What is Blow Molding
Blow molding is a manufacturing method widely used in the plastic industry to create strong, hollow thin-wall containers. Some examples of products commonly created through this process are cases and containers like plastic beverage bottles, plastic drums and fuel tanks. A typical blow molding process involves melting plastic into a hollow tube, known as a parison, placing the tube between to halves of a mold, and pumping pressurized air into the parison until it expands to fit the form of the mold. The two halves of the mold then separate and the finished container is released.
Blow molding any type of container requires a preformed piece of plastic called a parison, a heated hollow thermoplastic tube. This parison is usually extruded from a plastic injection mold placed very close to the blow molding machinery. The warm parison looks like an upside down plastic test tube, with a preformed collar and threads for the cap at the bottom. The parison is mechanically loaded onto a stand and two sides of a bottle-shaped metal mold come together around it. The difference between the three processes lies at this point of the process. The molded plastic will be left to cool and harden. Once released from the mold, the plastic part can be post-processed to have the holes rimmed or residues trimmed.