Molding Process
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PBT Voids and Sink Marks
Problem Phenomenon
Voids appear inside thick-walled products with sink marks on the surface, and holding pressure adjustment has inconsistent effects
Cause Analysis
PBT has a large shrinkage rate and thick-wall areas have high feeding demand; insufficient holding pressure and time form voids and sink marks; but PBT solidifies fast, the holding window is short and needs precise setting
Solution
①Optimize holding pressure and time according to wall thickness; ②Position the gate close to the thick-wall area; ③Thin down thick-wall structures; after adjustment, take samples continuously to verify the effect, and resume mass production only after confirming stability
Key Takeaway
The difficulty of PBT voids and sink marks lies in fast solidification and a short window; precise holding and structural thinning are used together; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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