NANJING LESUN SCREW CO.,LTD

Design of Extruder Screw

As one of the important parts of the main extrusion system of plastic extruder, plastic extruder screw design is very exquisite: not only plays the role of conveying plastics but also plays an extremely important role in the extrusion, plasticization and molding of plastics. Therefore, the rational selection of screw structure and parameters is an important link to obtain the ideal quality and output of products. In order to meet the different needs of plastic processing, the plastic extruder screw design will be somehow different, so there are many extruder screw types. Some common ones are as following: gradual change ( Isometric deepening screw/Isobathic varying-pitch screw), mutation change, torpedo head and etc. The selection of screw type is mainly determined according to the physical nature and of plastics and the technical specifications production of extruder.


1. In small plastic extruder screw design, such as φ45 extruder screw is a full thread type with Isometric deepening screw: the length and the diameter of screw is relatively small; mainly used to extrude insulation layer and sheath layer with small section; the extrusion speed is faster.


2. The softening of amorphous polymers is done at a relatively wide temperature; the isometric deepening screw is generally used. The melting temperature range of crystalline polymer is narrow, and isometric mutation screw is generally used.


3. Diameter of large screw is generally more than 150 mm, such as extruders  of φ150, φ200, φ250. The large screw adopts two types, one is isometric deepening screw, such as extruder of φ150, φ200; the other is the screw of isometric and isobathic, isometric deepening and deepening and varying-pitch which can be divided into three types, that is, such as φ250 extruder with the compression ratio between 2~3 and the ratio of length to diameter is about 15:1. It is mainly used to produce wire or cable insulation layer and sheath layer with large section.


4. Medium screw adopts full thread type with isometric but deepening gradient. Its LDR is larger than that of smaller screw, and the pitch of thread is the same with a varied depth from root to the up. The thread at the end of the screw is deeper and the thread at the root is shallow so that the plastic extrusion quantity is high but no influence to the screw strength and the extrusion speed is fast with great plastic effects. As far as the  plastic extruder screw design, the medium screw is the ideal one for the medium and small extruder to produce insulating layer and protection layer.

  • The Causes of Extruder Screw Abrasion and the Methods of Reducing Abrasion

    The Causes of Extruder Screw Abrasion and the Methods of Reducing Abrasion

    November 5, 2021The extruder screw is operated under high pressure, high temperature, high mechanical torque and high friction environment for a long time. Generally, the extruder screw has undergone surface nitridin...view
  • Repair Welding Plan after Extruder Screw Wear

    Repair Welding Plan after Extruder Screw Wear

    November 24, 2021The components of the extruder screw frequently suffer from wear and tear, and the cost of direct replacement is relatively large, and the economy is poor. Today we perform repair welding on the worn ...view
  • Correct Maintenance Tips for Twin Screws

    Correct Maintenance Tips for Twin Screws

    November 24, 2021When the material is processed, it is necessary to make the processed material obtain the energy required for the physical change and part of the chemical change. The twin-screw extruder is one of the...view
  • In November 2021, LESUN Sets Sail Again

    In November 2021, LESUN Sets Sail Again

    December 28, 2021In the past 20 years, LESUN has developed as fast as a torrential river.A team of less than 50 people has gone through all the difficulties and obstacles at the beginning of its establishment, and rid...view
top Inquiry