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DB-1300-DB-1800
Three layer film blowing machine with horizontal haul off
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3DB-A
Three layer film blowing machine
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ABA
film blowing machine
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2DB-A
Two layer film blowing machine
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DB-B50/55/60/65
Single layer film blowing machine
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DB-A45-700/A50-900
Single layer film blowing machine with printer
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DB-350x2/450x2
T-shirt bag making machine
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DB-600-1000
Side sealing bag making machine
Temperature control of film blowing machine
In the process of film blowing, we often encounter the situation of inaccurate temperature control. So today, Debang Machinery has sorted out a very useful tutorial for your referenceThe extruder screw of the film blowing machine is divided into three sections: feeding section, melting section, and homogenization section.
At the end of the feeding section, when entering the melting section, according to the melting theory, its temperature should be the viscosity flow temperature. The viscosity flow temperatures of various film blowing resins are PP: 164-175℃, PE: 105-135℃, PA: 195-210℃.
1. Feeding section temperature requirements
At the entrance of the feeding section, it is hoped that the temperature is lower to prevent the resin from blocking the feed port. In addition, the resin is continuously compressed in the feeding section, and the air should be discharged from the feeding port backwards. According to the different equipment structures, although the feeding port is not electrically heated, the heat is transferred through the barrel, and the feeding port temperature is about 50-90 degrees. In this way, the feeding section temperature is determined. 50-90 degrees at the entrance, the end is equal to the melting point or viscosity flow temperature, and the temperature can be determined as a linear rise in temperature in this section.
2. Melting section temperature requirements
At the beginning of the melting section, the temperature reaches the viscosity flow temperature to melt. For crystalline resins, the viscosity flow temperature is equal to the melting point temperature. Then, the temperature needs to be continuously increased to continuously compress and increase the melting layer, so that the resin molecular chains are of different lengths and polymers with different thermal motion energies are melted one after another. Therefore, after the temperature at the end of the melting section is established, it can be determined that other parts of this section are linearly heated.
3. Homogenization section temperature requirements
In the homogenization section, the main thing is to re-melt homogenization and quantitative, constant pressure and constant temperature output of the melt. The temperature of this section can be kept constant, or the temperature at the end of the melting section can be slightly increased (about 2-5 degrees).
For blown film, the temperature of the die section is required to be lower, but not lower than the viscosity flow temperature, so as to facilitate film lifting and normal film blowing. When the melt comes out of the die, it must have a certain viscosity so as not to cause film breakage, film collapse and other phenomena. Generally, it is about 10-30 degrees lower than the end of the homogenization section. The temperature from the homogenization section to the die can also be regarded as an asymptotic temperature drop.
Key points for controlling extrusion temperature
1. Different types of resins have different process temperatures for blown film.
2. For the same type of resin, different models and melt indexes, the process temperature for blown film is different. The larger the index, the better the fluidity and the lower the temperature.
3. For the same type of resin, the process temperature for blown film of different thickness is also different. For thicker films, the process temperature can be higher.
4. The temperature of the die can also be higher, which is conducive to reducing viscosity and improving productivity.
Have you learned it after reading this tutorial?
Debang Machinery has been specializing in the production and manufacturing of blown film machines for more than ten years. New and old customers are welcome to order.
If you have any technical exchanges, you can also contact Debang Machinery.