison to the manufacture by machining, metal injection moulding results in cost savings of 85%. About 20,000 pieces are produced per year. The nut received the EPMA Innovation in PM Award 2004.

The mounting unit (Fig. 22) is part of a laser measuring instrument. It holds in its centre a precisely positioned glass prism. The assembly of mounting unit and glass prism is positioned within a lens system. The purpose of the glass prism is to deflect a laser beam. The distance measuring instrument of which the mounting unit is a critical part is used for surveying tasks such as staking out, point survey for land registers and mapping, and simple determination of distances and angles. It can be used for distances up to 5000 m with an accuracy of 2ppm. Since the instrument must work accurately at temperatures from –20°C to +50°C, the coefficient of thermal expansion had to match with that of the glass prism.

A MIM-Fe7Ni alloy sintered to a density of 7.8 g/cm³ has been chosen for this application. Injection moulding is particularly difficult since all cross-sections are between 0.5 and 0.7 mm thin and the material must fill over long distances. The diameter of this award-winning metal injection moulded part is 43 mm and the weight is only 5 g.

After sintering a critical dimension is wire EDM machined and the part is black chromed for optical reasons. This part is a masterpiece demon-strating the capabilities of metal injection moulding and gives cost savings over a machined part (the only alternative production method) of more than 95%.

Connector for hydraulic circuits

The connector part for hydraulic circuits shown in Fig. 23 has been converted to a single metal injection moulded part from an original design which was welded from 3 machined parts. It features 2 external threads (M10x1.5 and M10x0.75) and internal holes with tolerances of 0.03 mm. The minimum wall thickness is 0.15 mm on the adaptor tip. The part is made from 316L stainless steel and weighs 23 g. It is used in the as-sintered condition without subsequent heat treatment.

Housing for a fire resistant door lock

This housing for fire resistant door locks (Fig. 24) features internal holes and threads (2xM2 and 2xM3), knurlings, and in some faces the wall thickness is as thin as 1 mm. It substitutes and investment casting which included several machining steps in the manufacturing process. The part weight is 112 g, the mate-rial 310N heat resistant stainless steel. Metallurgical status: normalised.

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