Which 3D Printed Parts Survive Outdoors and Under the Hood
· 2 min read
The parts people most need replaced are the ones that lived outside or in a hot car, because that is what broke them in the first place. A printed replacement in the wrong material will fail the same way, sometimes in one summer. Here is how we choose for sun, heat, and weather.
The two enemies
UV breaks polymer chains at the surface. The part chalks, fades, and turns brittle, then cracks at the first stress. Heat softens the whole part. A closed car in Georgia sun reaches well past 60 C on the dash, and plastics with a heat deflection temperature below that sag or warp. Many parts face both at once.
Material by exposure
| Where the part lives | Material | Why |
|---|---|---|
| Outdoors in sun and rain, boat and RV exteriors, patio furniture | ASA | UV stabilized by formulation. Manufacturers (Bambu Lab, Prusament, Polymaker) describe ASA as UV and weather resistant, and it holds color where ABS chalks. Our default for anything that sees sky. |
| Hot car interiors, dash and console parts | ASA, or polycarbonate near vents and the windshield | Heat deflection in the 93 to 100 C range for ASA and 110 C plus for PC covers cabin temperatures with margin. |
| Engine bay surfaces away from the exhaust | Polycarbonate or carbon fiber nylon | Highest heat tolerance of the common FDM materials. Still not for anything touching the exhaust or in the combustion path. |
| Outdoor structural brackets and mounts | Carbon fiber nylon, painted or coated for UV | Stiffness and heat resistance, but nylon is not inherently UV stable, so it gets a UV resistant paint or sits in shade. |
| Gaskets, bumpers, and seals outdoors | TPU | Flexible and weather tolerant. Dark colors last longer in sun. |
| Anything outdoors or in a vehicle | Not PLA | PLA softens around 55 C and degrades in sun. We do not use it for these jobs. |
What we do not claim
No filament maker publishes hours to failure in sunlight, so we do not call any material UV proof. ASA is UV stabilized and outlasts the ABS most original parts were made from. That is the defensible statement, and it has held up on the boat, RV, and vehicle parts we make.
Design helps as much as material
Thicker walls survive UV longer because the degraded surface layer is a smaller share of the part. Rounded corners spread stress that sun embrittlement would otherwise find. Dark pigments protect the polymer underneath. And a coat of UV resistant paint on a nylon or polycarbonate part adds years. We build these in when we rebuild the part.
Send us the failed part
The way the original failed tells us what killed it. Chalky and cracked means UV. Warped means heat. Snapped at a corner means stress plus embrittlement. Mail it in and we pick the material and the design changes that address the actual cause.