Every FDM print spends most of its material on the inside. Choosing the right infill pattern and density changes print time, weight, strength and even how the part handles stress. Here is how to decide — informed by how different filaments behave in PLA, PETG, ABS and TPU.
Why Infill Varies So Much
Different filaments carry load differently. A stiff material like PLA relies on the infill skeleton; a tougher one like PETG benefits from walls too; and TPU needs a pattern that flexes without tearing. Understanding the part's purpose is the first step.
Common Pattern Types
| Pattern | Best For | Notes |
|---|---|---|
| Grid | Rigid PLA / PETG parts | Fast, criss-cross lines |
| Gyroid | Balanced strength in all directions | Tougher, smooth stress paths |
| Tri-Hexagon | High-strength engineering parts | Better shear resistance |
| Lines | Simple, low-stress parts | Quickest, least material |
| Tripod / Cross 3D | ABS structural parts | Good against warping stress |
Density Guidelines by Material
- PLA: 15–20% is plenty for decorative and light-duty parts.
- PETG: 20–30% helps with slightly flexible, strong enclosures.
- ABS/ASA: 25–40% for load-bearing and heat-resistant parts.
- TPU: 15–25%; use a gyroid or cross pattern to keep flexibility.
Walls Matter More Than Infill
Counter-intuitively, adding perimeter walls often increases strength more than raising infill. Two or three walls plus a moderate 20% gyroid gives stronger results than a single thin wall at 60% infill — and uses less material.
Pair Strong Settings With Good Filament
No infill choice can fix inconsistent filament. Dimensional accuracy and low moisture make the difference between a brittle shell and a genuinely strong part:
- ANTINSKY PLA+ Filament — great all-round default for infill tests.
- ANTINSKY PETG Filament — stronger and more durable parts.
- ANTINSKY ABS Filament — heat-resistant functional parts.
- ANTINSKY TPU 85A — flexible, shock-absorbing parts.
Rule of thumb: design for strength with walls and correct pattern, then let infill density finish the job. Test one small cube per filament before the full part.