The screw of Single screw extruder mainly includes the following basic parameters:
① Screw diameter (Ds).

The manufacturer of Single screw extruder tells you that the screw diameter is used to indicate the size of the extruder, and it indicates the size of the extruder in a certain sense. The size of the screw diameter can generally be selected reasonably according to the cross-sectional size of the product, the processing performance of the material, and the required productivity and processing capacity, that is, the extruder model is selected. The manufacturer of Single screw extruder tells you that the screw diameter of the extruder in our country has been serialized. There are 30mm, 45mm, 65mm, 90mm, 120mm, 150mm, 200mm and other specifications. The more widely used screw diameter is 65～150mm. Generally, large-diameter screws should be used for products with large cross-sectional area, and small-diameter screws should be used for products with small cross-sectional area.
②L/D ratio (L/D).
The manufacturer of Single screw extruder tells you that the aspect ratio of the extruder refers to the ratio of the effective length of the screw to the diameter of the screw. The aspect ratio is another important parameter of the extruder. If the screw length-to-diameter ratio and the screw speed are considered together, it indicates the plasticizing capacity and plasticizing quality of the screw in a certain sense. The national standard series stipulate that L/D has 15, 20, 25, 30, etc., and the maximum can reach 43. The manufacturer of Single screw extruder tells you that you should choose an extruder with a moderate aspect ratio according to the properties of raw materials and production efficiency. If the aspect ratio is increased, as the length of the screw increases, the residence time of the plastic in the barrel is prolonged, and the material is plasticized more fully and uniformly, so the output and quality can be improved. However, this makes the processing and assembly of the screw and barrel more difficult, and the cost increases accordingly. The screw is easy to deform, and the gap between the screw and the barrel is easy to be uneven. Therefore, we should try our best to obtain high quality and high yield with a smaller aspect ratio. For example, when processing polyolefin and polyvinyl chloride materials, the ratio of screw length to diameter is 20 and 25.
③Compression ratio (ε).
The single screw extruder manufacturer tells you that the ratio of the volume of the first groove of the screw feeding section to the volume of the last groove of the homogenizing section is called the compression ratio. The size of the compression ratio has a great influence on the compactness of the product and the ability to remove the air contained in the material. It also affects the output of the extruder and the mechanical strength of the screw.
④The depth of the screw groove (h).
The manufacturer of Single screw extruder tells you that the depth of the groove is related to the thermal stability of the processed material. The depth of the groove in the compression section of the conventional screw is the most important, and it is a variable, expressed by h2. The depth of the screw groove of the feeding section is represented by h1, which is generally a fixed value. The manufacturer of Single screw extruder tells you that the groove depth of the homogenization section is represented by h3, which is generally a fixed value. The depth of the screw groove directly affects the plasticizing efficiency of the screw and the maximum pressure in production. For example, shallow spiral grooves are beneficial to plasticization, but the production efficiency is low; deep spiral grooves have a large extrusion volume, but the extrusion is not stable and the plasticization quality is poor.
⑤ Thread pitch (S).
The manufacturer of Single screw extruder tells you the distance between two adjacent threads, usually S=D.
⑥ Thread lift angle (Q).
The manufacturer of Single screw extruder tells you the angle between the spiral line and the vertical line of the screw center, generally Q=17°42′.
⑦Number of threads (P).
Under normal circumstances, the number of thread heads is 1.
⑧ Width of screw edge (e).
Refers to the width of the top of the screw edge along the axial direction, in mm.
⑨The gap between the outer diameter of the screw and the inner wall of the barrel (δ0), the unit is mm.