The blow molding process of the Pet Preform is a two-way stretching process. During this process, the PET chain is bidirectionally extended, oriented and placed, and then the mechanical properties of the bottle wall are increased, and the stretching, tensile and impact resistance are advanced. Strength and good air tightness. Although the stretching contributes to the advancement strength, it cannot be over-fired. The tensile inflation ratio should be controlled: the radial direction should not exceed 3.5 to 4.2, and the axial direction should not exceed 2.8 to 3.1. The wall thickness of the preform should not exceed 4.5 mm.

The blowing is carried out between the glass transition temperature and the crystallization temperature, and is generally controlled between 90 and 120 degrees. In this interval, PET is in a highly elastic state, which is quickly blow molded, cooled and shaped to become a transparent bottle. In the one-step method, this temperature is determined by the length of cooling in the injection molding process, so it is necessary to connect the two injections.

In the process of blow molding: stretching – one blowing – two blowing, the time of three movements is very short, but it must be well matched, especially the first two steps to select the overall distribution of the material, the quality of the blowing bottle. Therefore, it is necessary to adjust: stretching start opportunity, stretching speed, pre-blowing start and end chance, pre-blowing pressure, pre-blowing flow, etc., if possible, it is better to control the temperature distribution of the whole preform, in the preform The temperature gradient of the outer wall.

In the process of rapid blow molding and cooling, induced stress occurs in the bottle wall. For carbonated beverage bottles, it is resistant to internal pressure and has advantages, but for hot-filled bottles it is necessary to ensure that it is fully released above the glass transition temperature.

A plastic bottle is finished here.

Jilian Plastic Mould is a very professional and very reliable China Pet Bottle manufacturer. We can design tailor-made for you according to your needs, so what are you still hesitating? Come and contact us.