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FILLCONTROL: Automatic Valve Gate Control for Cold Runners
9/17/2013 |
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In hotrunner technology control systems are successfully used since many years for the automatic balancing of multi cavity molds. This is because the simultaneous filling of all cavities is a precondition for the optimum part quality. These conditions are achieved by automatically detecting the melt front in the single cavities and by controlling the temperature of the hotrunner nozzles in case of deviations.
For cold runner molds - for instance in case of liquid silicone rubber applications - it is even more important to achieve an equal filling because otherwise the different volumes in the cavities will also cause a different compression after cross-linking. The results are unfilled respectively inhomogeneous parts which sporadically occur in one or the other cavity.
The solution for this problem is again the automatic detection of the melt front via cavity pressure or cavity temperature sensors and the automatic delay of the valve gate opening until an equal filling will be achieved. There is a choice of either balancing the average fill time or to control the desired target fill time.
This control method can be used for thermoplastics as well as for liquid silicone rubbers or elastomers. Likewise it can be used to balance and control conventional multi cavity molds as well as family molds.
FILLCONTROL is a modular system to monitor and control the injection molding process. For the automatic valve gate control the new Control V module comes into operation. |
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