Molds & Tooling
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PET oligomer precipitation contamination
Fenómeno del problema
Waxy deposits appear on the mold surface and the bottle surface, requiring frequent shutdowns to wipe the mold, and preform transparency is also affected.
Análisis de la causa
Oligomers in PET migrate to the surface and precipitate at processing temperature, adhering to the mold; high oligomer content in the raw material or an excessively long thermal history aggravates the precipitation phenomenon.
Solución
①Switch to a resin grade with low oligomer content; ②regularly wipe the mold with a special cleaning agent; ③control the processing thermal history; ④evaluate raw material batch differences.; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Conclusión clave
Oligomer precipitation is a defect mainly of raw material factors; material selection and control of thermal history are the fundamental cure, while mold wiping can only treat the symptoms.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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