A Metal Injection Mould for Couplings

Editor´s note: This issue´s featured mould is a four-cavity mould for couplings produced via metal injection moulding (MIM). Design and construction are from GKN Sinter Metals, Bad Langensalza, Germany.

The coupling (Figure 1), produced from the alloy IMET N 200 (1.5 to 2.5 percent Ni, remainder Fe) is a component in a small drive mechanism used in the automotive industry.

The injection mould (dimensions: 156 by 156 by 225 mm shut height) is constructed from standard mould components. The mould plates (2, 3) are made of the corrosion-resistant mould base steel grade 1.2085 (X33CrS16) with 16 percent chromium and have a strength of about 1,000 N/mm2.

Runner/Gating

Details of the mould are shown in Figure 2. The backup plate (4) and the clamping plate (1) are made of steel grade 1.2312 with a strength of 1,000 N/mm2. Steel grade 1.2767, hardened to 54 HRC, was employed for the two part-forming mould inserts (26, 27).

The four cavities are connected to an H-shaped runner via submarine gates (detail K) in such a way that the melt entering the cavity impinges against the cavity wall. This prevents jetting. The sprue bushing (19) serves as the connection to the injection unit of the moulding machine.

Part Release/Ejection

The ejector pins (24) are shaped to match the part and are prevented from rotating by the retaining pins (30). The moulded parts are ejected into a part handling robot, which carefully deposits them. The ejector pins (23, 25) simultaneously eject the runner system, which drops freely and, after granulating, is metered back into the moulding compound.

The shrinkage of the sintered finished parts is 17.5 percent, measured with respect to the dimensions of the part cavity/green moulded part.

Contact Information
GKN Sinter Metals GmbH
Mr. Jürgen Paal, Plant Manager Technology
Oststrasse 24
D-99947 Bad Langensalza
Germany
Tel: +49 (3603) 846227
Fax: +49 (3603) 846228