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PET bottle production process-injection molding

Carrie Jul 23,2019 Share this post:

The molten PET is pressurized by the injection piston and flows through the hot runner, and the process of reaching the cavity is injection. The speed of injection is critical and has a significant impact on the quality of PET preforms. The injection pressure IV and the temperature of the PET are directly related to the injection speed. Generally, we recommend an injection speed of about 8-12g/s per cavity, which is beneficial to ensure a stable injection process, reduce pressure and temperature changes, ensure full and full filling of the bottle, reduce shear and stress, and is uneven. Shrinkage and deformation are reduced.


PET bottle fot oral liquid bottle


If the amount of movement of the injection piston in the entire injection cycle is 100%, the injection volume should be adjusted to about 85%-89%, and the entire cavity is already filled with the lower density hot resin. In the process of cooling, there will be a large shrinkage, which requires the amount of vacancy generated by the pressure retention.

When the injection speed is relatively slow or the PET preform is relatively large, even if it is very easy to produce a large contraction during the injection, it is necessary to appropriately increase the injection amount. On the contrary, if the injection speed is relatively fast or the preform is small, the contraction during the injection is relatively small, and the injection amount can be appropriately reduced.

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