Which Filament for Which Part? A Practical Table

Most material questions we get are really one question: what does this part have to survive? Temperature, load, sunlight, chemicals and dimensional tolerance decide the material. Everything else, including price, comes after that.

Start with the four questions

• Highest temperature the part sees in service, including a hot car interior or a motor housing
• Type of load: constant pressure, impact, vibration, or none worth mentioning
• Environment: indoors, outdoors with UV, fuel, cleaning agents, humidity
• Tolerance: does it have to fit another part, or is it a visual model

PLA: models, jigs, anything indoors and cool

PLA is dimensionally the most predictable material in FDM and the cheapest to print. It stays stiff at room temperature and starts to soften noticeably around 55 to 60 °C. Use it for form and fit studies, assembly checks, display models and workshop jigs that never see heat. Do not use it in a car, near a motor, or outdoors.

PETG: the default for real parts

PETG is the material we recommend most often for functional parts that stay under roughly 70 °C. It is tougher than PLA, does not shatter, tolerates humidity and most cleaning agents, and prints reliably in larger sizes. Typical parts: enclosures, brackets, guards, fluid handling housings, spare parts for machines.

ABS and ASA: heat, outdoors, automotive

Both handle roughly 90 to 100 °C and can be vapour smoothed or machined cleanly. ASA is the better choice whenever the part sits outdoors, because it keeps its colour and impact strength under UV where ABS turns yellow and brittle. ABS remains sensible for interior parts where cost matters more than weathering.

PC and PC FR: high temperature and flame retardancy

Polycarbonate holds structural stiffness well above 110 °C and is very impact resistant, which makes it the right answer for lighting housings, transparent guards and load bearing brackets close to a heat source. PC FR with a UL94 V-0 rating is what you use when an electrical enclosure has to pass a flammability requirement.

PA12 and PA12-CF: wear, snap fits, chemicals

Nylon is the material for parts that move: gears, bushings, cable guides, living hinges and snap fits. It resists fuels and oils and survives repeated deflection that would crack PETG. Unfilled PA12 absorbs moisture and moves dimensionally, so for tight tolerances and stiffness we use the carbon filled PA12-CF instead.

Carbon fiber variants: stiffness, not strength

PETG-CF, PA12-CF and PLA-CF gain stiffness, dimensional stability and a matt surface. What they lose is impact toughness and layer ductility. Choose a CF grade when a part must not deflect under load, not when it has to absorb a knock.

The short version

• Model, jig, indoors and cool: PLA
• Functional part under 70 °C: PETG
• Outdoors with UV: ASA
• Interior part with heat, cost sensitive: ABS
• Above 100 °C or transparent and tough: PC, or PC FR for UL94 V-0
• Moving, wearing, chemical contact: PA12, PA12-CF for tolerances
• Must not deflect: any CF grade

If you are unsure, send the part and its operating conditions. We will name the material and say why, including when a cheaper one is enough.