Gammaflux: Hot runner temperature control systems with integrated sequential valve gate controllers and overfeed monitoring function

Gammaflux Europe GmbH (www.gammaflux.de) has now integrated into its high-performance hot runner temperature control systems a sequential valve gate controller (SVGC). Designed for use with hot runner systems with needle valve nozzles, the SVGC opens and closes each nozzle individually and independently of all the others. This permits sequential filling of the cavity, above all in cases where large parts are being moulded, thus preventing the formation of flow lines or at least shifting the flow lines to those areas of the moulding that are not mechanically and/or optically critical. Moreover, the reduced flow length permits a reduction in wall or section thickness and hence a reduction in part weight. Since the holding pressure is uniform throughout the entire moulded part, the reproducibility of the parts is vastly improved. The integration of the sequential valve gate controller into the hot runner temperature control system also offers the processor the following benefits:

• There is no need for a separate controller unit, thus saving space. The SVGC and the entire hot runner temperature control system are clearly displayed on the same touch screen.

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• The largely self-explanatory operator prompt permits not only easy setting of all hot runner and SVGC parameters but also fast and efficient troubleshooting.

• The current operating status of each individual needle valve nozzle is clearly indicated on the screen by a bar display (green = open; red = closed).

•The response speed of the solenoid valves that trigger the needle valves is 1 ms. This ensures the necessary reproducibility for a consistently high quality of part.

The integrated sequential valve gate controller is available for use with 8, 16 or 32 pneumatically or hydraulically actuated needle valve nozzles.

Heat output monitoring facility avoids scrap and mould damage

All Gammaflux hot runner temperature controllers are equipped as standard with a heat output monitoring device for each individual control zone. If the heat output requirement for a particular zone increases to a pre-set limiting value – e.g. 20% higher than the mean value for the zone in question – the controller gives a visual and/or acoustic alarm. The main cause of an inadmissable increase in heat output is:

• either the overfeeding of the mould cavity – the surplus melt that is then forced out of the cavity at the parting line causes an increased dissipation of heat to the cold mould

• or a leak in the mould cooling system – the leaking cooling water may drip onto the hot runner manifold or the hot runner nozzles and cool them down.

Such malfunctions result in scrap and may in the medium term cause permanent damage to the mould. The heat output monitoring facility gives warning in good time and, in addition, enables the processor to pinpoint the malfunction exactly, this being a particularly important advantage in applications involving large multi-cavity moulds.

Gammaflux Europe GmbH, Wiesbaden, Germany

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