The characteristics of the gradual extruder screw: the compression section is longer, accounting for 50% of the total length of the screw, the energy conversion is gentle during plasticization, and it is mostly used for PVC and other plastics with poor thermal stability.
The characteristics of the abrupt extruder screw: The compression section is short, accounting for about 5% to 15% of the total length of the screw, and the energy conversion is more intense during plasticization. It is mostly used for polyolefin, PA and other crystalline plastics.
General-purpose extruder screw features: relatively strong adaptability, can be adapted to the processing of a variety of plastics.
In general, the extruder screw can be divided into feeding section, compression section, and homogenization section (also called metering section).
Description of feeding section: The screw groove of the extruder in this section has a fixed depth, and its function is to be responsible for preheating and plastic solid conveying and pushing. It must be ensured that the plastic begins to melt at the end of the feed section.
Compression section description: The screw thread of the extruder in this section gradually shrinks, and its function is to melt, mix, shear, compress and pressurize the plastic raw materials. The plastic will be completely dissolved in this section and the volume will be reduced. The design of the compression ratio is very important.
Homogenization section description: the screw groove of this section of the extruder has a fixed groove depth. Its main functions are mixing, melt conveying, and metering. It must also provide sufficient pressure to maintain a uniform temperature of melt and stabilize the flow of molten plastic.
1. 38CrMoAla;
2. SACM645;
3. 42CrMo;
4. 9Cr18MoV;
5. SKD61;
6. Tungsten carbide alloy, tungsten carbide nickel-based alloy;
7. Fully hardened powder alloy (full alloy);
8. High temperature alloy.
Double flight conveying elements are the most widely used design in twin screw compounding. They provide the best balance between free volume and torque transmission.
Best suited for:
Feeding sections
Venting zones
Pressure control sections
Robust rectangular spline design providing stable torque transmission with moderate load capacity.
Best suited for:
Medium torque systems
Chemical processing
Replacement applications
Six-sided geometry enabling uniform torque transfer and rapid screw element replacement.
Best suited for:
Powder coating
Frequent material changes
Fast screw configuration changes
SSK conveying elements combine the strong conveying ability of single flight elements with increased free volume.
Best suited for:
Difficult-to-feed materials
Low-density powders and fillers
TME elements use intermeshing toothed discs to split and recombine melt flow, achieving efficient distributive mixing without conveying.
Best suited for:
Melt mixing zones
Fiber-reinforced materials
High homogeneity requirements
Barrel with vent openings enabling efficient removal of volatiles under controlled partial fill and pressure conditions.
Best suited for:
Devolatilization
Moisture removal
Vacuum venting sections
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