How does the exhaust screw effectively remove gas during the extrusion process?

1. Design features of exhaust screw
Exhaust channel or notch: The exhaust screw is designed with special exhaust channels or notches, which allow gas to escape from the material during the rotation of the screw. Their position, number and shape are carefully designed to ensure that the gas can be discharged smoothly while avoiding material leakage.
Screw structure: The pitch, groove depth and other parameters of the exhaust screw may be adjusted according to the material characteristics and extrusion requirements to optimize the exhaust effect.

2. Working principle
Material melting and gas release During the extrusion process, the material enters the barrel under the push of the screw and is subjected to high temperature and high pressure, gradually melting. As the material melts, the gas in it is gradually released and moves to the low-pressure area through the exhaust channel or notch.
Gas discharge: When the gas reaches the exhaust channel or notch, it is discharged smoothly due to the rotation of the screw and the pressure difference in the barrel. The exhausted gas escapes through the exhaust hole on the barrel or is extracted by a vacuum pump, depending on the design of the extruder.

3. Influencing factors and optimization measures
Material characteristics: The moisture content, volatile matter content and other characteristics of the material will affect the exhaust effect. Therefore, when selecting and using the exhaust screw, it is necessary to consider the characteristics of the material and make corresponding adjustments.
Extrusion speed: Too fast extrusion speed may cause the gas to not be fully released, thus affecting the exhaust effect. Therefore, it is necessary to control the extrusion speed to make it suitable for exhaust.
Exhaust port design: The position, number and size of the exhaust port have a great influence on the exhaust effect. Reasonable exhaust port design can ensure smooth gas discharge while avoiding material leakage.
Screw maintenance: Regularly clean the exhaust port and screw surface to prevent dirt and particles from clogging the exhaust channel and affecting the exhaust effect.
Check the wear of the screw and replace the severely worn screw in time to ensure the stability of the extrusion process and the exhaust effect.