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The production process of film blowing machines

Update time : 2020-11-09

Source : Zhejiang Deguang Machinery Co.,Ltd

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The production process of film blowing machines

PE film blowing machine supplier


What is the production process of the film blowing machine? What aspects should we pay attention to in the production process of the film blowing machine? Next, we will give you a detailed introduction.


Blown film is made through a ring mold, so the extruded hollow plastic tube film is often called "bubble". Air pressure expands the hollow tube membrane to form the ideal size. Although the tube film can be extruded horizontally or downward, it is usually extruded vertically upward. Cooling is accomplished by blowing cold air to the film through a cooling ring directly installed at the die outlet. Some have both internal and external cooling methods. Sometimes the tube film is rapidly cooled and preheated before being stretched with air pressure.

The size of the film depends on the output of the film blowing machine and compressed air pressure. "Blow-up ratio" is the ratio of the diameter of the blown film to the die diameter. Although compressed air can enter through the wall of the bubble, the wall can be automatically sealed, and once it is sealed, it will operate stably. If there is a slight air leakage, the resulting bubble becomes smaller.

The passage through the top of the film is various guiding devices. Including air ring and guide roller. When the film is sufficiently cooled, the bubble is clamped by the plywood and rollers, rolled up, cut or not cut, folded or otherwise processed. Therefore, this process can be used to produce bubble tubes as well as flat films.

Once the blown film process starts to run, there is almost no waste produced because there is no edge effect similar to flat extruded film. However, it is quite difficult to make the production line run normally. Therefore, more waste is generated when it is first started. Compared with the flat extrusion film production line, the blown film production line has higher output and is more economical when started. Therefore, blown film is known for its high output. It is estimated that about 90% of polyethylene film is produced in this way.

In terms of film transparency and uniformity, blown films are inferior to flat extrusion films. Mainly due to the slow cooling rate of the blown film process. In terms of transparency, slow cooling causes a large degree of crystallization and the formation of large crystals, resulting in film blurring. Uneven cooling results in huge changes in film thickness. Because even a little bit of eccentricity and a little defect at the opening of the die will cause significant unevenness in the shape of the roll film, the general method is to rotate the die during extrusion, so that the change in thickness is instantaneous, and the thickness is uniform. Roll film. In some cases, the thickness of the film varies by ±15%, although the variation range of ±7% is more common. Of course, it is also possible not to rotate the mold, but to rotate the tube film during winding.

In blown film, the film can usually be stretched between a mold and a nip roll to form machine direction orientation. The film is also oriented in the transverse direction when the bubble is expanded. Therefore, the film is bidirectionally oriented, and a balance of orientation is produced by biaxial stretching. Through further processing of the down-flow film blowing device, auxiliary orientation can be produced. Some blown film production lines use both extrusion and feeding die heads, each using its own film blowing machines.

Deguang Machinery is a PE film blowing machine supplier and manufacturer. We understand the production process of film blowing machines. If you want to know the details, you can contact us.

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