The injection molding machine screw has the following characteristics:
1. The aspect ratio and compression ratio of the injection screw are relatively small;
2. The screw groove of the injection screw homogenization section is deep;
3. The feeding section of the injection screw is longer, and the homogenization section is shorter;
4. The head structure of the injection screw has a special form.
5. When the injection screw is working, the plasticizing ability and the melt temperature will change with the axial displacement of the screw.
According to its adaptability to plastics, injection molding machine screws can be divided into general-purpose screws and special screws. General-purpose screws, also known as conventional screws, can process most thermoplastics with low and medium viscosity, crystalline and amorphous plastics. Engineering plastics are the most basic form of screw. Correspondingly, there are special screws, which are used to process plastics that are difficult to process with ordinary screws. According to the screw structure and its geometric shape, it can be divided into conventional screw and new screw, conventional screw. Also known as the three-stage screw, it is the basic form of the screw. There are many types of new screw types, such as a split screw, a split screw, a wave screw, and a meterless screw.
The effective length of the thread of a conventional screw is generally divided into a feeding section (conveying section), a compression section (plasticizing section), and a metering section (homogenization section), which can be classified into a gradual type, a mutant type, and a general-purpose type screw depending on the nature of the plastic.
Gradient type screw: The compression section is long, the energy conversion is moderated during plasticization, and it is mostly used for plastics with poor thermal stability such as PVC.
The mutant screw has a short compression section and a sharp energy conversion during plasticization, and is mostly used for crystalline plastics such as polyolefin and PA.
General-purpose screw: The general-purpose screw with strong adaptability can adapt to the processing of various plastics, avoid frequent replacement of the screw, and help to improve production efficiency.
