Engineering Filaments: PETG, ASA, and Nylon — When and How to Print Them
Why Engineering Filaments?
PLA is great for prototyping, display prints, and parts that stay indoors at room temperature. But the moment you need heat resistance, impact toughness, UV stability, or chemical resistance, you need engineering filaments.
PETG, ASA, and Nylon are the three most accessible engineering materials for FDM printers. Each has distinct strengths and tradeoffs — and each requires specific printer setup and slicer settings to print reliably.
Material Comparison
Here's an honest comparison based on manufacturer data sheets and standardized testing:
| Property | PETG | ASA | Nylon (PA6) |
|---|---|---|---|
| Tensile Strength | ~50 MPa [1] | ~42 MPa [2] | ~70 MPa [3] |
| Impact Resistance | Good | Good | Excellent |
| Heat Resistance (Tg/HDT) | ~80°C [1] | ~100°C [2] | ~75°C (dry) [3] |
| UV Resistance | Moderate | Excellent [2] | Poor |
| Moisture Sensitivity | Moderate | Low | Very High [3] |
| Chemical Resistance | Good | Good | Excellent |
| Warping Tendency | Low–Moderate | Moderate–High | High |
| Print Difficulty | Easy–Moderate | Moderate | Moderate–Hard |
| Enclosure Needed? | Optional | Recommended | Recommended |
| Ventilation Needed? | No | Yes [4] | No |
| Typical Price (1kg) | $18–$28 | $22–$35 | $30–$60 |
Key Takeaways
- PETG is the easiest step up from PLA — it prints on most printers without an enclosure and offers significantly better heat resistance and impact toughness
- ASA is ABS's UV-resistant successor — use it for anything that goes outdoors [2]. It requires similar printing conditions to ABS (enclosure, ventilation)
- Nylon is the strongest of the three but the hardest to print — moisture management is critical, and it needs an enclosure to prevent warping [3]
PETG: The Easy Engineering Filament
PETG (Polyethylene Terephthalate Glycol-modified) is the most popular engineering filament because it's nearly as easy to print as PLA while offering meaningfully better mechanical properties.
Printing Requirements
- Nozzle temperature: 230–250°C [1]
- Bed temperature: 70–80°C [1]
- Enclosure: Not required, but helps with layer adhesion consistency
- Fan cooling: 30–60% (too much cooling weakens layer adhesion) [1]
- Bed surface: PEI sheet works best; glass with glue stick also works. PETG bonds extremely well to PEI — sometimes too well. Use a light coat of glue stick on smooth PEI to act as a release agent.
- Print speed: 40–80mm/s for reliable results
Common PETG Problems and Fixes
- Stringing — PETG strings more than almost any other material. See our stringing guide for detailed fixes, but the short version: lower temp to 225–235°C, enable wipe, use combing mode.
- Bed adhesion too strong — PETG can permanently bond to bare PEI sheets. Always use a release agent (glue stick, hairspray) on smooth PEI.
- Moisture — PETG is moderately hygroscopic. Dry at 65°C for 4–6 hours if you hear popping [1].
- Layer adhesion cracking — Usually caused by too much cooling. Reduce fan speed to 30–50%.
ASA: The Outdoor Engineering Filament
ASA (Acrylonitrile Styrene Acrylate) is essentially ABS with UV resistance. It was developed specifically to address ABS's tendency to yellow and become brittle after sun exposure [2]. If your part goes outdoors, ASA is the default choice.
Printing Requirements
- Nozzle temperature: 240–260°C [2]
- Bed temperature: 90–110°C [2]
- Enclosure: Strongly recommended — ASA warps significantly without one
- Fan cooling: Minimal (0–20%). More cooling = more warping and layer splitting [2]
- Bed surface: PEI, ABS slurry (ABS dissolved in acetone), or Kapton tape
- Print speed: 40–60mm/s recommended
- Ventilation: Required — ASA emits styrene fumes during printing [4]. Print in a well-ventilated area or use a printer with an air filtration system.
Common ASA Problems and Fixes
- Warping — The #1 ASA printing problem. Use an enclosure, high bed temp (100–110°C), and apply ABS slurry or glue stick to the bed. A brim (5–10mm) helps on large parts.
- Layer splitting/cracking — Caused by drafts or insufficient chamber temperature. Ensure your enclosure reaches at least 35–45°C ambient. Eliminate any drafts.
- Rough surface on first layer — ASA is sensitive to first-layer height. Start with 0.2mm first layer height and increase bed temp by 5°C if adhesion is poor.
- Fumes — Not optional to address. ASA releases volatile organic compounds (VOCs) during printing. Use a carbon filter or exhaust fan [4].
Nylon: The Performance King
Nylon (polyamide) offers the best combination of tensile strength, impact resistance, and abrasion resistance of any common FDM filament [3]. It's used in industrial applications like gears, bearings, hinges, and snap-fit enclosures. But it's also the hardest of these three materials to print.
Printing Requirements
- Nozzle temperature: 240–270°C depending on grade [3]
- Bed temperature: 70–90°C [3]
- Enclosure: Required — nylon warps severely without one
- Fan cooling: None for the first 5–10 layers; 0–30% after that
- Bed surface: PEI with glue stick, Garolite (G10 sheet), or specialized nylon adhesives
- Print speed: 30–50mm/s for best results
- Drying: Absolutely mandatory. Nylon absorbs up to 9.5% moisture by weight [3] and must be dried before every print session (70–80°C for 6–12 hours). Print directly from a dry box if possible.
Nylon Grades Explained
Not all nylon is the same:
- PA6 — The most common. High strength (~70 MPa tensile), very hygroscopic, moderate heat resistance [3]
- PA12 — Lower moisture absorption than PA6, easier to print, slightly lower strength
- PA6-CF / PA12-CF — Carbon fiber reinforced. Dramatically increased stiffness and heat resistance, but requires a hardened nozzle [5]
- PA6-GF — Glass fiber reinforced. Better impact resistance than carbon fiber versions. Also needs a hardened nozzle.
Common Nylon Problems and Fixes
- Warping — Use a heated enclosure (60°C+ ambient is ideal), large brim, and Garolite bed surface. Nylon shrinks more than most materials during cooling.
- Moisture — If you hear any popping or see rough surfaces, the filament is wet. Dry before printing, print from a dry box, and store sealed with desiccant [3].
- Stringing — Nylon strings moderately. Use 1–2mm retraction (direct drive) and lower temperature to the minimum that still gives good layer adhesion.
- Bed adhesion — PEI alone often isn't enough. Garolite (G10) sheets provide the best adhesion for nylon. Alternatively, apply a thin layer of PVA glue to PEI.
Enclosure and Ventilation Guide
Engineering filaments often need a controlled printing environment. Here's what you need:
| Material | Enclosure | Target Chamber Temp | Ventilation |
|---|---|---|---|
| PETG | Optional | Ambient–40°C | Not needed |
| ASA | Recommended | 35–50°C | Required [4] |
| Nylon | Required | 45–65°C | Not strictly needed |
Enclosure options:
- Bambu Lab X1C — Built-in enclosure, sufficient for all three materials
- Bambu Lab P1S — Enclosed, works for PETG and ASA; marginal for nylon
- Prusa Enclosure / LACK enclosure — DIY options that work for most materials
- Creality K1 series — Enclosed, good for PETG and ASA
For ventilation, a carbon-activated filter (like the Bambu X1C's built-in filter or a BentoBox-style add-on) is the minimum for ASA. For heavy ASA printing, exhaust the fumes outside with a duct and inline fan [4].
High-Speed Printing with Engineering Filaments
Modern high-speed printers (Bambu Lab, Creality K1, Prusa Core One) can print PLA at 200–500mm/s. Engineering filaments generally cannot match those speeds, but they can go faster than many guides suggest.
Realistic speed ranges for quality prints:
| Material | Safe Speed | Max Speed (with trade-offs) |
|---|---|---|
| PETG | 60–100mm/s | 120–150mm/s |
| ASA | 50–80mm/s | 100–120mm/s |
| Nylon | 40–60mm/s | 80–100mm/s |
Keys to higher speeds:
- Increase nozzle temperature by 5–10°C to maintain flow at higher rates
- Use a high-flow hotend (CHT nozzle or similar) for speeds above 100mm/s
- Reduce cooling — higher speeds generate more heat, so the part cools naturally
- Calibrate pressure advance at the target speed — PA behavior changes with speed [6]
- Accept slightly worse surface quality — engineering parts often prioritize function over finish
Bambu Lab Optimizations
Bambu Lab printers with their high-flow hotends handle engineering filaments well at elevated speeds:
- PETG: Bambu's stock PETG profile runs at 100–120mm/s and works well. Reduce if you see stringing.
- ASA: Use the ABS profile as a starting point. 80–100mm/s with the enclosure closed.
- Nylon: Not officially supported in Bambu Studio profiles, but users report good results with custom profiles at 60–80mm/s with the enclosure at 50°C+.
Filwiz generates printer-specific profiles for Bambu P1S and X1C, including flow rate and speed optimizations tuned for the specific hotend capabilities.
Choosing Your First Engineering Filament
If you're moving beyond PLA for the first time, here's the decision path:
- Start with PETG — it's the most forgiving and prints on almost any printer. Get comfortable with its stringing behavior and bed adhesion quirks before moving to harder materials.
- Move to ASA when you have a project that needs UV resistance — but make sure you have an enclosure and ventilation first.
- Tackle nylon when you specifically need its mechanical properties (extreme toughness, abrasion resistance, self-lubricating for gears) — and be prepared to invest in a dry box setup.
Don't skip PETG and jump straight to nylon. The skills you build dialing in PETG (managing stringing, tuning bed adhesion, understanding cooling trade-offs) directly transfer to printing harder materials.
Sources
- [1]Eastman Chemical, "Eastar Copolyester 6763 (PETG) Technical Data Sheet" — PETG mechanical properties and processing parameters. https://www.eastman.com/pages/producthome.aspx?product=71107096
- [2]BASF/Innofil3D, "ASA Technical Data Sheet" — ASA mechanical properties, UV resistance data, and processing recommendations. https://www.innofil3d.com/product/innofil3d-asa-natural/
- [3]DuPont, "Zytel Nylon Resin Molding Guide" — PA6 mechanical properties, moisture absorption data, and processing parameters. https://www.dupont.com/content/dam/dupont/amer/us/en/performance-polymers/public/documents/en/Zytel-Molding-Guide.pdf
- [4]Azimi et al., "Emissions of Ultrafine Particles and Volatile Organic Compounds from Commercially Available Desktop 3D Printers" (2016), Environmental Science & Technology — study of VOC emissions from ABS and ASA printing. https://doi.org/10.1021/acs.est.5b04983
- [5]E3D, "Nozzle Material Guide" — hardened nozzles for abrasive filaments including carbon fiber and glass fiber composites. https://e3d-online.com/blogs/news/nozzle-materials
- [6]Klipper Documentation, "Pressure Advance" — speed-dependent PA tuning. https://www.klipper3d.org/Pressure_Advance.html