What does mineral water beverage bottle use to blow molding
Different blow molding methods have different advantages in processing different products due to differences in raw materials, processing requirements, production and cost.Detailed blow molding process can be referred to the literature.The characteristics of blow molding are introduced from macroscopic view.Blow molding of hollow products includes three main methods: extrusion blow molding: mainly used for unsupported blank processing;Injection blow molding: mainly used for the metal core support mold blank processing;Stretch blow molding: it includes two methods: extruding one stretch blow molding, injection one stretch one blow molding. It can process biaxial oriented products, greatly reducing production cost and improving product performance.In addition, there are multilayer blow molding, press blow molding, dip coating blow molding, foaming blow molding, three-dimensional blow molding and so on.However, 75% of blow molding products are molded by extrusion, 24% by injection, and 1% by other blow molding products.Of all blow molding products, 75% are bidirectional stretch products.The advantages of extrusion blow molding are high production efficiency, low equipment cost, wide selection of mold and machinery, but the disadvantages are high scrap rate, poor recycling and utilization of waste materials, the thickness control of products and the dispersibility of raw materials are limited, and the trimming operation must be carried out after forming.The advantages of injection and blow molding are that no waste is produced in the process of processing, the wall thickness of products and the dispersal of materials can be well controlled, the fine neck product has high forming precision, the product surface is smooth and clean, and the small batch production can be carried out economically.The disadvantage is the high cost of forming equipment, and to a certain extent only suitable for small blow molding products.The process conditions of hollow blow moulding require that the compressed air of medium blank of blow moulds must be clean.The air pressure of injection blow molding is 0.55 ~ 1MPa.The extrusion blow pressure is 0.2l ~ 0.62mpa, while the stretching blow pressure is often up to 4MPa.In the process of plastic solidification, low pressure leads to low internal stress, uniform stress distribution, and low stress can improve the tensile, impact and bending properties of the product