Water or suitable liquid is added to the raw material powder and stirring is continued. The agitated material is extruded from the perforated head or wire mesh with high extrusion pressure.
Usually the material is placed in a cylindrical container and the material is extruded with a screw. After the inverter technology is used, the pressure can be controlled so that the most suitable linear speed can be selected.
Single screw extruder principle
The single screw is generally divided into three sections in the effective length, and the effective length of the three sections is determined according to the screw diameter and pitch screw depth, which is generally divided by one third.
The last thread of the material mouth is called the conveying section: the material here must not be plasticized, but it must be preheated, pressed and crushed. In the past, the old extrusion theory thought that the material was loose, and later it was proved that the material was actually The solid plug, which means that the material is squeezed like a plug, is the same as the plug, so as long as the completion of the delivery task is its function.
The second section is called the compression section. At this time, the volume of the screw groove gradually becomes smaller, and the temperature must reach the plasticization degree of the material. Here, the compression is generated by the conveying section three, and here it is compressed to one. This is called the compression ratio of the screw. At 3:1, some machines also changed, and the plasticized material entered the third paragraph.
The third section is the metering section, where the material maintains the plasticizing temperature, just as the metering pump does as accurately and quantitatively conveys the melt material to feed the head. At this time, the temperature cannot be lower than the plasticizing temperature, which is generally slightly higher.