What are the functions of the extruder screw?

Update:21-07-2018
Summary:

The rotation of the extruder screw in the barrel is car […]

The rotation of the extruder screw in the barrel is carried out under the high temperature and high pressure and large twist. Because it strongly pushes the material forward during the rotation, it also has to bear strong friction and plastic decomposition of corrosive gas. Erosion, so the material of the extruder screw must have high mechanical strength, withstand large torque and high deformation under high temperature and high pressure.

During the rotation of the extruder screw, the plastic is mainly sheared and plasticized by the screw edge, and the plastic is pushed forward. Therefore, the screw edge is subjected to huge shear stress and friction force, and the screw edge is operated due to long-term operation under severe conditions. Wear, the screw edge becomes smaller, and the gap with the barrel increases, which leads to a decrease in the amount of plastic extrusion. In severe cases, plastic reflow occurs, and the plasticizing effect is reduced, and the grain and productivity are seriously degraded.

The process of melt extrusion is to take the premixed material from the feeding port into the extruder barrel. The first section of the barrel is the feeding section. The material will not melt at this stage. The material is taken along with the screw drive of the extruder. The second section is the compression section. The section is the heating stage, the material begins to melt, the friction between the materials increases, and a high-viscosity is formed. The third section that continues to drive with the screw of the extruder into the high shear is the homogenization section. It is very effective in separating pigment aggregates for the purpose of full dispersion.

At present, the extruder equipment used in powder coatings is used in twin extruder screw extruders, single extruder screw extruders and star extruder screw extruders, although the type of extruder, The internal structure is different, but the design purpose is the same, that is, the material is evenly dispersed. Therefore, Qingdao Hetai Plastic Machinery believes that the quality of the extruder directly determines the degree of dispersion of the material.

Related Product: screw of blow molding machine