1.The compression ratio, aspect ratio, and screw config […]
1.The compression ratio, aspect ratio, and screw configuration of the screw should be selected according to the plasticizing temperature conditions, stability, viscosity, and melt;
2.The screw should be selected according to the type of material being extruded. If the raw material is a crystalline polymer, a screw with the same pitch change type should be used. Such raw materials are PE, PP, PA, CP, POM and so on. If the material is a non-crystalline polymer, a graded screw with equal pitch should be used. Such raw materials are PVC, PS, ABS, PC, PSC and so on.
3.For the extruder screw used to extrude only one kind of raw material, a special type Injection Molding Machine Screw should be selected. If the extruder is to extrude many different kinds of raw materials, it is necessary to consider the use of spare screws for extrusion molding of different plastics or general-purpose screws.
4.The depth of the thread groove should be chosen to match the resistance of the mold and the volume of the flow channel. When the flow path volume of the forming mold is small and the resistance is large, the thread groove depth of the screw should be shallower; on the contrary, it can be deeper.