The defect of extrudate in the extrusion process in the form of melt fracture could only be evidenced in the semisolid state of PP melt.
在挤出过程中，以熔体破裂形式出现的挤出物的缺陷只有在PP熔体处于半固体状态时才能观察到。
2
Uneven deformation and extrusion drape in the different pass when rolling cause long strip defect on the surface. Defects on the surface and near surface are the main cause for cold heading to craze.
The inner spiral copper tube produced by extrusion-rolling process has a kind of special line defect, which influences the production yield remarkably.