The difference between blow molding process and injection molding process

- Feb 27, 2019-

Blow molding products are hollow;Injection molding because there is injection molding mouth, so the molding of the product will be a small part of the fast do not want, youdao process will cut it, but if carefully observed or can be found;


Injection molding is a method in which thermoplastic or thermosetting molding materials are uniformly plasticized in the heating cylinder and then pushed into the closed mold cavity by the plunger or moving screw.


Injection molding is suitable for almost all thermoplastics.In recent years, injection molding has also been successfully used to form certain thermosetting plastics.Injection molding molding cycle is short, the quality of molding products can be from a few grams to dozens of kilograms, a molding complex shape, precise size, with metal or non-metal insert molding products.Therefore, this method has strong adaptability and high production efficiency.


Blow molding: by means of gas pressure, the hot mold billet closed in the mold is blown into a hollow product, or the tube billet is blown into a tube film without a mold.The method is mainly used in the manufacture of various packaging containers and tubular membranes.


All melt index of 0.04~1.12 are relatively good blow molding materials, such as polyethylene, polyvinyl chloride, polypropylene, polystyrene, thermoplastic polyester, polycarbonate, polyamide, cellulose acetate and polyacetal resin, among which polyethylene is the most widely used.


Injection blow molding: by injection molding method, the plastic is first made into a bottom-type blank, and then the blank is moved into a blow molding mold to be blown into a hollow product.


Extrusion blow molding: it is to use the extrusion method to first make the plastic into a bottom-type billet, and then move the billet into a blow molding mold to blow hollow products.


Stretch blow molding: stretch blow molding is a kind of biaxial directional stretching blow molding, the method is the first will also carry out longitudinal stretch, and then blow with compressed air to reach transverse stretch.Stretch blow molding can greatly improve the transparency, impact strength, surface hardness and rigidity of products. It is suitable for the blow molding of polypropylene and polyethylene terephthalate.


Film blowing: a method of forming thermoplastic films.By means of extrusion method, the plastic is first extruded into a tube, and then continuously expanded to a certain size with the help of air blowing into the tube, and then folded and wound into a double-layer flat film after cooling.