Blow molding

Process

Blow molding
Blow molding is a manufacturing process that is used to produce hollow plastic parts. There is a wide variety of materials that can be used in this process, including, among others, high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), poly (vinyl chloride) (PVC), poly (ethylene) terephthalate) (PET), copolyester and TPV.
Basic process
The basic process begins with melting the thermoplastic and extruding it through a die head to form a hollow tube called a parison. The parison is held between two mold halves, which close around the compressed air is inflated with compressed air until it conforms to the internal shape of the mold cavity. Finally, the molds are opened and the finished piece is removed. Basically, there are three types of blow molding used to form the parison. In extrusion blow molding, the plastic is melted and extruded using a rotating screw to force the melt through a die head that forms the part. Injection blow molding is a partial injection molding and partial blow molding, where the molten plastic is injection molded around the central pin and then the central pin is transferred to a blow molding station to be inflated. There are two stretch molding techniques. In the process of a stage, the preform is molded by injection and then transferred to the blow mold where it is blown and ejected from the machine. In both process of the stage, the preform is injection molded, stored for a short period of time and blown into the container using a reheat blowing machine.