The last years have shown a notable increase of applications for cold runner systems in the areas of elastomer or LSR (Liquid Silicon Rubber).
SIGMASOFT allows you to examine the cold runner systems in their whole complexity. Especially for LSR it is necessary to reach a certain temperature distribution in the cold runner. There, the use of different mould materials is in fact the prerequisite for a secure filling process.
Exact temperature gradients are calculated in a simulation that couples heat flow and polymer flow.
The evaluation of multiple production cycles gives the user the ability to calculate the quasi-stationary state of the mould. (Also see multi cycle simulation). This inhomogeneous temperature distribution is now used for the calculation of the subsequent filling and heating phase to deliver exact results.
In the first cycle, the cold runner system and the cavities are all filled with polymer. In the subsequent cycle however, the melt is already present in the cold runner system, which reflects reality. In the new production cycle, the melt is accelerated and put under thermal strain. The animation below shows the acceleration of the melt and the mould filling. What is more, it is possible to see the heating up of nozzles and needle valves.
SIGMASOFT allows a reliable thermal rheological balancing of the whole cold runner system. There are no more surprises when carrying out mould trials.
The basis of this exact simulation is reliable material data in addition to the robustly implemented algorithms. The following figure exemplarily shows the viscosity curves of the A and B component of a LSR polymer. SIGMA comprehensively supports the user in the evaluation, interpretation, and integration of material data.
This function does not only apply for LSR materials, but also for all other tempered gating systems (cold runner and hot runner). All necessary data to display such complex processes is defined via the user-friendly graphic user interface.
"Deadwater areas" in the cold runner can be localized with the help of virtual melt particles. This is especially important for cross linking materials, because the material in such "deadwater areas" will come to a standstill, then cross links, and consequently can significantly change the required pressure demand of the injection moulding process. In the worst case, the runner clogs and must be completely cleaned. It is also possible that cross-linked material separates from those areas and flows into the cavity. It is quite obvious that the desired part properties cannot be achieved. The animation below demonstrates the "deadwater areas" in the cold runner. The advantage is that the animation shows the tracer particles in multiple cycles. That is a simple and explicit way to localize problematic areas.
If you would like to determine the correct layout for your cold or hot runner beforehand and if you would like to have less than five or more optimization loops to produce a mould, then you should contact us. Our plastics experts will be happy to help.
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