i-Mold: Sprue adjuster makes runner systems flexible

With an in the truest sense of the word direction-giving innovation, the firm of i-mold GmbH & Co. KG (www.i-mold.de) has now made the operation of multicavity and family moulds considerably easier: the world´s first of its kind, this new development – a sprue adjuster – enables to change the direction of melt flow in the runner system of the injection mould. By a simple turn of the sprue adjuster, the flow of melt to the individual mould cavities can be selectively freed or blocked. The setting of the sprue adjusters is done manually from the mould parting surface when the mould is open. This is very easy to do and necessitates only a brief interruption of the moulding cycle. Thus it is possible, for example, to isolate a defective cavity without risking the damage that can easily occur whenever makeshift measures are taken to block the flow of melt. The sprue adjusters can be used in a similar way in family moulds, e.g. to isolate a cavity that is needed for some applications but not for all. Stefan Bernhard, Aha Kunststofftechnik, Fränkisch-Crumbach/Germany, explains: "Precisely in the case of multicavity injection moulds it is frequently the case that a defective cavity has to be put out of service until the next routine mould maintenance can be carried out. In this way we can avoid the time-consuming and costly work of sorting out the rejects. The sprue adjuster is extremely useful in such cases. A copper pin used to be hammered into the gate to block a defective cavity, but that often proved to have been a very costly measure when it finally came to repairing the mould."

The main component of the sprue adjuster is the rotating cylindrical body which is tightly fitted and screwed into the mould and can be set to any desired position by means of an Allen screw. The toolmaker machines the melt flow-ways into the cylindrical body in such a way that it is possible, by turning the cylindrical body, to open or close them as required. The cross-section of the melt flow-ways (circular or trapezoidal) and their arrangement (on one side or on both sides) can be adapted to the specific mould configuration by the toolmaker. The rotating cylindrical body is sealed by a high-temperature Viton O-ring. The sprue adjusters are available in a choice of two versions, either with or without a borehole for the lead-through of an ejector pin.

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The sprue adjusters permits the processing of basically all thermoplastic polymers, including filled, reinforced and flame retardant polymers, and all thermoplastic elastomers. The sprue adjusters are the product of a joint project: the idea and the applicational advice and support come from i-mold, while the manufacture of the sprue adjusters is handled by Cumsa, Barcelona/Spain, a specialist in the manufacture of standard mould units.

i-mold will be presenting the new sprue adjusters on its stand at Euromold (Frankfurt am Main from 3rd to 6th December 2008, Stand D28, Hall 9.0). Visitors will be able to see for themselves how easy these innovative mould components are to install, use and handle.

Bild: This innovative sprue adjuster is available in three sizes (bottom). The toolmaker machines the melt flow-ways into the cylindrical body. Simply by rotating the sprue adjuster it is possible to change the direction of flow of the melt (top). The feed of melt to a defective cavity, for example, can be cut off temporarily until the cavity can be repaired.

EuroMold 2008, 3.-6. December 2008, Frankfurt am Main, Stand D28, Hall 9.0

i-Mold GmbH & Co.KG, Brensbach, Germany

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