Why does the blown film machine use the "blowing" method to make films?

The blown film machine uses the "blowing" method to make films. The key is that it can efficiently and continuously produce tubular films with excellent performance. After the plastic raw materials are melted and plasticized by the extruder, they are extruded from the annular die to form a vertically downward tubular melt blank. At this time, if the "blowing" method is not adopted, such as using a flat die to cast a film, although it is feasible, it is difficult to directly form a continuous and seamless tubular structure. The core technology of the blown film machine is to inject compressed air into the tubular blank so that it is continuously inflated and pulled upward like a huge balloon. It is this "blowing" action that makes the melt tube embryo quickly and evenly stretched, thinned, cooled and solidified under the combined action of longitudinal traction and lateral expansion force.

This "blowing" process gives the blown film machine unique advantages. First, by accurately controlling the blowing ratio (the ratio of the bubble diameter to the die diameter) and the pulling speed, the thickness and width of the film can be flexibly and continuously adjusted. Secondly, the film undergoes biaxial stretching (longitudinal and transverse) during the blowing process, and its polymer chains are oriented in these two directions, which significantly improves the mechanical properties of the final film, such as tear strength, puncture resistance and toughness, making it more uniform and strong. Finally, the whole process forms a stable film bubble that flows continuously upward, which is convenient for efficient cooling and winding, and has extremely high production efficiency. This "blowing film" capability of the blown film machine is particularly suitable for large-scale production of tubular film products such as packaging film, agricultural film, shrink film, etc. that require good comprehensive performance.

Therefore, the "blowing" method is not only the origin of the name of the blown film machine, but also the essence of its technology. It cleverly uses air pressure to achieve three-dimensional molding and directional stretching of molten plastics, while ensuring high production efficiency, giving the film structural integrity and balanced excellent physical properties, which is a core advantage that other film making methods cannot match.