Material choice decides more about whether a printed part survives service than any slicer setting. It is a systems decision — service temperature, load type, and environment first; printability second. Here is how the common FDM materials actually compare, and how to choose between them without guessing.
The materials, side by side
| Material | Toughness | Max service temp* | Printability | Best for | Watch out |
|---|---|---|---|---|---|
| PLA | Stiff, brittle | ~50 °C | Easiest | Prototypes, jigs, visual models | Creeps under load, low heat, snaps |
| PETG | Tough, ductile | ~70 °C | Easy | Functional brackets, watertight parts | Stringing; weak layers if printed fast/cold |
| ABS | Impact-tough | ~90 °C | Hard (warps) | Enclosures, automotive interior | Warping, fumes; needs an enclosure |
| ASA | Impact-tough, UV-stable | ~95 °C | Hard (warps) | Outdoor / sunlight parts | As ABS; better weathering |
| Nylon (PA) | Very tough, wear-resistant | ~80–120 °C | Hard (hygroscopic) | Gears, hinges, wear surfaces | Absorbs moisture; must be dried |
| PC | Very strong, heat-tough | ~110–130 °C | Very hard | High-heat structural parts | Warps hard; high temps; hygroscopic |
| TPU | Flexible, resilient | ~60–80 °C | Medium | Gaskets, grips, bumpers | Slow prints, stringing |
Three questions that pick the material
- How hot does it get, under load? Compare service temperature to the material's heat-deflection temperature — with margin. A PLA bracket near a motor or in a hot car is a failure waiting to happen.
- What kind of load? Stiff-and-static favors PLA/PETG; impact and repeated flexing favor PETG, ABS, Nylon, or PC. Brittle PLA is the wrong answer for anything that gets dropped, clamped, or snap-fit.
- What's the environment? Sunlight → ASA. Chemicals/moisture → check resistance (Nylon hates humidity, loves oils). Outdoors long-term → not PLA.
A datasheet's headline strength is measured on an injection-molded, dry coupon. Your printed part is weaker across layers and, for Nylon/PC/PETG, weaker still if the filament absorbed moisture. Design with margin.
The printability tax
The tougher, more heat-resistant materials (ABS, ASA, PC, Nylon) all warp — they shrink as they cool and peel off the plate or split between layers. Running them reliably means an enclosure, higher chamber and bed temperatures, adhesion aids, and slower cooling. That tax is real: budget it, or the "stronger" material yields weaker parts than a clean PETG print would have.
For a functional part when you're torn between PLA and PETG, choose PETG. You trade a little print fussiness (stringing) for a large gain in toughness, heat, and layer adhesion — and it rarely warps.
Moisture is a material property too
Nylon, PC, and PETG are hygroscopic — they pull water from the air, which flashes to steam at the nozzle and wrecks layer bonding, surface finish, and strength. Dry the spool before printing (a filament dryer or low oven) and keep it dry mid-print for Nylon and PC. A "bad batch" of Nylon is usually just a wet one.
Choosing a material is one lesson; qualifying it for a real application is a module. The Pro FDM course's materials module covers the big five honestly rated, fiber fills, creep, and how to qualify a material against your load case.
Take the FDM course Next: choosing a processMaterial selection checklist
- Write the service temperature and confirm it's below the material's HDT with margin.
- Classify the load: static-stiff, impact, or repeated flex — and match toughness.
- Check environment: UV, moisture, chemicals, food/skin contact.
- Budget the printability tax (enclosure, drying) before committing to ABS/ASA/PC/Nylon.
- Record the exact SKU — "PETG" is not a specification; brand and grade matter.