Materials / Compare
Aluminum vs. Plastic Polycarbonate
Compare Aluminum vs. Plastic Polycarbonate 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 | 276MPasourcetypical, 0.2% offset, .500 in dia specimen | 65MPasourcetypical, tensile yield |
| Ultimate tensile strength | 310MPasourcetypical | 65MPasourcetypical, stress at break |
| Flexural strength | not sourced | 97MPasourcetypical, flexural strength |
| Elongation at break | 17%sourcetypical, in 4D, 0.500 in dia specimen | 125%sourcetypical, strain at break |
| Young's modulus (stiffness) | 68.3GPasourcetypical28.5x stiffer | 2.4GPasourcetypical |
| Density | 2,700kg/m³sourcenominal | 1,200kg/m³sourcetypical |
| Strength to weight | 102kN·m/kg1.89x higher | 54.2kN·m/kg |
| Stiffness to weight | 25.3MN·m/kg12.6x higher | 2MN·m/kg |
| Poisson's ratio | 0.33sourcetypical (handbook physical constant) | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) |
| Shear modulus | 25.7GPa29.5x stiffer in shear | 0.87GPa |
| Bulk modulus | 67GPa | 3.33GPa |
| Speed of sound | 5,030m/s | 1,414m/s |
| Thermal | ||
| Thermal conductivity | 167W/m·Ksourcetypical, 20 °C | 0.2W/m·Ksourcetypical, through-plane, 23 C |
| Thermal expansion | 23.6µm/m·Ksourcetypical, mean 20-100 °C | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal |
| 100 mm part over a 50 °C swing | 118µm growth2.75x less | 325µm growth |
| Specific heat | 896J/kg·Ksourcetypical, at 100 °C | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 |
| Heats up and cools (diffusivity) | 69mm²/s485x faster | 0.142mm²/s |
| Thermal shock resistance | 19,159W/m371x more resistant | 51.7W/m |
| Melting point | 582–652°Csourcesolidus-liquidus | not sourced |
| Glass transition | not sourced | 144°Csourcetypical, DSC 10 C/min |
| Max service temperature | not sourced | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm |
| Values for | 6061-T6/T651, Kaiser Aluminum typical properties (sheet, coil & plate datasheet); Poisson from MIL-HDBK-5J | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values |
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 Aluminum stronger than Plastic Polycarbonate?
Aluminum is stronger: its yield strength is 276 MPa against 65 MPa for Plastic Polycarbonate (4.25x).
Which is lighter, Aluminum or Plastic Polycarbonate?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 2,700 kg/m³ for Aluminum.
Which is stiffer, Aluminum or Plastic Polycarbonate?
Aluminum is stiffer: Young's modulus 68.3 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Aluminum deflects less under the same load.
Which is lighter for the same job, Aluminum or Plastic Polycarbonate?
For the same stiffness or strength: Aluminum is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam; Plastic Polycarbonate is lighter for a strong panel or plate.
| Part that must be | Aluminum | Plastic Polycarbonate |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 12.6x heavier |
| Stiff beam (bending) | lighter | 2.37x heavier |
| Stiff panel or plate | lighter | 36% heavier |
| Strong rod or tie | lighter | 1.89x heavier |
| Strong beam | lighter | 17% heavier |
| Strong panel or plate | 9% heavier | lighter |
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, Aluminum or Plastic Polycarbonate?
Aluminum conducts heat better: 167 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Aluminum expands less: 23.6 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.