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Günther Heisskanaltechnik Hot runner engineering for all-electric injection moulding

Editor: Eric Culp

Günther’s complete hot runner solutions promote energy efficiency and provide a technological basis for cleanroom applications.

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An important element of mould design, hot runner engineering influences the construction, efficiency and cost of heavy-duty injection moulding tools. It can also promote energy efficiency and support cleanroom moulding. Hot runner technology specialist Günther Heisskanaltechnik GmbH, working with partners Arburg and Ernst Rittinghaus, developed an efficient hot runner system that met stringent cleanroom requirements and exhibited it at the 2012 Medtec trade fair for medical technology.

The clean, efficient 16-drop Günther hot runner with electrically driven NTT valve gate nozzles ran on Arburg’s electric 520 A Allrounder injection moulding machine with a 16-cavity mould produced by Rittinghaus. The application demonstrated was the production of 1.06-g polypropylene collecting tubes—metering chambers for laboratory analysis—in 5.8-second direct-injection cycles. This all-electric system was able to deliver higher precision and use less energy than a pneumatically designed system.

For the Medtec demonstration, Günther’s design department developed a complete mould half that was then built by Rittinghaus in close consultation with Günther.

Electric valve gate

The NTT type of valve gate nozzle is installed from the parting line and can therefore remain on the machine while maintenance work is performed. Another distinguishing feature of this nozzle is that it has two fits. These not only ensure exact positioning on the pitch spacing, but also provide optimum protection for the nozzles and cabling against any leakage that might occur between the manifold and the nozzle. The manifold area is sealed off from the cable ducts by means of the fits.

The 16-cavity valve gate mould for the collecting tubes is equipped with a powerful servomotor (a linear actuator) to drive the sliding-plate mechanism. Thanks to a finely graduated gear, this drive closes and opens the valve gate needles in less than 0.2 seconds, an actuation speed that is necessary to ensure the desired short cycle times. Another advantage of the drive is that it requires little installation space.

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