What are the exhaust forms of extrusion blow molding molds? What are their characteristics?

Generally, the exhaust methods used in blow molds mainly include exhaust in the mold cavity, exhaust on the parting surface, vacuum exhaust and exhaust in the thread groove of the mold neck. Exhaust in the mold cavity: In order to discharge the air in the blow mold as quickly as possible during the production process, it is necessary to set up an exhaust system in the mold cavity wall. Exhaust on the parting surface: The parting surface is the main exhaust part of the blow mold. After the mold is closed, as much air should be exhausted as quickly as possible. Vacuum exhaust: If the discharge speed of air trapped in the mold cavity is lower than the inflation speed of the parison, an air pressure greater than the inflation pressure of the parison will be generated between the mold cavity and the parison, making it difficult for the inflated parison to contact the mold cavity. Exhaust in the thread groove of the mold neck: The air trapped in the thread groove of the mold neck is difficult to remove, which can be solved by opening an exhaust hole.