Puhallusvalulla

Puhallusvalulla, often translated as "blow molding" in English, is a manufacturing process used to produce hollow plastic parts. It involves inflating a molten plastic tube, called a parison, into a mold cavity. The plastic then cools and solidifies, taking the shape of the mold.

The process typically begins with an extruder melting plastic pellets. This molten plastic is then forced through a die to form a parison, a hollow tube. This parison is then clamped between two halves of a mold, which is open at this stage. Once the mold closes around the parison, a blow pin or needle is inserted into the parison, and compressed air is blown into it. The air pressure forces the parison to expand and press against the inner walls of the mold. After a brief cooling period, the mold opens, and the finished hollow part is ejected.

Puhallusvalulla is widely used for producing a variety of products, including beverage bottles, detergent containers, fuel tanks, toys, and automotive components. The process is cost-effective for high-volume production and can create intricate shapes. The type of plastic used, such as polyethylene (PE) or polypropylene (PP), influences the properties of the final product, such as its flexibility, strength, and chemical resistance. There are two main variations of blow molding: extrusion blow molding, described above, and injection blow molding, which involves injecting plastic into a mold to form a preform before blowing it.