Molds & Tooling
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PET preform hot runner crystallization blockage
Problem Phenomenon
Individual gates gradually underfill until blocked, and disassembly inspection finds accumulation of PET crystallized matter and degradation products inside the gate.
Cause Analysis
Improper hot runner temperature control makes PET crystallize and accumulate at the gate when the local temperature stays low for a long time; excessive heat-holding time during shutdown also produces degradation products that block the gate.; during on-site troubleshooting, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Increase and stabilize the gate zone temperature; ②shorten the shutdown heat-holding time; ③regularly clean the hot runner; ④optimize the startup heating process.; after adjustment, take consecutive samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Hot runner blockage is the cumulative result of long-term temperature control imbalance; standardizing shutdown and startup procedures and regular maintenance can significantly reduce the blockage frequency.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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