Materials / Compare
Plastic Nylon PA66 vs. Stainless 303
Compare Plastic Nylon PA66 vs. Stainless 303 strength, stiffness, weight and thermal properties.
| Try it on a partA bracket to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 85MPasourcetypical, dry | 275MPasourceOutokumpu typical (product P = hot rolled plate, transverse) |
| Ultimate tensile strength | not sourced | 585MPasourceOutokumpu typical |
| Elongation at break | 30%sourcenominal strain at break, dry | 35%sourceOutokumpu typical, A5 |
| Young's modulus (stiffness) | 3GPasourcetypical, dry | 200GPasourceat RT (Table 12) |
| Density | 1,130kg/m³sourcetypical | 7,900kg/m³sourceat RT |
| Strength to weight | 75.2kN·m/kg2.16x higher | 34.8kN·m/kg |
| Stiffness to weight | 2.65MN·m/kg | 25.3MN·m/kg9.54x higher |
| Poisson's ratio | 0.4sourcebase material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 1.07GPa | 76.9GPa71.8x stiffer in shear |
| Bulk modulus | 5GPa | 167GPa |
| Speed of sound | 1,629m/s | 5,032m/s |
| Thermal | ||
| Thermal conductivity | 0.33W/m·Ksourcetypical | 15W/m·Ksourceat RT |
| Thermal expansion | 98µm/m·Ksourcelongitudinal, 23-55 °C | 16µm/m·Ksourcemean, 20–100 °C |
| 100 mm part over a 50 °C swing | 490µm growth | 80µm growth6.13x less |
| Specific heat | 1,700J/kg·Ksourcetypical | 500J/kg·Ksourceat RT |
| Heats up and cools (diffusivity) | 0.172mm²/s | 3.8mm²/s22.1x faster |
| Thermal shock resistance | 57.2W/m | 902W/m15.8x more resistant |
| Melting point | 260°CsourceDSC | not sourced |
| Max service temperature | 101°CsourceIEC 60216 temperature index, 20000 h | 871°Csourcecontinuous, scaling limit |
| Values for | BASF Ultramid A3K (PA66, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods) | 1.4305 / UNS S30300, Outokumpu typical values (hot rolled, solution annealed) from 'Steel Grades, Properties and Global Standards'; max service from Carpenter CarTech 303 datasheet |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Is Plastic Nylon PA66 stronger than Stainless 303?
Stainless 303 is stronger: its yield strength is 275 MPa against 85 MPa for Plastic Nylon PA66 (3.24x).
Which is lighter, Plastic Nylon PA66 or Stainless 303?
Plastic Nylon PA66 is lighter: 1,130 kg/m³ against 7,900 kg/m³ for Stainless 303.
Which is stiffer, Plastic Nylon PA66 or Stainless 303?
Stainless 303 is stiffer: Young's modulus 200 GPa against 3 GPa for Plastic Nylon PA66, so the same part in Stainless 303 deflects less under the same load.
Which is lighter for the same job, Plastic Nylon PA66 or Stainless 303?
For the same stiffness or strength: Plastic Nylon PA66 is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Stainless 303 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Nylon PA66 | Stainless 303 |
|---|---|---|
| Stiff rod or tie (tension) | 9.54x heavier | lighter |
| Stiff beam (bending) | 17% heavier | lighter |
| Stiff panel or plate | lighter | 1.72x heavier |
| Strong rod or tie | lighter | 2.16x heavier |
| Strong beam | lighter | 3.2x heavier |
| Strong panel or plate | lighter | 3.89x heavier |
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which conducts heat better, Plastic Nylon PA66 or Stainless 303?
Stainless 303 conducts heat better: 15 W/m·K against 0.33 W/m·K for Plastic Nylon PA66.
Which expands less with temperature?
Stainless 303 expands less: 16 µm/m·K against 98 µm/m·K for Plastic Nylon PA66.