PETG-GF: density, print temperature and when to choose it
PETG-GF is PETG reinforced with short glass fibers (usually 10–15% by weight). The fibers increase stiffness and reduce the tendency to deform while cooling — PETG on its own isn't as warp-prone as ABS, but adding glass fiber makes the geometry even more stable, especially on large flat parts.
Key properties
| Parameter | Value |
|---|---|
| Density | ≈1.40 g/cm³ (higher than plain PETG — glass fiber is denser than the polymer) |
| Nozzle temperature | 240–260°C |
| Bed temperature | 70–85°C |
| Part cooling | 20–40% (same as plain PETG — strong cooling hurts interlayer adhesion) |
| Shrinkage | minimal, lower than unmodified PETG |
| Enclosure required | recommended for large parts |
When to use it
- Large rigid functional parts where geometric stability matters more than with plain PETG.
- Industrial brackets, guides, and housings operating under moderate heat that need PETG's chemical resistance.
- Replacing PETG-CF where conductivity isn't needed and a lighter/semi-transparent part color is preferred.
When to pick something else
- You need maximum stiffness at minimum weight — PETG-CF is usually stiffer at comparable or lower density.
- Printing without a hardened nozzle — glass fiber is abrasive; on brass you're better off staying with plain PETG.
- You need heat resistance beyond PETG's typical range (around 70–80°C) — consider PETG-HT or PC.
Pros and cons
Pros: high stiffness and minimal warping even on large parts, retains base PETG's chemical and moisture resistance, doesn't shield radio signals unlike carbon-fiber alternatives.
Cons: the glass fiber is abrasive and requires a hardened nozzle, the composite is noticeably heavier than plain PETG, costs more than base PETG.
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As with any glass- or carbon-fiber composite, the main hidden cost driver is nozzle wear: without hardened steel, a brass nozzle wears out within one to two spools, hurting print accuracy. Budget hardened-nozzle depreciation as its own line item, plus the higher material consumption per gram from increased density, when pricing a part.