Blow molding classification

Hollow blow molding is divided into injection blow molding, extrusion blow molding and stretch blow molding, injection blow molding is made of plastic bottom billet by injection molding method, and then the billet into the blow molding mold for blow molding.  In the process of extrusion blow molding, the tube billet is directly extruded by the extruder and hung in the pre-separated cavity installed just below the machine head.  When the drooping billet reaches the specified length, the die is closed immediately, and the tube billet is cut off by the cut of the die.  From the mold parting surface through the hole into the compressed air, the billet blowing close to the mold wall and forming;  Keep pressure, and take out the products after cooling and finalizing in the mold cavity.  
 
There are many kinds of thermoplastic used for hollow blow molding. The most commonly used raw materials are polyethylene, polypropylene, polyvinyl chloride and thermoplastic polyester, etc., which are commonly used to form various liquid packaging containers, such as various bottles, barrels, cans and so on.  Distinguish between extrusion blowing and injection molding blowing (including injection pull blowing) method is to observe the bottom of the product, the bottom has a navel like injection molding point is injection molding blowing or injection pull blowing products, the bottom has a mold line is the extrusion blowing products.