PET Sheet Extrusion Machine and Production Process
With excellent transparency, toughness, environmental friendliness and recyclability, PET sheets are widely used in food packaging, thermoforming, electronics packaging and industrial plastic industries.
1. Core Configuration of PET Sheet Extrusion Line
A complete PET sheet extrusion production line is an automated integrated system. Each unit coordinates closely to ensure uniform sheet thickness, smooth surface and stable forming effect. The core configurations are as follows:
|
Equipment Unit |
Core Function |
Process Feature |
|---|---|---|
|
Dehumidifying Dryer & Crystallizer |
Remove moisture and crystallize PET raw materials to avoid bubble and yellowing defects |
PET is highly hygroscopic; professional drying and crystallization are essential for high-quality sheets |
|
Single-Screw Extruder |
Melt and plasticize PET pellets/flakes evenly with stable material output |
Adopts professional PET screw design, precise temperature control (240–285°C) |
|
Melt Pump & Screen Changer |
Filter impurities and stabilize melt pressure |
Ensure consistent sheet density and no surface particles |
|
T-type Extrusion Die |
Spread molten PET into flat sheet with adjustable thickness |
Coat-hanger die design for uniform full-width material distribution |
|
Three-Roll Calender |
Cool, shape and calibrate sheet thickness |
Precise roller gap control, determine sheet flatness and gloss |
|
Haul-off & Cutting/Winding Unit |
Traction, fixed-length cutting or rolling finished sheets |
Stepless speed synchronization to avoid sheet stretching and deformation |
2. 6-Step PET Sheet Production Process (Standard Flow)
The entire PET sheet extrusion process is continuous and standardized. Every step directly affects the final sheet quality:
- Raw Material Preparation & Crystallization Put virgin PET pellets or recycled rPET flakes into the crystallization system to eliminate material adhesion, improve molecular structure stability, and lay a foundation for uniform melting.
- Dehumidification & Drying Strictly remove internal moisture of PET materials. Un-dampened materials will cause sheet bubbles, silver lines and reduced transparency.
- High-Temperature Melting & Plasticizing Materials enter the extruder, and are heated, sheared and melted evenly through multi-stage temperature zones to form uniform PET melt.
- Filtration & Pressure Stabilization The melt pump stabilizes extrusion pressure, and the screen changer filters impurities to ensure pure and smooth melt.
- Die Extrusion & Roller Calibration The flat die extrudes the sheet evenly. The three-roll calender cools and calibrates the hot sheet to fix thickness, flatness and surface gloss.
- Traction, Cutting & Finishing Finished sheets are pulled at a constant speed, then cut to fixed length or wound into rolls for storage and transportation.
3. Key Production Quality Control Tips
Temperature Control: Strictly follow PET temperature gradient standards to avoid material decomposition, yellowing or insufficient melting.
Moisture Control: Drying time and dehumidification degree must meet standards, which is the core of avoiding sheet surface defects.
Even small deviations in temperature and moisture will directly affect sheet clarity and yield. Always monitor these two parameters during continuous PET sheet production to keep consistent product quality.
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