Processing Machinery
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Insufficient LDPE Film Longitudinal Strength
Problem Phenomenon
The film's longitudinal tensile and tear strength are low, and heavy-duty packaging bags crack during use.
Cause Analysis
A draw ratio that is too small gives insufficient longitudinal molecular orientation; excessively high melt temperature degrades molecular chains; overly fast cooling causes uneven crystallization that weakens strength.; During on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience.
Solution
①Raise the draw ratio to 1.5~3 times; ②Lower the barrel rear zone temperature; ③Adjust frost line height to optimize cooling; ④Test the molecular orientation state.; After adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability.
Key Takeaway
Longitudinal strength is built by haul-off orientation; temperature and cooling work together to ensure molecular weight and crystallization quality.; After confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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