What is the stretch blow molding process?
Stretch blow molding is a two stage process similar to injection blow molding. First, a test tube like preform parison (pictured above) is injection molded in-house, or the preform parison can be purchased from an outside vendor. The neck of the preforms is fully finished (with threads) but the diameter and length of the body are much smaller than the final product. The thermoplastic preform then undergoes a reheat process (usually via infrared heaters) and is stretched and blown against the mold. This process is sometimes referred to as “reheat and blow molding†process, RHB for short. Below is a step by step diagram of the stretch blow molding process:
