Blow molding is a molding process used in the manufacturing industry to create hollow objects made of plastic. Like other molding processes, it involves the use of heated, liquid material that’s forced into a mold cavity under pressure. Blow molding is a special type of molding process, however, that leverages the properties of traditional glassblowing.
Blow molding follows the same principle as glassblowing. With glassblowing, a glassblower blows air across heated glass, thereby creating a hollow glass object. With blow molding, a machine blows air across heated plastic that’s placed on top of a mold cavity. The air forces the heated plastic to expand across the interior walls of the mold cavity.