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Common Problems and Solutions of PET Bottle Blow Molding Process

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2021-12-07

PET plastic bottle blow molding process is a two-way stretching process, blow molding process is a two-way stretching process, blow molding process has: stretch-pre-blow-main blow, three action time is very short, but must cooperate well, especially the first two steps determine the overall distribution of material, blow bottle quality is good or bad. Therefore, it is necessary to adjust the starting time, stretching speed, starting and ending time of pre-blowing, pre-blowing pressure, pre-blowing flow rate, etc. If possible, it is best to control the overall temperature distribution of the preform and the temperature gradient of the inner and outer walls of the preform.

Common problems and solutions in the process of blow molding are as follows:

1. Upper thickness and lower thickness: delay the pre-blowing time, or reduce the pre-blowing pressure to reduce the air flow.

2. Lower thickness and upper thickness: opposite to the above.

3. There are wrinkles under the bottleneck: the pre-blowing is too late or the pre-blowing pressure is too low, or the billet cooling here is not good.

4. The bottom is white: the preform is too cold; excessive stretching; pre-blowing too early or pre-blowing pressure too high.

5. There is a magnifying glass at the bottom of the bottle: there is too much bottom material in the bottle; The pre-blowing is too late and the pre-blowing pressure is too low.

6. There are wrinkles in the bottom of the bottle: the temperature at the bottom is too high (the cooling at the gate is not good); The pre-blowing pressure is too low and the flow rate is too small.

7. The whole bottle is cloudy (opaque): cooling is not enough.

8. Local whitening: excessive stretching, the temperature here is too low, or the pre-blowing is too early, or the stretching rod is touched.

9.PET plastic bottle bottom eccentricity: may be related to preform temperature, stretching, pre-blowing, high pressure blowing, etc. Reduce the temperature of the preform; accelerate the stretching speed; check the gap between the pull rod head and the bottom mold; delay the pre-blowing to reduce the pre-blowing pressure; delay the high-pressure blowing; check whether the preform is eccentric.

The most common production technology of PET plastic bottles is blowing bottles, as well as extrusion blowing, injection molding and other technical processes. It is impossible to have no problems in the production process, but the problem itself is the problem of the material and the machine, so it depends on our careful inspection in the production.

PET injection molding process common problems and solutions

PET Bottle Blowing Common Problems

PET injection molding process common problems and solutions

PET Bottle Blowing Common Problems