Common quality defects and solutions in bottle blowing packaging materials

Inner neck creases (commonly known as 'rings')

Symptoms: Inner folds are often found at 5-8 mm below the convex ring, showing an obvious ring shape, and there are obvious creases on the outside when touched by hand.

 

Factors: Both are related to the easy stretching of the preform from the thinner end of the cone segment. In severe cases, the stretching will start from the parallel segment below the convex ring. When the preform is stretched, it will gradually expand as the stretching rod goes down It gets cold, and the material at the second place is very thin, so it gets cold quickly. Natural wrinkles are produced during the blowing process.

 

Solution:

1. Readjust the position of the hot spot so that it is close to the main body of the preform;

2. Adjust the pre-blowing air intake time, make sure it is not too late, and check whether the pre-blowing solenoid valve is normal;

3. Caused by a nozzle failure, it is necessary to check whether the cylinder seals, diffusers, springs, solenoid valves and fixing sleeves are running smoothly up and down (these will cause the nozzle to run slowly);

4. The material in the area is very thin, increase the thickness of the material in the area (reduce the temperature in the area or increase the temperature in the area where the bottle is thicker).

 

Bottleneck accumulation (commonly known as 'flower neck')

Symptoms: Bottleneck accumulation is often found in wavy stripes 5-8mm below the convex ring, and the convex ring is irregular or oval.

Factors: when the preform is sent from the transfer arm to the mold cavity, it is cooled first when it encounters the cooled cavity or the pre-blown air is too early during stretching, and the preform is pulled down with the stretch rod during stretching extended to form.

Solution:

1. Too much pre-blowing pressure;

2. The pre-blowing time is too early;

3. The temperature in the first zone is not enough (increase the heating percentage of the first zone or increase the number of its lamp tubes);

4. The light stand is too high, adjust the position of the light stand;

5. The temperature in the second zone is too high or the temperature in other zones is too high (this is to adjust the temperature of each zone according to the actual partition weight and thickness of the bottle to reduce the bottleneck material).

 

Off center

Symptoms: The structure of the bottom of the bottle is not concentric with the container, and in severe cases, the bottom corner will be whitened. The bottom of this bottle has poor stress and is prone to cracks or bursts.

Factors: This question is related to two points, and to recognize which point needs to observe the position of the stretching point of the stretch rod. If the position of the stretch point is off-center from the pour point on the bottom of the preform, the stretch rod is not aligned with the mold. If the position of the stretch point is concentric with the pouring point of the preform, it means that the stretch rod, although positioned correctly, has shifted during the blowing process.

 

Solution:

A. Mechanical reasons

1. The preform and the mold are not aligned;

2. Mismatch between mouthpiece and mold;

3. The preform and the upper part of the mold are too tight;

4. The stretch rod is bow-shaped;

5. The sliding guide rail or linear bearing of the stretch rod is abnormal;

6. The adjustment of the buffer pad of the stretching rod is not suitable, resulting in a slow down of the stretching or the inability to completely drop to the end.

 

B. Electrical failure

1. Too much pre-blowing pressure;

2. The pre-blowing time is too early;

3. The stretch rod solenoid valve is dirty, the control valve seal is worn or the coil reel is broken;

4. Stretching cylinder exhaust blockage (muffler blockage);

5. The control pressure of the stretching cylinder is low (gas circuit turning loss);

 

Pearlescent - whitish bottom corner

Symptoms: Pearlescence can occur anywhere on the bottle, but is most common at the corners of the bottom of the bottle. A small amount of bluishness in the corners of the bottom of the bottle is normal and indicates that the blowing process has achieved maximum biaxial stretching.

Factor: Pearlescence is a direct result of stretching beyond the natural stretching limit. In fact, the microstructure of the material is stretched and torn. The material in this area is significantly thinner.

Solution: Because the material in this area is relatively thin, it is better to increase the material in this area. If the material in this area is sufficient, consider the reason again:

1. Make sure not to be eccentric;

2. Extend the pre-blowing time and pre-blowing intake time, and reduce the pre-blowing pressure;

3. Ensure that the extension gap is correct (2/3 of the bottom thickness of the blown preform, if the gap is too large, it will cause whitening;

4. Ensure that the extension runs flexibly and smoothly (if the extension runs slowly up and down, it will produce whitening);

5. The temperature of the preform is low or the overall temperature of the preform is low during heating.