📏 Uneven Wall Thickness
Causes, Solutions & Prevention in Thermoforming
Significant wall thickness variation. Sidewalls and corners thinner than rim/base. Inherent thermoforming challenge minimizable with plug-assist and zoned heating.
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⚠️Root Causes by Category
⚙️ Process
- Non-uniform heating — hot/cold zones
- Pre-stretch pressure incorrect
- Plug assist timing or temperature wrong
- Sheet sag before forming
🔲 Mold / Tooling
- No plug-assist for deep sections
- Male mold where female would give better distribution
🧪 Sheet / Material
- Sheet thickness not matched to draw depth
📐 Design
- Draw ratio exceeds 3:1 without plug assist
✅Solutions & Corrective Actions
Step 1
- Use zoned heating — more heat to deep-draw areas
Step 2
- Implement plug-assist with syntactic foam at 50–70% depth
Step 3
- Pre-stretch (bubble) sheet before vacuum
Step 4
- Consider female mold for more uniform distribution
🛠️Step-by-Step Troubleshooting
Step 1
Use zoned heating — more heat to deep-draw areas
Step 2
Implement plug-assist with syntactic foam at 50–70% depth
Step 3
Pre-stretch (bubble) sheet before vacuum
Step 4
Consider female mold for more uniform distribution
❓Frequently Asked Questions
What causes uneven wall thickness?
Non-uniform heating — hot/cold zones; Pre-stretch pressure incorrect; Plug assist timing or temperature wrong
How to fix uneven wall thickness?
Use zoned heating — more heat to deep-draw areas
How to prevent uneven wall thickness?
Prevention requires systematic process control: verify sheet temperature, maintain mold vents, ensure proper material drying, and document optimal parameters.
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