Material Drying
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Bubbles in thick-walled EAA '2079851475616104452
Problem Phenomenon
Dense bubbles of 0.1-0.5mm appear inside thick-walled EAA injection molded products, concentrated at the center of the wall thickness
Cause Analysis
Insufficient holding pressure <40MPa or short holding time, the thick wall center is not compacted; raw material contains moisture; injection speed too fast entrains air; poor mold venting
Solution
1) Increase the holding pressure to 60-80MPa; 2) Extend the holding time so that the thick wall is fully compacted; 3) Fully dry the raw material to moisture content <0.02%; 4) Add vent grooves or vent pins to the mold; 5) Use gradual deceleration injection to avoid air entrainment
Key Takeaway
Thick-wall bubbles are caused by a combination of insufficient holding pressure, moisture and poor venting
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