ASA vs PETG for Exterior Parts
UV Durability, Heat Resistance & When to Use Each
The two most popular materials for automotive 3D printing, compared head-to-head. Learn which to choose for your specific application.
Choose PETG If...
Interior trim clips and brackets
Under-dash components
Door panel clips (not sun-exposed)
Glovebox parts
Trunk/cargo area parts
Parts that won't see direct sunlight
Beginners without enclosed printers
Choose ASA If...
Exterior mirror caps and trim
Grille inserts and surrounds
License plate frames
Antenna mounts
Roof rack components
Any part exposed to direct sun
Dashboard parts near windshield
Door handles and exterior trim
Head-to-Head Comparison
| Property | PETG | ASA |
|---|---|---|
| Heat Deflection Temp | ~70-80°C | ~95-100°C |
| UV Resistance | Moderate (will degrade) | Excellent (UV stabilized) |
| Print Difficulty | Easy (no enclosure) | Medium-Hard (enclosure required) |
| Warping Risk | Low | High (needs enclosure) |
| Impact Strength | Medium | High |
| Layer Adhesion | Good | Excellent |
| Surface Finish | Good (slightly glossy) | Excellent (matte, paintable) |
| Chemical Resistance | Good | Better |
| Cost | ~$20-25/kg | ~$25-35/kg |
| Fumes/Ventilation | Low (safe indoors) | High (needs ventilation) |
Recommended Print Settings
PETG Settings
Nozzle Temp:
230-250°C
Bed Temp:
70-85°C
Print Speed:
40-60mm/s
Part Cooling:
50-100%
Enclosure:
Not required
ASA Settings
Nozzle Temp:
240-260°C
Bed Temp:
90-110°C
Print Speed:
40-50mm/s
Part Cooling:
0-30%
Enclosure:
Required (40-60°C chamber)
Real-World Durability Tests
| Test | PETG Result | ASA Result |
|---|---|---|
| Arizona Summer Dashboard Test | Slight warping after 2 weeks at 75°C+ | No change after 3 months |
| UV Exposure (6 months outdoor) | Surface yellowing, slight brittleness | No visible degradation |
| Clip Stress Test (1000 cycles) | Survived with slight deformation | No change |
| Paint Adhesion | Good with proper primer | Excellent, takes paint like OEM |
Frequently Asked Questions
Can I use PETG for exterior parts if I park in shade?
We don't recommend it. Even occasional sun exposure will degrade PETG over time. UV damage is cumulative. For any exterior part, ASA is the right choice.
Is ASA worth the extra difficulty?
For exterior parts, absolutely. The UV stability alone justifies the enclosure requirement. For interior parts not near windows, PETG is often sufficient and much easier to print.
Can I print ASA without an enclosure?
Small parts may work with heavy draft shields and a heated chamber workaround, but expect warping and layer separation on anything larger than a few centimeters. An enclosure is strongly recommended.
Which is stronger for clips that flex?
PETG has more flex before breaking. ASA is stiffer and stronger overall. For clips that need to flex repeatedly, PETG often performs better. For rigidity and heat resistance, ASA wins.
What about blends like ASA-X or PETG-CF?
ASA-X blends are easier to print than pure ASA. CF (carbon fiber) variants add stiffness but require hardened nozzles. Both are good automotive choices for their respective use cases.
Troubleshooting
ASA warps badly even with enclosure
Increase bed temp to 105-110°C. Use ABS slurry (ABS dissolved in acetone) on bed. Add brim. Enable draft shield in slicer. Check for drafts in enclosure.
PETG strings between parts
Increase retraction to 6-8mm. Enable coasting and wipe. Lower temp by 5°C. Dry filament if stored unsealed.
ASA fumes are overwhelming
Print in a well-ventilated area or use an enclosure with HEPA+carbon filter. Consider a fume hood or printing in garage. Never print ASA in living spaces without ventilation.
PETG parts feel too flexible
Increase wall count to 4-5. Use 60%+ infill with gyroid pattern. Consider PETG-CF for added rigidity.
Ready to Print?
Browse exterior parts in the library or learn about print settings next.