Hollow blow molding is a secondary forming technology that utilizes gas pressure to inflate a rubber-like parison enclosed within a mold cavity into a hollow plastic product. It is a widely used method for producing hollow plastic items. Depending on the manufacturing method of the parison, hollow blow molding can be further classified into extrusion blow molding, injection blow molding, and stretch blow molding.
- Extrusion Blow Molding: In this process, a tubular parison is extruded from an extruder and, while still hot, is clamped and sealed at the bottom within a mold cavity. Then, compressed air is introduced into the tube to inflate it into the desired hollow shape.
- Injection Blow Molding: Here, the parison is first formed by injection molding and left on the core pin of the mold. After the blow mold is closed, compressed air is blown through the core pin to inflate the parison, shaping it into the hollow product. Upon cooling, the product is ejected from the mold.
- Stretch Blow Molding: This method involves placing a heated parison, at its stretching temperature, into a blow mold. The parison is then stretched longitudinally using a stretching rod and inflated transversely with compressed air, resulting in a hollow product with enhanced properties.
Applications of Hollow Blow Molding:
Hollow blow molding is predominantly employed in the production of various hollow plastic products, including bottles, packaging drums, spray bottles, fuel tanks, cans, toys, and numerous other items.
