What Is the Blow Molding Process?

Blow molding is used to produce plastic bottles.

Blow molding is a method for making a variety of hollow plastic products. Molten plastic is extruded, in a tube shape, from a die, then a mold closes around it. The plastic is then inflated.

History

Blow molding first appeared late in the 1800s, but modern polyethylene bottle production did not commence until the early 1940s.

Types

The blow molding process can take four forms: reheat and blow molding, injection blow molding, stretch blow molding and extrusion blow molding. The machinery can vary significantly, though the major difference tends to be the point of plastic inflation.

Uses

The various processes are used to create a range of products, including bleach and milk bottles. Stretch blow molding is used in the production of PET (Polyethylene terephthalate) bottles, which are widely employed for carbonated beverages.

Plastics

The plastics used in the various blow molding processes can include HDPE (high density polyethylene), LDPE (low density polyethylene), PP (polypropylene), and PVC (polyvinyl chloride).