What are the methods of PET bottle preform blow molding?

1. Extrusion blow molding

Extrusion blow molding is one of the most widely used methods for plastic packaging containers. The powder (or granular material) of thermosetting plastic is melted through an extruder, and then made into a hot-melt tubular parison according to a special material tube. When the parison exceeds the preset length, the parison enters the mold, the mold is closed, and then blow molded.
The characteristics of this molding method are: high manufacturing efficiency, balanced parison temperature, wide allowable range of shape, size and wall thickness of the hollow container, strong adaptability, high compressive strength of the blow molding process, simple machinery and equipment, and low engineering investment. However, the accuracy of the handicraft is not high. The inner cavity of the external thread will change with the change of the external thread on the surface. There is a patchwork seam at the bottom of the container.

2. Injection blow molding
Injection blow molding uses a plastic machine to inject the parison into the mandrel. After the parison is moderately cooled, the mandrel and the parison are fed into the blow molding tool. The blow molding tool presses the mandrel and the introduced air is closed and compressed so that The parison expands and produces the necessary handicrafts, and the goods are removed after being refrigerated and solidified.
The characteristics of this molding method: there are no seams in the crafts, no need for later renovation, high precision of the external threads and bottle stoppers, the inner cavity of the head and neck is on a smooth circle, the production capacity can be huge, there are few auxiliary machinery and equipment, and the compressive strength of the bottom of the product is High, low raw material consumption, uniform wall thickness, and high manufacturing efficiency. However, the investment in mechanical equipment projects is large, the production cycle is long, the requirements for practical operators are high, the appearance should not be too complex, and container specifications are limited, so it is suitable for manufacturing small and medium-sized high-precision containers.

3. Stretch blow molding
The molding method is to use a stretch rod to carry out radial stretching and then immediately carry out blow molding. In addition, during the molding process, biological macromolecules are orderly fixed on the walls of the artwork, thereby greatly improving the performance of the plastic container.
The characteristics of this molding method are: low defect rate, high manufacturing efficiency, easy control of net weight, high fracture toughness, improved rigidity, improved compatibility and smoothness of handicrafts, and good barrier and sealing properties , but the temperature control requirements for stretching are relatively high, and the investment in machinery and equipment is relatively large.

Post time: Nov-14-2023