In PET sheet extrusion, the roller is not just for shaping—it is a precision heat transfer system.
The internal flow channel design directly determines:
- Temperature uniformity
- Surface quality
- Process stability
Below is a direct comparison between two common designs.
Welded Flow Channel Roller (Low Precision)
Welded internal flow channel roller used in low-cost PET sheet extrusion line.
Key Characteristics:
- Manually welded spiral plates
- Irregular channel geometry
- Uneven flow distribution
Engineering Problems:
- Non-uniform cooling
- Dead zones inside roller
- Temperature fluctuation (±3–5°C)
Result in Production:
- Surface haze
- Gloss inconsistency
- Flow marks
- High reject rate
CNC Machined Flow Channel Roller (High Precision)
CNC machined roller with precision spiral flow channels for PET sheet extrusion.
Key Characteristics:
- Precisely machined spiral channels
- Uniform depth and spacing
- Controlled internal structure
Engineering Advantages:
- Uniform water flow distribution
- No dead zones
- Stable heat transfer
Result in Production:
- Consistent surface quality
- Stable gloss level
- Uniform cooling
- High production yield
Temperature Performance Comparison
| Parameter | Welded Roller | CNC Roller |
|---|---|---|
| Flow uniformity | Poor | Excellent |
| Temperature deviation | ±3–5°C | ≤ ±1°C |
| Dead zones | Yes | No |
| Heat transfer stability | Unstable | Stable |
In PET sheet extrusion, even small temperature differences will directly affect product quality
Non-uniform cooling leads to:
• Internal stress
• Surface defects
• Quality inconsistency
CNC machined rollers ensure:
• Predictable thermal behavior
• Stable production conditions
• Consistent final products
Roller is not a simple component—it is a thermal control system.
Welded structure = Uncontrolled cooling
CNC machining = Controlled and stable performance
For PET sheet extrusion, CNC machined flow channels are a necessity, not an option.
Looking for stable PET sheet extrusion performance?
Choosing the right roller design is the first step.