The working principle of the extruder

Principle of single screw extruder
The effective length of a single screw is generally divided into three sections. The effective length of the three sections is determined according to the screw diameter, pitch and screw depth, which is generally divided according to one-third of each.

The last thread at the material opening is called the conveying section: the material here is required not to be plasticized, but to be preheated and compacted under pressure. In the past, the old extrusion theory thought that the material here is loose. Later, it was proved that the movement of the material here is similar to that of a solid piston, so it is its function as long as the conveying task is completed.

The second section(extruder) is called the compression section. At this time, the volume of the screw groove gradually decreases from large to small, and the temperature should reach the plasticization degree of the material. The compression generated here is compressed from the conveying section 3 to one, which is called the compression ratio of the screw - 3:1. Some machines also change, and the plasticized materials enter the third section.

The third section(extruder) is the metering section, where the material maintains the plasticization temperature, but the melt material is accurately and quantitatively transported like the metering pump to supply the machine head. At this time, the temperature cannot be lower than the plasticization temperature, which is generally slightly higher.