Extrusion & Post
12 görüntüleme
Excessive Shrinkage Rate of Block Copolymer Polypropylene Extruded Products
Sorun Belirtisi
The extruded product shrinks significantly in size after cooling, exceeding the tolerance range.
Excessive shrinkage rate makes the product size smaller, affecting fitting and use.
Neden Analizi
（1）The crystallinity of block copolymer polypropylene is high, and cooling crystallization causes volume shrinkage
（2）The melt temperature is high, the volume expansion is large, and the shrinkage after cooling is large
（3）The cooling rate is slow, the crystallinity is high, and the shrinkage is large
（4）The haul-off speed is too slow, and the product expands at the die
（5）The raw material grade is improperly selected, and the shrinkage rate is large
Çözüm
（1）Appropriately reduce the barrel temperature to a lower value within the 200-270°C range
（2）Appropriately accelerate the cooling rate, reduce the crystallinity, and reduce shrinkage
（3）Adjust the haul-off speed and appropriately increase the draw ratio
（4）Select a grade with a small shrinkage rate, shrinkage rate 1.2-2.0
（5）Reserve shrinkage allowance in mold design
Temel Çıkarım
Excessive shrinkage rate is caused by high crystallinity or high temperature, and needs to be solved by controlling temperature and cooling rate.
Bu faydalı oldu mu?
0 kişi bunu faydalı buldu
Geri bildiriminiz için teşekkürler!