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Automatic PET Stretch Blow Molding Machine Common Failures and Solutions

blow molding process

1. Bottom molding is not full

Reason:

  1. Blowing pressure is not enough
  2. The temperature of the bottle preform is slightly low when blowing the bottle.

Solution:

  1. Check whether the high-pressure filter on the side of the mold is clear so as not to affect the high-pressure gas supply.
  2. Check the work of the road valve to ensure accurate positioning of first blowing and second blowing.
  3. Check the airflow control components of first blowing and second blowing to ensure the correct setting value and that the internal flow is smooth.
  4. Ensure that all ventilation holes on the mold are free of obstruction.

2. Neck bending

Cause:

Caused by mechanical operation, the neck accumulation is too thick to cause deformation after mold closing.

Solution:

  1. Optimize the mold structure.
  2. Clamp the convex ring too tightly at the concave part of the top plate of the mold, and fix the size of the bottle blank when it is still hot.

3. Expansion of bottle mouth, blowing and running

Causes:

  1. the surrounding temperature is too high
  2. the oven airflow cooling effect bottom.

Solution:

  1. Adjust the position of the cooling class, so that it can be stronger protection for the thread of the bottle blank.
  2. Optimize the design structure of the cooling plate.
Stretch Blow Moulding Machine of PET Bottle FST-12000 2

4. The bottom line is blue

Reason:

  1. Blowing is too high;
  2. Stretching rod pressure is not enough.

Solution:

  1. Set the blowing time and speed;
  2. Check whether the stretching rod is blocked.

5. Bottom breakage

Cause:

  1. The bottom temperature of the bottle blank is too low
  2. The position of the stretching rod is too high.

Solution:

  1. Adjust the bottom heating temperature of the bottle blank
  2. Adjust the position of the stretching rod to a reasonable setting.

6. The threaded part of the bottle mouth is damaged

Cause:

  1. The threaded area suffers from undue stretching and the surrounding high temperature makes the temperature of the threaded area of the bottle blank too high.

Solution:

  1. Make sure the conveying arm is adjusted accurately.
  2. Position the billet accurately, and at the same time reduce the heating temperature of the thread area and optimize the structure design.

7. The liquid level drops too much

Cause:

  • After filling the pet container, the solution drops and the blowing temperature is too high, forming a pearly phenomenon.

Solution:

  • Adjust the temperature of the heating furnace to avoid heating start-up or cold start-up.

8. Burst

Cause:

  1. The temperature is too high causing the bottom of the bottle is too thin
  2. The blowing time is too short.

Solution:

  1. Adjust the temperature of the bottom of the bottle.
  2. Lengthen the delayed blowing up time.
Stretch Blow Moulding Machine of PET Bottle FST-12000 3

9. Closing mold line spreading

Reason:

  • In the blowing process, the gas can not be excluded from the exhaust hole in time, constituting a thin layer of the bottle wall material blocking the exhaust hole.

Solution:

  1. Correct adjustment of the mold gap.
  2. High pressure air valve to control the airflow.
  3. Improve the design structure

10. Bottom crease

Cause:

  • External crease first blowing pressure is not enough, stretching rod too much to push the material to low; internal crease generally bar the head end of the bottle blank overheating or a delay in the beginning of the stretching pressure.

Solutions:

  1. Ensure that the blowing bottle 1 on the mold timing continuous consistent.
  2. The end of the bottle blank do not overheat.
  3. To ensure that since the beginning of stretching to blow up 1 into the previous delay is not too long.

11. Hot bottle

Cause:

  • The bottle is overheated, causing the bottle blank to crystallize again inside or outside, resulting in a burst bottle.

Solutions:

  1. Stretching time is too long.
  2. Reduce the position of the cooling plate.

12. Section gram weight uneven (neck too heavy)

Cause:

  • stretching rod stretching down and up gradually become cold, the material is very thin, cooling accelerated.

Solution:

  1. Adjust the position of the hot spot so that it solves the main body of the bottle.
  2. Adjust the position of the cooling plate.

13. Bottom eccentric

Causes:

  1. Conveying and finding the right problem
  2. The back door part is not centered with the bottle.

Solutions:

  1. Adjust the bottle blank mold conveying and finding the right.
  2. Stretching rod pressure setting is low.
  3. Blowing bottle 1 pressure is too high too early
  4. Stretching rod buffer cushion adjustment is not appropriate.

14. Pearlescent

Cause:

  • The root cause is the cold bottle. Stretching exceeds the natural stretching limit as a direct result, in fact, the bottle’s perimeter structure is stretched and torn, the formation of the tear point through the reflection into visible pearlescence.

Solution:

  1. Make sure the bottom of the bottle is located in the center.
  2. Reduce the speed of the blowing machine.
  3. Blowing 1 late into the air, stretching rod and the bottle blank contact too long.

15. Bottom gap is over poor

Cause:

  • Exceed the natural stretching limit.

Solution:

  1. To the bottom of the bottle to strengthen heat dissipation.
  2. To the overall bottle billet heating cooling, will be different temperature from the side around up.
  3. To ensure that the mold cooling water normal circulation

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