Extrusion & Post
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LDPE Blown Film Frost Line Management
Problem Phenomenon
When the bubble frost line is too low, the film is hazy; when the frost line is too high, the bubble is unstable and film breakage is frequent.
Cause Analysis
The frost line is the visualized position of bubble cooling and crystallization: too low a frost line means excessive cooling and film haze; too high a frost line means insufficient cooling and the bubble sways unstably; the balance of air ring air speed and volume determines the frost line.
Solution
①When the bubble is unstable, first reduce air ring air speed to raise the frost line; ②When the film is hazy, increase air speed to press down the frost line; ③Coordinate with internal cooling IBC adjustment; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Key Takeaway
The frost line is the steering wheel of the blown film process; the balance between bubble stability and film transparency is all adjusted by it; After confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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