Common problems during the bottle stretch blowing process. Part 5

Problem No. 9 :  Bottle neck material accumulation, with waves.

Symptom: Around 5-8 mm blow the bottle neck ring, the wave-like stripes exist. And the neck rings may be not so round, but in a elliptical shape.

Causes:

l When the preforms on the way to the mold cavity, been transported to the mold cavity by the mechanical jaws. The preforms contacted the cold mold, and been cool down before stretching and blowing.

l The pre-blow time is too early before stretching, then the stripes will appear during the stretching process.

Solutions:

l Reduce the pre blow pressure.

l Make the pre blow time to be a little delayed.

l Increase the temperature for the neck heating lights inside the heating oven.

l Other heating lights temperature are too high. Try reduce a little for all heating light.

Problem No.10 : Not vertical core of the bottles

Symptom: The bottle design & structure is not in straight with the core of the bottles. Sometimes, it may cause milky color at the bottom of the bottles. The bottom of this kind of bottles are not strong, and they may get cracks and explode.

Causes:

l Check the stretch rod. At the bottom of the bottle mold, there is a small spot, which supposed to be at the correct target position of the stretch rod end. That small spot must be very straight with the stretch rod.

l If the stretch rod is in correct position, in line and be very straight with the small spot at the mold bottom, then it means the center is being changed during the blowing process.

Solutions:

l The preform is not at the center of the mold. Try fix it.

l The blowing nozzle is not at the center of the mold. Try fix it.

l The mold neck is too tight with the preforms. Try fix it.

l The stretch rod is not straight.  Try fix it.

l Check to see if the stretch rod is in right length.if the stretch rod is not right, then it will drop to the end very slow, or even can not get to the bottom at all. Try fix it.