PET Plastic Bottle Blowing Process Introduction

PET blow molding bottles for sale can be divided into two types, one is a pressure bottle, such as a bottle filled with carbonated drinks; the other is a non-pressure bottle, such as a bottle filled with water, tea, edible oil, etc. This article mainly discusses the forming process of pressurized beverage bottles in cold bottles.


With the continuous advancement of science and technology and the scale of production, the PET bottle blowing machine is becoming more and more automated and the production efficiency is getting higher and higher. The production capacity of the equipment has been continuously improved, from the former production of thousands of bottles per hour to the production of tens of thousands of bottles per hour, which is an important factor for bottle blow molding machine manufacturers to take into consideration.

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Blow molding process

The important factors that affect the PET bottle blow molding process are preform, heating, pre-blowing, mold and production environment.


When preparing blow-molded bottles, PET chips are first injection-molded into preforms. It requires that the proportion of secondary recycled materials should not be too high (below 5%), the number of times of recycling cannot be more than two, and the molecular weight and viscosity must not be too low.

The quality of preforms depends largely on the quality of PET materials. Materials that are easy to inflate and shape should be selected and a reasonable preform forming process should be formulated. The quality of the preform determines the difficulty of the blow molding process. The requirements for the preform are purity, transparency, no impurities, no abnormal color, suitable injection point length and surrounding halo.


The preform is heated by a heating oven and its temperature is manually set and automatically adjusted.


Pre-blowing is an important step in the two-step bottle blowing method. It refers to pre-blowing while the stretching rod is lowered during the blow molding process, so that the preform takes shape. The pre-blowing position, pre-blowing pressure and blowing flow rate in this process are three important process factors. The shape of the pre-blow bottle determines the difficulty of the blow molding process and the quality of the bottle.

Auxiliaries and molds

Auxiliary equipment mainly refers to equipment to maintain the constant temperature of the mold. Mold constant temperature plays an important role in maintaining product stability. The mold is an important factor affecting the PET bottle blow molding process. The shape of the mold will reduce or increase the difficulty of process adjustment, such as the ribs, the arc of the transition zone and the heat dissipation condition at the bottom, which will affect the process adjustment


The quality of the production environment also has a greater impact on process adjustments. Constant temperature conditions can maintain process stability and product stability. PET bottle blow molding is generally better at room temperature and low humidity.


The PET bottle blow molding process is adjusted for the corresponding material. Energy-saving pet bottle blowing machine is popular among manufacturers. If the material is not good, the process requirements are very harsh, and it is even difficult to blow out a qualified bottle.






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