Contrary to injection molding, blow molding can achieve thin wall, non-symmetrical wall geometry of a part. Injection molded parts typically cannot have undercuts on the inside of a vessel, where as blow molding can achieve much more difficult undercuts in parts since there is not a metal core that needs to be removed from the part before ejection.
A parison is injection molded that will have the overall part weight of the finished blow molded part. This parison looks like a test tube with thick walls. This parison is then brought into a reheat blow molding machine. The preform is heated above the glass transition temperature, then high pressure air is blown into the vessel until the outter walls of the parison are formed against the metal blow mold. Blow molding can achieve shapes like water bottles, 2 Liter bottles, spice containers, shampoo bottles, contoured walled beer glasses, milk jugs and many more. Having injection molding and blow molding in the same facility really opens up our opportunities as we can provide a complete finished good for our customers and not just a portion of the components.