How to control the temperature of a film blowing machine

For those who frequently use film blowing machines, film blowing machines are undoubtedly familiar. However, there is one issue that film blowing machine operators often find perplexing: what is the appropriate temperature range for controlling the film blowing process? Since temperature levels can directly or indirectly impact the quality of the film produced by the machine, it is essential to maintain proper temperature control.

　　At the beginning of the melting section, the temperature must reach the viscous flow temperature for melting. For crystalline resins, the viscous flow temperature is equal to the melting point temperature. As the resin is continuously compressed and the melt layer thickens, the temperature must be gradually increased to ensure that resin molecules of varying lengths and different thermal motion energies melt sequentially. Once the temperature at the end of the melting section is established, it can be set such that the temperature increases linearly across other sections of the same segment.

　　At the inlet of the feeding section, a lower temperature is desired to prevent resin viscous flow from blocking the feed port. Additionally, as the resin is continuously compressed in the feeding section, air must be expelled backward through the feed port. Depending on the equipment design, the feed port may not be electrically heated, but heat is transferred through the barrel, thereby determining the temperature of the feeding section. The temperature at the inlet is 50–90°C, and at the end, it equals the melting point or viscous flow temperature. Along this section, the temperature can be set to increase linearly in proportion.

For the control of extrusion temperatures in film blowing machines, the key points are:

Different types of resin require different process temperatures for film blowing;

For the same type of resin, different grades and melt indices result in different process temperatures for film blowing. Resins with higher melt indices have better flowability and require lower temperatures.

　　For the same resin, different film thicknesses require different process temperatures. When processing thicker films, the process temperature can be slightly higher, and the die temperature can also be slightly higher, which helps reduce viscosity and improve production efficiency.

　　That's all we have to share about controlling blow molding machine temperatures. We hope this information is helpful to you!