Extruder Mechanical Principle

Principle of single screw extruder
Single screw is generally divided into three sections in effective length. The effective length of the three sections is determined by the diameter, pitch and depth of the screw, and is generally divided into one third each.
The last thread of the material port is called the conveying section: the material here is required not to be plasticized, but to be preheated and pressed. In the past, the old extrusion theory believed that the material here was a loose body. Later, it was proved that the movement of the material here is similar to a solid piston. Therefore, as long as the conveying task is completed, it is its function.
The second section is called the compression section. At this time, the volume of the screw groove gradually decreases from large to small, and the temperature must reach the degree of plasticization of the material. The compression generated here is from the conveying section three to one here. This is called the compression ratio of the screw - 3:1. Some machines also have changes. The plasticized material enters the third section.
The third section is the metering section. The material here maintains the plasticizing temperature. It just accurately and quantitatively transports the melt material like a metering pump to supply the head. At this time, the temperature cannot be lower than the plasticizing temperature, and is generally slightly higher.