Quick Conclusion
For thermoforming trays, thickness selection should follow a design-driven rule, not guesswork.
Recommended ranges:
| Material | Typical Thickness |
|---|---|
| PET sheet | 0.30–0.60 mm |
| PP sheet | 0.45–0.80 mm |
| PS sheet | 0.35–0.70 mm |
The optimal thickness depends on:
- draw ratio
- tray geometry
- stacking load
- transportation requirements
Engineering Principle: Draw Ratio
The draw ratio determines how much the sheet stretches during forming.
Formula:
Draw Ratio = Sheet Area / Tray Surface Area
Typical draw ratios:
| Tray Type | Draw Ratio |
|---|---|
| Shallow tray | 1.5–2.0 |
| Medium depth tray | 2.0–2.5 |
| Deep tray | 2.5–3.5 |
Higher draw ratios require thicker sheets.
Thickness Recommendation by Draw Ratio
| Draw Ratio | Recommended Thickness |
|---|---|
| 1.5–2.0 | 0.30–0.45 mm |
| 2.0–2.5 | 0.40–0.60 mm |
| 2.5–3.0 | 0.55–0.80 mm |
PET vs PP Thickness Comparison
PET trays can often be thinner because PET has higher stiffness.
Example:
| Material | Typical Tray Thickness |
|---|---|
| PET tray | 0.40 mm |
| PP tray | 0.55 mm |
PP requires additional thickness to achieve similar rigidity.
Structural Strength and Stacking Load
For logistics packaging, trays must withstand stacking pressure.
Example calculation:
Stack height: 10 trays
Total weight: 5 kg
Recommended sheet thickness:
0.50–0.70 mm PET
Sustainability Considerations
Many packaging companies are reducing thickness to lower plastic usage.
Typical reduction strategies:
- optimized mold design
- rib reinforcement
- RPET material
This can reduce thickness by 10–15% without losing strength.
Industry Benchmark Thickness
Typical commercial packaging thickness:
| Industry | Thickness |
|---|---|
| Fresh produce | 0.30–0.45 mm |
| Supermarket meat trays | 0.40–0.60 mm |
| Ready-meal trays | 0.60–1.00 mm |
| Electronic packaging | 0.40–0.80 mm |
FAQ
Q1. What thickness is used for PET food trays?
Most PET food trays use 0.35–0.50 mm sheet thickness.
Q2. Why does PP require thicker sheets?
PP has lower stiffness than PET, so additional thickness improves tray rigidity.
Q3. What thickness is used for deep thermoforming trays?
Usually 0.60 mm or thicker.
Q4. Can thin sheets still produce strong trays?
Yes, if the mold design includes structural ribs or reinforced corners.