Blow Molding technology for PET bottles

Blow molding, a process where hollow plastics are formed, has revolutionized the production of PET bottles. This technique utilizes thermoplastic materials such as LDPE, HDPE, PET, PP, and PVC to create a variety of blow molded products.

In extrusion blow molding, raw plastic pellets are fed into a hopper, descending into a screw conveyor. As the screw pushes the pellets forward, they're heated and melted into a molten state, known as parison. This preform tube, once molten, is then forced through an orifice into a mold. Air is blown into the parison, followed by a cooling process to solidify the shape.

Injection blow molding, on the other hand, is a two-phase cyclic process. It begins with melted plastic being injected into a steel mold cavity to form the parison. This preform is then transferred to a mold where it undergoes final curing. The process involves a hopper, an Archimedean screw, and a heating element, culminating in the mold cavity where the product is formed and extracted.

Stretch-blow molding is the preferred method for PET bottles. It starts with creating a test-tube-like preform, which is then stretched and blown into its final shape. The preform's neck is already complete, with the body's diameter and length smaller than the finished bottle.