How to Control the Temperature of Twin Screw Extruder?

When using a twin screw extruder, many people are not sure about its temperature control, which can cause the product quality to be affected due to temperature not reaching the required level during production. So how should we control the temperature? The main control aspects include the temperature of the feeding section, melting section and homogenization section. This article will provide a detailed introduction to the control of the temperature of the twin screw extruder and the correct startup procedure.

Temperature control of the twin screw extruder

Temperature of the feeding section

The temperature needs to be lower at the inlet of the feeding section of the mini twin screw extruder to prevent resin from sticking and blocking the feeding port. Furthermore, the resin is continuously compacted in the feeding section, and air needs to be expelled in reverse from the feeding port. Depending on the structure of the twin screw extruder, the temperature of the feeding section is about 50-90℃. The temperature at the inlet is 50-90℃, and it should be equal to the melting point or viscosity temperature at the end, and the temperature should increase linearly in this section.

Temperature of the melting section

At the beginning of the melting section, the temperature needs to reach the viscosity temperature before melting. For crystalline resins, the viscosity temperature is equal to the melting point temperature. The temperature of the twin screw extruder needs to increase continuously to compact the resin and increase the melt layer, so that polymer molecules of different lengths and energy levels can be melted successively. Thus, after establishing the temperature at the end of the melting section, the temperature in other parts of this section should increase linearly.

Temperature of the homogenization section

This section is mainly used for melting homogenization and constant-temperature and constant-pressure output of the melt, and the temperature needs to be kept stable, or the temperature at the end of the melting section needs to increase slightly. For blowing thin film, the temperature of the die head section needs to be lower, but it cannot be lower than the viscosity temperature, which is conducive to the take-up and normal blowing of the twin screw extruder.

Technical points of the twin screw extruder

In the extrusion process, when the material changes from glassy state to molten state, it is necessary not only to maintain a stable balance between the heat required for plasticizing the material and the heat supplied to it but also to control the melting pressure. Due to the influence of the die resistance and the compression ratio of each section of the screw, the material is not in a constant pressure state. The compression ratio of different die heads and screw sections is basically balanced and stable, and cannot be changed. Therefore, consulting with a twin screw extruder manufacturer can be beneficial to ensure that extrusion is carried out with precision and maintain product quality.
Under the premise of constant extrusion speed, increasing or decreasing the material feeding speed will change the material capacity of the feeding section of the screw and maintain the material capacity of the exhaust section unchanged. Therefore, the melting pressure of the feeding section and the compression section will increase or decrease with changes in the compression ratio. Under the premise of constant material feeding speed, increasing or decreasing the extrusion speed will also change the material feeding capacity of the screw section. However, the material capacity of the exhaust section remains unchanged. Therefore, the melting pressure of the feeding section and the compression section of the twin screw extruder will also increase or decrease with changes in the compression ratio. The feeding speed will increase or decrease synchronously with the extrusion speed. As the material capacity of the feeding section of the screw is unchanged, the change in melting pressure is only caused by the increase or decrease in speed.