burning streaks / sliver streaks / gas building streaks solution
Silvery or dark surface streaksand in exceptional cases black discolorations
- Damage to the plastic melt due to excessively high temperatures or overlong resisdence times resulting from gaseous decomposition products.
- High shear heating due to small cross sections or by sharp changes of direction in the mold.
- Reduction of the injection speed.
- Avoidance of undersized gates and sharp changes in direction (shear intensive areas) in the plastic .
- Check the controller of the hot system and the injection molding machine barrel heater
- Reduction of melt temperature, screw speed(rpm), residence time(if necessary use a smaller plasticizing unit) and back pressure.
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