Injection Molding
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Nozzle blockage in general-purpose polyethylene '2079851475616104452
Problem Phenomenon
During injection, the melt cannot be normally injected from the nozzle or the injection amount decreases, and the injection pressure rises abnormally.
Nozzle blockage leads to short shots or complete inability to produce, usually caused by cold material or impurities blocking the nozzle hole.
Cause Analysis
（1）The nozzle temperature is low, and the melt cools and solidifies at the nozzle
（2）The cold slug well of the mold sprue is improperly designed, and cold material flows back into the nozzle
（3）The raw material contains impurities that block the nozzle hole
（4）The nozzle hole diameter is too small or the internal structure of the nozzle is unreasonable
（5）The nozzle is poorly aligned with the mold sprue, and eccentricity produces flash and material jamming
Solution
（1）Raise the nozzle temperature to a reasonable value within the range of 160-260°C, 5-10°C lower than the front barrel temperature
（2）Check the cold slug well of the mold sprue to ensure that the cold slug well size is sufficient
（3）Check the cleanliness of the raw material, and install a magnetic frame and filter screen on the hopper
（4）Select a nozzle with a suitable hole diameter, generally the nozzle hole diameter is 0.5-1mm smaller than the small end of the sprue
（5）Correct the alignment of the nozzle and the mold to ensure that the coaxiality is within 0.05mm
Key Takeaway
Nozzle blockage is caused by cold material solidification or impurities, and needs to be solved from nozzle temperature, cold slug well design, and raw material cleanliness.
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