Detailed Introduction to the Structure of Twin-Screw PET Sheet Extrusion Line

Structure Composition of Twin-Screw PET Sheet Extruder

1. Feeding System

• Hopper with magnetic grid: Removes metal impurities to protect screws and barrel.
• Volumetric or gravimetric feeder: Ensures stable, uniform feeding, preventing fluctuation of output and melt quality.

2. Barrel & Twin Screw Assembly (Core Component)

• Co-rotating parallel twin screws: Designed with segmented screw elements (transporting, shearing, mixing, kneading blocks) for strong plasticization, uniform dispersion, and self-cleaning ability.
• Multi-zone heated barrel: Equipped with electric heating and air/water cooling system, precisely controlling temperature in multiple zones to avoid overheating or insufficient melting.
• Barrel liner: Wear-resistant and corrosion-resistant, extending service life especially for recycled PET (rPET).

3. Venting / Devolatilization System

• Multi-stage vacuum vents: Effectively extracts moisture, volatile organic compounds, oligomers and low-molecular substances.
• Prevents hydrolytic degradation, bubbles, yellowing and pinholes in PET sheets.

4. Drive System

• High-torque gearbox: Provides stable power output under high load.
• Inverter motor: Adjustable speed for precise control of screw speed, output and melting degree.

5. Melt Filtering System

• Screen changer (hydraulic double-plate or continuous): Filters impurities in melt without stopping production, ensuring sheet surface cleanliness.

6. Sheet Die Head

• Coat-hanger die with flexible lip: Ensures uniform melt distribution across the entire width.
• Adjustable die lip for precise control of sheet thickness.

7. Three-Roll Calender & Cooling System

• Three precision-chromed rolls: Vertical or horizontal structure.
• Functions: leveling, thickness setting, high-efficiency cooling, polishing, improving transparency and smoothness of PET sheet.

8. Haul-off & Winding System

• Constant-tension haul-off unit: Ensures stable sheet conveying.
• Center winding or surface winding machine: Automatic tension control, achieving neat, flat rolls without wrinkling or deformation.

9. Electrical Control System

• PLC + touch screen: Centralized control of temperature, screw speed, vacuum, roll speed, tension and total parameters.
• Human-machine interface, easy operation, fault alarm and data monitoring.