7. Blow molding
Blowing (expansion film) plastic (or hollow blow molding) refers to a molding process in which a hot thermoplastic parison or sheet in a closed mold is inflated into a hollow product by means of fluid (compressed air) pressure.
A plastic container produced in this way. Such as various bottles, squares, round or flat barrels, fuel tanks, etc. have been widely used. Newly developed various industrial parts and daily-use products, such as double-walled box-shaped products, L-ring large drums, pallets, surfboards, seat backs and desks. As well as front spoilers, belt covers, instrument panels, air conditioning ducts, etc. for automobiles, they have been applied in practice. The processed materials have evolved from household plastics to engineering plastics. Blow molding has now become one of the important molding methods in plastic processing.
But the basic steps of the blow molding process are:
(1) molten material;
(2) forming a molten resin into a tubular or parison;
(3) sealing the hollow parison blow mold;
(4) inflating the in-mold parison;
(5) cooling the blow molded product;
(6) taking out the product from the mold;