Problems often encountered in the blow molding process

1. Thin on the top and thin on the bottom: postpone the pre-blowing time, or reduce the pre-blowing pressure to reduce the air flow.
2. Thicker on the bottom and thinner on the top: the opposite of the above.
3. There are wrinkles under the bottleneck: the pre-blowing is too late or the pre-blowing pressure is very low, or the billet here is cold but not good.
4. White bottom: the preform is very cold; too stretched; the pre-blowing is too early or the pre-blowing pressure is very high.
5. There is a magnifying glass at the bottom of the bottle: there is a lot of material at the bottom of the bottle; the pre-blowing is too late and the pre-blowing pressure is very low.
6. There are wrinkles in the bottom of the bottle: the temperature at the bottom is very high (cold at the gate is not good); the pre-blowing pressure is very low and the flow is very small.
7. The whole bottle is turbid (never transparent): cold is not enough.

8. Partial whitishness: Excessive stretching, the temperature here is so low, or the pre-blowing is too early, or the stretch rod is encountered.
The following are the three most common undesirable phenomena in blow molding machines:
(1) The whole wall of the bottle of the bottle blowing machine is very thin. The main reason is that the preform stretching temperature is very high and the preform stretching ratio is very large.
(2) The bottom of the bottle of the bottle blowing machine is thin and the upper part is thick. The reason is that the stretching speed is very slow, the first blow molding pressure is very high, and the second blow molding time is absolutely inappropriate. During stretch blow molding, the temperature of the upper part of the preform is low and the temperature of the upper part is high.
(3) The bottom of the bottle of the bottle blowing machine is thick and the upper part is thin. This is caused by the very fast stretching speed, the very low primary blow molding pressure, the improper control of the second blow molding time, and the improper temperature control of each part on both sides of the stretch blow molding.