1. There are burn marks on the surface of the tube. The possible cause is that the temperature of the body or the nose is too high; the nose and filter are not cleaned; there are impurities in the pellets; the thermal stability of the raw materials is poor or the thermal stability dose is too small; the temperature control instrument fails.
2. There are black stripes on the surface of the pipe. The possible cause is that the temperature of the machine head is too high and the filter is not cleaned.
3. The surface of the pipe is dull. The temperature of the die may be too low or too high.
4. There are wrinkles on the pipe surface. It may be caused by uneven temperature around the die; the cooling water is too hot; the traction is too slow.
5. The inner wall of the pipe is rough. It may be that the temperature of the core rod is too low; the temperature of the body is too low; the temperature of the screw is too high.
6. There are cracks on the inner wall of the pipe. The material may be impurity; the temperature of the core rod is too low; the temperature of the body is low; the traction speed is too fast.
7. There are unevenness on the inner wall of the tube. The temperature of the screw may be too high; the screw speed is too fast.
8. There are bubbles on the inner wall of the tube. It may be expected to be damp.
9. Uneven tube wall thickness. The die and core die may not be aligned; the temperature of the head is uneven; the traction is unstable; the compressed air is unstable.
10. The pipe is bent. The wall thickness of the pipe may be uneven; the temperature around the machine head is uneven; the cooling groove of the machine head is not aligned with the traction cutting center; the holes at both ends of the cooling groove are not concentric.
11. The product is brittle. The degree of plasticization of the machine may not be enough; the screw speed is too fast; the temperature of the machine head is too low; the resin viscosity is too high.
12. Longitudinal or transverse shrinkage of the pipe may be large (transverse); the traction speed is relatively high (longitudinal).
13. Suddenly the material is discharged slowly. The temperature of the screw feeding section may be high; the machine body enters water; the melt pressure of the machine head is small.