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Causes and solutions of common problems in blowing molds

Update:03-09-2020
Summary:

Phenomenon 1: Bottle mouth swells, blowing bottle out o […]

Phenomenon 1: Bottle mouth swells, blowing bottle out of gas

Reason: As the surrounding space temperature gradually increases, the cooling effect of the airflow passing through the oven is reduced. As a result, the temperature of the mandrel rises, which is transmitted to the threaded area.

Solution: External cooling can be used to control the temperature of the threaded area and mandrel when the preform passes through the oven; adjust the position of the cooling plate so that it can provide stronger protection to the threaded area of ​​the preform. In addition, a well-designed cooling plate may be a better countermeasure.China Plastic pail mould Suppliers

Phenomenon 2: The bottom is damaged

Reason: The temperature at the bottom of the preform is low, and when the stretch rod moves toward the bottom of the mold against it, microcracks are formed.

Solution: The best way is to make the end of the preform neither too cold nor too hot between stretching and breaking. In addition, the gap between the stretch rod and the bottom of the mold is also critical, and only the largest necessary gap can be used to ensure the positioning of the door.

 

 

Phenomenon 3: Transition

Reason: The problematic cavity may be caused by insufficient air blowing. If the preform temperature during blowing is lower, the film bubble blows more slowly, and the problem becomes more obvious. The lighter bottom also means that the material has reached its natural stretch limit before the entire container is formed.

Solution: Ensure that all the ventilation holes on the mold are not blocked; ensure that the blowing can be completed in the shortest time, otherwise, additional cooling will be brought to the PET material when blowing; check the working status of the valve to ensure blowing Time positioning is accurate.

Phenomenon 4: The neck is bent

Reason: The problem is generally caused by mechanical operation, and the thick material on the neck causes deformation after closing the mold.

Solution: if the material on the bottle neck is too thick, the bottleneck will become crooked when the mold is clamped; in addition, the alignment of the conveying arm and the blowing center is also a cause of this problem.

Phenomenon 5: The screw of the bottle mouth is damaged

Reason: the preform is sent into the mold cavity by the conveying arm, and the thread must be stressed during clamping. When the position of the conveying arm is inaccurate, when it lifts the preform ring from the mold, if the weather is cold, blow the core pressure It will press on the closed surface of the preform and will not cause damage. Unfortunately, when the weather is hot, the exhaust of the thread will be subjected to tensile force, because the preform is forced to be aligned by the blown core that has been washed down.