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What is blow molding during plastic products production?

Blow molding is a molding method for making hollow plastic products. At present, blow molding can produce various plastic bottles, jars and containers for packaging food, drink, cosmetics, medicines and other products.

● Primary process

Firstly, the semi-molten tubular plastic billet obtained by extrusion or injection molding of thermoplastic resin need to be placed in the opened mold. Next, the compressed air will be passed into the billet immediately to blow it after closing the mold, then the plastic billet will be close to the inner wall of the mold. Through the cooling and demoulding, workers finally can get the hollow products. Variety of plastic containers with different diameters and capacities can be obtained according to various shaped molds.


● Raw Material

There are many plastic materials suitable for this method, including polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polyester (PET) and so on. The most common blow-extruded plastic is high-density polyethylene (HDPE).

● Multiple Technology

According to the production method of billet, blow molding method can be divided into two categories, extrusion blow molding and injection blow molding. With the development, there are two new methods, multi layer blow molding and stretch blow molding. 

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