Extrusion & Post
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Glass Fibre extrusion melt fracture
Problem Phenomenon
Glass Fibre shows severe melt fracture when extrusion rate is too high, extrudate twisted in spiral shape
Cause Analysis
Glass Fibre melt elasticity too high, elastic recovery at die exit exceeds critical value; die L/D ratio too short <10, melt not fully relaxed; extrusion temperature too low
Solution
1) Reduce extrusion rate to 2-3m/min; 2) increase die length-to-diameter ratio to 15-20; 3) raise extrusion temperature to 160-220°C; 4) add small amount of low-elasticity resin to reduce system elasticity; 5) gradually converging die entrance design
Key Takeaway
Melt fracture is caused by elastic recovery exceeding the critical value; reducing speed and lengthening the die are the core countermeasures
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