Material Drying
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PA6 Product Bubbles
Problem Phenomenon
Internal bubbles or surface blistering of the product, mostly occurring at thick walls, affecting appearance and strength.
Cause Analysis
Moisture vaporization into bubbles is the first cause; insufficient holding pressure at thick walls forms vacuum bubbles; excessively high melt temperature decomposition also produces gas; the three mechanisms need to be distinguished (moisture is often accompanied by silver streaks, and vacuum bubbles have smooth walls).
Solution
①Strengthen drying and verify that the moisture content meets the standard with a moisture measurement method;②add holding pressure for thick-wall parts;③material temperature does not exceed the upper limit;④open or clean vent grooves at corresponding positions to ensure smooth gas discharge;⑤core-pull and reduce material at thick walls to reduce shrinkage from the source.
Key Takeaway
PA6 bubbles follow the three-way division of 'water, vacuum, decomposition': first verify drying, then look at holding pressure, and finally control temperature; moisture content of nylon material is the most common source of bubbles, and drying verification must come first.
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