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English
Views: 2 Author: Site Editor Publish Time: 2025-12-30 Origin: Site
How is the extruder screw connected and structured, what are its main functions during extrusion?
The extruder screw is attached to the drive linkage through the thrust bearing and rotates inside the barrel made of chrome-plated steel. Each turn of the helix is called a flight like the thread of a screw. The function of the screw is to convey the plastic resin through extruder by imparting mechanical energy to melt the polymer, mix the ingredients together, and build pressure to push resin through die.
The length/diameter (L/D) ratio is a very important characteristic of the screw, i.e., the ratio of the length of the flight portion of the screw to the inside diameter of the barrel. L/D is a measure of the capability of the screw to mix and melt materials. High L/D ratios indicate good mixing and melting capabilities, e.g., 45:1. The most common L/D is 20–30 for single-screw extrusion and 40–45 for twin-screw extrusion. Fig. 1.2 shows an example of a screw.
