Material Drying
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Bubbles or voids appear inside the product
Problem Phenomenon
Bubbles or voids appear inside the product, especially obvious in transparent products, bubbles are round or irregularly shaped distributed in the thick wall center
Cause Analysis
High moisture content in raw material, vaporizing during injection
Insufficient holding pressure, thick wall center not compacted
Injection speed too fast, air entrained
Cooling time insufficient, product demolded before the interior solidified
Poor mold venting, cavity air entrained
Solution
Fully dry the raw material, moisture content ≤0.02%
Increase holding pressure and holding pressure time
Adjust injection speed to avoid being too fast
Extend cooling time to ensure complete solidification
Improve mold venting
Key Takeaway
Bubbles/voids need to be addressed from drying, holding pressure, and venting
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