💧 Air Bubbles / Blisters
Causes, Solutions & Prevention in Thermoforming
Trapped air or moisture-induced bubbles on/in the part surface. Affects appearance and integrity.
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⚠️Root Causes by Category
⚙️ Process
- Sheet overheated — surface boiling
- Vacuum applied too slowly
🔲 Mold / Tooling
- Insufficient venting in deep pockets
🧪 Sheet / Material
- Moisture content too high — steam bubbles
- Sheet contamination — oils, dust
🔧 Machine
- Heating elements uneven — localized overheating
✅Solutions & Corrective Actions
Step 1
- Pre-dry sheets: PC/PETG 120°C/2–4h; PET 160°C/4h
Step 2
- Add/clean vent holes at trapped-air locations
Step 3
- Reduce heating temperature; avoid degradation
Step 4
- Clean sheet surface before loading
🛠️Step-by-Step Troubleshooting
1
Step 1
Pre-dry sheets: PC/PETG 120°C/2–4h; PET 160°C/4h
2
Step 2
Add/clean vent holes at trapped-air locations
3
Step 3
Reduce heating temperature; avoid degradation
4
Step 4
Clean sheet surface before loading
❓Frequently Asked Questions
What causes air bubbles / blisters?
Sheet overheated — surface boiling; Vacuum applied too slowly; Insufficient venting in deep pockets
How to fix air bubbles / blisters?
Pre-dry sheets: PC/PETG 120°C/2–4h; PET 160°C/4h
How to prevent air bubbles / blisters?
Prevention requires systematic process control: verify sheet temperature, maintain mold vents, ensure proper material drying, and document optimal parameters.
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