4 main PCO28MM PET prefrom mold injection problems
- PET preform bottom whiting: main reason is insufficient hot runner temperature or material temperature is not high enough, it can use something to have a better insulation, get the nozzle temperature increased, an appropriate increasing material temperature and speed up injection speed while reducing the packing pressure, and slow down the speed of cooling water.
- Opaque PET preform :main reason may be insufficient drying, insufficient plasticizing, too thick PET preform wall, poor cooling,foreign material mixed in the barrel.solution:dry the PET material over 4 hrs in heating oven,increase the material temperature and rotation speed of screw,check if the drying temperature is too low,or wrong injection volume,and the drying temperature over 160 degree and moisture below 0.02%.the color change from clean to opaque:main reasontoo high ejection temperature,solution:strength cooling,prolong cooling time and change the injection time.
- Haze on one side of PET preform: main reason may be because the too high holding pressure and bias gate hole on the bottom of the cavity of PCO28MM PET prefrom mold. Solution: reduce the injection and holding pressure, correct the mold gate position.
- Yellowing or sliver streak on PET preform:main reason is probably the PET material get decomposition because the temperature is too high, solution: lower the drying temperature, prolong drying time.adjust the injection speed, lower material temperature and reduce heat nozzle temperature.
