Causes and solutions to common problems with PET preform molds

Preform bending after demolding

Reason: eccentric gate hole and uneven cooling can cause preform bending after demolding.

Solution: When this happens, some measures need to be taken. When the gate hole is eccentric, the mold can be corrected; in addition, reducing the holding pressure, increasing the injection speed, extending the cooling, cleaning the water channel, and increasing the cooling water pressure and water volume can solve this bending phenomenon.

The bottle body is not fully blown in the vertical direction

Reason: When this happens, it may be caused by the temperature of the unsatisfied part of the preform being too high, the unsatisfied part of the preform having cold blocks, insufficient air pressure and air volume, poor exhaust of the blowing mold, too high temperature of the blowing mold, too thin wall of the preform, and insufficient longitudinal stretch ratio of the bottle.

Solution: Adjust the temperature of the PET preform, do not touch the heated preform body and check whether the cold block has touched it, increase the gas pressure and volume, increase exhaust, add cooling water to the blowing mold, correct the mold, and increase the longitudinal stretch ratio. This problem can be solved.

Poor vertical bearing capacity of the bottle

Reason: When the wall thickness is uneven, the preform heating temperature is too high, and the bottle shape is poor, the vertical bearing capacity of the bottle will be poor.

Solution: To solve this problem, it is necessary to improve the uniformity of the bottle wall thickness, try to mold at low temperature and high pressure, and improve the bottle design.