Externally heated hot runner
From Plastics Wiki, free encyclopedia
Externally heated hot runner channels have the lowest pressure drop of any runner system (because there is no heater obstructing flow and all the plastic is molten), and they are better for color changes none of the plastic in the runner system freezes.
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Advantages
- Improved distribution of heat.
- Better temperature control.
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Disadvantages
- Higher cost and complicated design.
- Should take into account thermal expansion of various mold components.
