Material Drying
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GPPS Transparent Part Bubbles
Problem Phenomenon
Bubbles appear inside transparent products, and the optical appearance is unqualified.
Cause Analysis
Moisture vaporizes after the pellets absorb moisture; barrel temperature too high causes slight PS degradation to produce gas; insufficient feeding in thick-wall areas forms vacuum bubbles that also appear as bubbles.; during on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based only on experience
Solution
①Dry pellets at 70~80°C for 2 hours; ②control melt temperature not too high; ③strengthen holding pressure feeding; ④improve mold venting.; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
GPPS bubbles are identified by three sources: moisture, degradation and vacuum bubbles; location and accompanying features can distinguish the types.; after confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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