The swell factor tends to decrease if the cross section of die crown is large, the die round R is small, the runner is large, the dumping temperature is high and the extrusion speed is low;
口型的冠部截面大、口型圆角R小、流胶口大，排胶温度高，挤出速度慢，则膨胀因数小；
2
This technique is also used to separate sections of rhizomes which have no pitchers: when re-potted, the section usually generates a new crown of pitchers.