What Are the Commonly Used Screws?

Usually screw elements can be divided into ordinary type, gradual type, mutation type, mixing type, separation type, split type and various barrier type, pin type, DIS split type and exhaust type, etc. The number of screw heads can be divided into Single head or variable head, etc.

For general plastics without flame retardants, they can be processed with ordinary general-purpose screws, and only need to choose different diameters according to different melt viscosities. If it is plastic with special performance, special product or plastic with special particle shape, special screw must be used. For a certain kind of plastic, the general-purpose screw is not as good as the special screw in terms of plasticization and power consumption.

The following is the introduction of various special products and special extruder screw elements manufactured for special needs.

1. PC special screw components

Pc is a high-viscosity non-crystalline plastic with poor fluidity, easy to degrade when heated for a long time, large feeding torque, difficult to melt, easy to block, requires high material temperature and high pressure injection, narrow material temperature adjustment range, and is inferior to PMMA in manufacturability.

2. PMMA special screw element

PMMA is a high-viscosity non-crystalline plastic, with strong properties, large feeding torque, difficult to melt, easy to block, shear sensitive, easy to degrade, slightly poor in fluidity, must be injected with high material temperature and high pressure, and the material temperature adjustment range Wide and good craftsmanship.

3. PVC special screw elements

PVC plastic can be divided into granular and powder, which is very sensitive to temperature, easy to decompose, high viscosity and strong corrosiveness. The design of the screw has two characteristics: the surface must be chrome-plated; there is no rubber separation ring and glue separation meson.

The screw has good plasticization, less shear heat and acid corrosion resistance. Because there is no rubber ring, it cannot be used for low-viscosity plastics and products with accurate injection speed pressure classification.

4. Special screw elements for PU and TPU

Designed for PU shear sensitivity, easy to overheat, strong adhesion and characteristics, the surface is electroplated with hard chrome, smooth feeding, high plasticizing efficiency and low temperature rise. Soft rubber, EVA foam type special screw with low shear, high conveying efficiency design, hard chrome plating on the surface.

5. PPO special screw elements

PPO is an amorphous material, difficult to melt, easy to block, sensitive to shear, and easy to degrade. It is recommended to use double alloys to improve wear resistance and corrosion resistance. Grade C is sufficient. The screw feeds smoothly and generates stable pressure.

6. Special screw elements for PBT+GF

PBT is a saturated resin, semi-crystalline material, with high melting degree, rapid crystallization, fast curing, easy decomposition, sensitive to pressure and need to add glass fiber. Double alloys must be used to improve wear resistance. According to the heating amount, there are three engineering grades of C, B and A to choose from, and the pressure generated by the screw is stable. It has good effect on molding PBT+GF, PA+GF and other crystalline low-viscosity common engineering plastics.

In terms of production specifications, LESUN not only provides general extruder screws and standard twin-screw extruder accessories produced by manufacturers, but also provides design and manufacturing services for special extruder accessories according to customer requirements. At the same time, we also provide surveying and mapping business and processing business of accessories for major extrusion press companies. If necessary, welcome to consult.

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