Molds & Tooling
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PET mold temperature out of control causing crystallization
Fenómeno do problema
Under the same process, white haze on the preforms appears intermittently, and inspection finds that the mold cooling water temperature fluctuates greatly and the water channels are partially blocked.
Análise das causas
High or fluctuating mold temperature makes the preform cooling rate insufficient, providing a time window for crystallization; scaling and blockage of the cooling water channels cause uneven cooling of each area of the cavity.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solução
①Stably control the mold temperature at 5~15℃; ②clean the cooling water channels and ensure the flow rate; ③monitor the water temperature and temperature difference; ④regularly perform mold heat distribution inspection.; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Conclusão principal
Mold temperature is the key parameter for PET preform crystallization resistance; the maintenance of the cooling system and the stability of temperature control directly determine the batch consistency of preform transparency.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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