Extrusion & Post
2 Aufrufe
PET bottle shoulder stretching thin and rupture
Problembeschreibung
Thin spots and even blow-throughs appear in the transition zone between the bottle shoulder and the bottle body, and the rejects are concentrated at a specific orientation of the mold.
Ursachenanalyse
Excessively high preform temperature in the shoulder area or an excessively large design stretch ratio causes the material there to be overstretched and thinned; poor mold venting also makes the shoulder incompletely filled.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Lösung
①Lower the temperature of the heating zone corresponding to the shoulder; ②optimize the bottle shoulder design stretch ratio; ③check the mold shoulder venting; ④adjust the stretching timing.; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Wichtigste Erkenntnis
Shoulder stretching thin is the result of mismatch between temperature and stretch design; concentration at an orientation indicates local heating or mold factors, which should be investigated in a targeted manner.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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