There are many different industrial applications that help mass-produce items. Blow molding is a manufacturing process that forms hollow plastic parts. There are three main variations of blow molding: injection, extrusion, and injection stretch blow molding.
The specifications for any blow molding machines determines the size and type of mold that can be used. These specifications include the extruder’s melting capacity in pounds of kilograms per hour and the plastic melt temperature. Another specification is the clamp force. The clamp force is the maximum force in tons that the clamp can exert while keeping the mold halves closed.
Extrusion blow molding:
Extrusion blow molding is a simple process that starts with melting down plastic to form a parision. The parison is then forced into a cooled, metal mold and air is blown into it. The air inflates the parison into the shape of a hollowed out cylinder, container, or part. Once the freshly molded part has cooled, the mold is opened and the piece is ejected. Extrusion blow molding can be preformed in two different processes: intermittent or continuous. Continuous extrusion blow molding is when the parison is continuously extruded from the mold and the different parts are cut away. In the extrusion blow molding process, plastic is heated until the plastic becomes a viscos fluid. Excess plastic is removed with a knife, and is subsequently discarded. One of the most common items are blow molded cases, and so you will find a good deal of custom carrying cases made this way.
Injection Blow Molding:
Injection blow molding is used to created hollow glass and plastic objects in large quantities. During the injection blow molding process, a polymer is molded into a core pin, where it is subsequently rotated to a blow molding station, inflated, and then finally cooled. This is the least commonly used blow molding typology and is most commonly used to create small single serve bottles.
Stretch blow molding:
During the stretch blow molding process, the plastic is molded into a preform, by using the injecting molding process. The preforms are created with the necks of bottles that have threads on one end. All preforms are heated with infrared heaters to a point where they surpass their glass transition temperature. After, they are blown into metal blow molds by using a high-pressured air.