PET Blow molding machines use air pressure to form plastic into a desired shape. The plastic is heated and then forced into a mold cavity. The air pressure is then used to expand the plastic and form it into the desired shape. The plastic is then cooled and ejected from the mold.

The working principle of the PET blow molding machine is similar to that of blowing bubbles. After the plastic and the hopper enter the extruder barrel, they are forced towards the machine head by the screw as the screw rotates. Due to the resistance of the filter screen, splitter plate, and die at the machine head, as well as the gradual reduction of the capacity between the screw threads, the advancing material is subjected to great resistance, while being heated by the heat introduced from the material barrel; On the other hand, when plastic is subjected to forces such as compression, shearing, and stirring during movement, the friction between plastic and the barrel, screw, and plastic molecules will generate a large amount of heat. As the temperature of plastic in the barrel continues to rise, its physical state gradually changes from a glass state to a highly elastic state, eventually becoming a viscous flow state, and further fully plasticizing. Due to the continuous rotation of the screw, the plasticized plastic is extruded from the die of the machine head by equal pressure and amount, which is called a plastic product with a certain shape. After cooling and shaping, the extrusion molding work is completed.