Blow Moulding Process

blow molding process, one kind manufacturing methods of thermoplastics. Using fluid pressure to inflate the hot parison closed in the mold into a hollow product. All those with a melt index of 0.04-1.12 are relatively excellent hollow blow molding materials, such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, thermoplastic polyester, polycarbonate, polyamide, cellulose acetate and poly. polyethylene are most commonly used among them.

There are three types of production process forms of Blow Molding Machine: extrusion blow molding process, injection blow molding process, and stretch blow molding process. The processes methods of different production are also quite different.

The extrusion blow molding process is to extrude the parison. When the parison reaches a predetermined length, the parison is clamped and positioned, then the head of the parison is formed or sized. Compressed air into the parison to inflate it close to the mold cavity, so that to form a product. After the product is cooled and shaped in the mold, the mold is opened to release the product, and deflashing the product.

2. Injection blow molding

The injection blow molding process is more suitable for the production of some large-batch, but small-volume products. Cosmetics, daily necessities, medicine and food packaging in the daily production are all use injection blow molding. The product has a uniform wall thickness, and there is less waste without joint line.

3.Stretch blow molding

Stretch blow molding is a process in which parison, stretching, and blow molding are completed in one machine line. The parison is semi-finished product in the production process. After cooling, the cold parison is reheated for stretching and blow molding. Oriented stretch blow molding after extrusion molding, maintain a certain stretching speed, orientate before blow molding, after stretching, transparency, impact strength, hardness and rigidity, surface gloss and barrier properties are all improved.

The production process of stretch blow molding is to control the temperature of the parison at a temperature lower than the melting point and use the principle of two-generation to increase the strength of the product.

The production process is to first inject the bottomed parison, continuously transport the material to the heating furnace, after heating to reach the stretching temperature, and then put it into the blow mold for axial stretching with the aid of a stretch rod, and finally blow molding.