Materials / Compare
Plastic PMMA vs. Stainless 316
Compare Plastic PMMA vs. Stainless 316 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 | not given (tensile used) | 265MPasourcetypical (representative), annealed 1.0 mm sheet |
| Ultimate tensile strength | 80MPasourcetypical, 23 °C | 583MPasourcetypical (representative), annealed 1.0 mm sheet |
| Compressive strength | 110MPasourcecompressive yield stress, typical | not sourced |
| Flexural strength | 115MPasourcetypical | not sourced |
| Elongation at break | 5.5%sourcetypical | 61%sourcetypical (representative), annealed, in 2 in. (51 mm) |
| Young's modulus (stiffness) | 3.3GPasourcetypical, short-term | 200GPasourcetypical, in tension |
| Density | 1,190kg/m³sourcetypical6.75x lighter | 8,027kg/m³sourcetypical |
| Strength to weight | 67.2kN·m/kg2.04x higher | 33kN·m/kg |
| Stiffness to weight | 2.77MN·m/kg | 24.9MN·m/kg8.98x higher |
| Poisson's ratio | 0.37sourcetypical | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 1.2GPa | 76.9GPa63.9x stiffer in shear |
| Bulk modulus | 4.23GPa | 167GPa |
| Speed of sound | 1,665m/s | 4,992m/s |
| Thermal | ||
| Thermal conductivity | 0.19W/m·Ksourcetypical | 14.6W/m·Ksource20–100 °C |
| Thermal expansion | 70µm/m·Ksource0-50 °C | 16.5µm/m·Ksourcemean, 20–100 °C |
| 100 mm part over a 50 °C swing | 350µm growth | 82.5µm growth4.24x less |
| Specific heat | 1,470J/kg·Ksourcetypical | 450J/kg·Ksourceat 20 °C |
| Heats up and cools (diffusivity) | 0.109mm²/s | 4.04mm²/s37.2x faster |
| Thermal shock resistance | 41.5W/m | 821W/m19.8x more resistant |
| Melting point | not sourced | 1,390–1,440°Csourcemelting range |
| Max service temperature | 80°Csourcemax. permanent service temperature | 871–899°Csourceoxidation (scaling) limit in air |
| Values for | Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1) | ATI 316 (UNS S31600), annealed 1.0 mm sheet, ATI technical data sheet (2012); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 PMMA stronger than Stainless 316?
Stainless 316 is stronger: its yield strength is 265 MPa against tensile strength 80 MPa for Plastic PMMA (3.31x).
Which is lighter, Plastic PMMA or Stainless 316?
Plastic PMMA is lighter: 1,190 kg/m³ against 8,027 kg/m³ for Stainless 316.
Which is stiffer, Plastic PMMA or Stainless 316?
Stainless 316 is stiffer: Young's modulus 200 GPa against 3.3 GPa for Plastic PMMA, so the same part in Stainless 316 deflects less under the same load.
Which is lighter for the same job, Plastic PMMA or Stainless 316?
For the same stiffness or strength: Plastic PMMA is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Stainless 316 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic PMMA | Stainless 316 |
|---|---|---|
| Stiff rod or tie (tension) | 8.98x heavier | lighter |
| Stiff beam (bending) | 15% heavier | lighter |
| Stiff panel or plate | lighter | 1.72x heavier |
| Strong rod or tie | lighter | 2.04x heavier |
| Strong beam | lighter | 3.04x heavier |
| Strong panel or plate | lighter | 3.71x 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 PMMA or Stainless 316?
Stainless 316 conducts heat better: 14.6 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Stainless 316 expands less: 16.5 µm/m·K against 70 µm/m·K for Plastic PMMA.