Detailed introduction





Extruder screw planning considerations

  Extruder barrelThe plastic is built in and closely matched with the screw. For normal operation, the following important characteristics should be noted.
1. Screw barrel shall be straight.
2. The planning of the screw barrel should be able to enjoy the working pressure of the extruder. These pressures may be as high as 70-140MPa(10000-20000psi), and even higher in injection molding.
3. The inner wall surface of the screw barrel should be more wear-resistant than the extruder screw, because the screw is easier to replace than the screw barrel, and the reprocessing is cheaper than the screw barrel.
4. The support at the rear end of the screw barrel shall be a sliding support, which shall expand when the screw barrel is heated. Rigid support will cause bending of the barrel, which may cause severe damage to the screw and barrel.
5. In order to improve group transportation, the feeding section of the screw barrel can be slotted. The grooving and ungrooving section shall ensure outstanding cooling capacity to carry away the heat of high conflict and to prevent melting of the accumulated material in the groove. In addition, the groove should be tilted and the depth gradually shallower to minimize the timing of material hanging in the structure.
6. If there is no air vent, it should be offset, and the side wall of the opening is tangent to the inner wall of the screw barrel to reduce the timing when the plastic melt hangs at the front of the air vent, as shown in Figure 2.20. Compared with the traditional symmetrical exhaust port planning, it is easy to make the material continuously blocked at the bottom of the exhaust port. The opening of the vent can be planned to be skewed downwards to prevent cooling from flowing through the extruder barrel.