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PE protection film is a common plastic product in our life. It is produced by the methods of calender, extrusion and blow molding. The way to blow plastic film is to melt the raw material through the extruder to melt the raw material into thin tube, and then blow it in compressed air and make the film products by cooling and setting.

The main raw materials used for blown molding film are LDPE, HDPE, LLDPE, EVA, PVC, PP, PS, PA, etc.

Molding process of polyethylene blown plastic film

After extruding, the raw material is formed by tube forming and then bulging, cooling, traction and coiling.

In the process of blow molding film forming, there are three ways of flat blowing, top blowing, and bottom blowing according to the different direction of extrusion and traction. This is the common molding process, and there is a special blow molding method, such as the top extrusion blow method.

1. Flat extrusion

The method is to use a right angle head, that is, the head of the extruder is perpendicular to the extruder. The extruding tube is broken upward. After pulling to a certain distance, it is clamped by the character plate. The compressed air introduced by the bottom is blown into the bubble tube, and the lateral size of the compressed air is controlled by the compressed air volume, and the longitudinal direction is controlled by the speed of traction.  The blown film can be obtained by cooling and setting the size of the bubble tube. The main plastic varieties suitable for top blowing are PVC, PE, PS and HDPE protective films.

Two, flat extrusion and down blowing

The method uses a right angle head. The flow of the bubble tube from the bottom of the machine is called the flat extrusion. This method is especially suitable for the small viscosity material and the plastic film with high transparency. Such as PP, PA, PVDC (partial two chloroethylene).

Three, flat extrusion and flat blowing

This method uses the flat head of concentric extruder screw and the process of flat extrusion and flat blowing on the same horizontal surface of the tube and the center line of the machine. This method is only suitable for the products of blowing small caliber thin film, such as LDPE, PVC and PS film, and the flat blow method is also suitable for the production of heat shrinkable film.

The advantages and disadvantages of the above three process processes are all compared with the advantages and disadvantages of the process flow. The advantages and disadvantages of the process flow are flat on the cooling tube, the traction stable area is small, the operation is easy to be produced, the thickness of the protective film is high and the high cost of the plastic is not suitable for the protection of the film cooling. The production efficiency is low and flat, it is beneficial to protect the film cooling, the high efficiency of production and the high processing flow of plastic extruder from the ground is higher. The operation is not convenient to produce the thin protective film flat extrusion head as the center, the structure is simple, the protection film thickness is more convenient to operate, the film blowing ratio is easy to be easy to blow up. It is not suitable to process the protective film with large relative density and large diameter. The area of the bubble tube is relatively slow, and it is not suitable for processing plastic with high fluidity.