Materials / Compare
Aluminum vs. Plastic PEEK
Compare Aluminum vs. Plastic PEEK 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 | 98MPasourcetypical, tensile yield |
| Ultimate tensile strength | 310MPasourcetypical | not sourced |
| Compressive strength | not sourced | 125MPasourcetypical, 23 C |
| Flexural strength | not sourced | 165MPasourcetypical, flexural stress at yield, 23 C |
| Elongation at break | 17%sourcetypical, in 4D, 0.500 in dia specimen | 25%sourcetypical, at break |
| Young's modulus (stiffness) | 68.3GPasourcetypical | 4GPasourcetypical (nominal) |
| Density | 2,700kg/m³sourcenominal | 1,300kg/m³sourcetypical (crystalline) |
| Strength to weight | 102kN·m/kg36% higher | 75.4kN·m/kg |
| Stiffness to weight | 25.3MN·m/kg8.22x higher | 3.08MN·m/kg |
| Poisson's ratio | 0.33sourcetypical (handbook physical constant) | 0.38sourcetypical |
| Shear modulus | 25.7GPa17.7x stiffer in shear | 1.45GPa |
| Bulk modulus | 67GPa | 5.56GPa |
| Speed of sound | 5,030m/s | 1,754m/s |
| Thermal | ||
| Thermal conductivity | 167W/m·Ksourcetypical, 20 °C | 0.29W/m·Ksourcetypical, average, 23 C |
| Thermal expansion | 23.6µm/m·Ksourcetypical, mean 20-100 °C | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) |
| 100 mm part over a 50 °C swing | 118µm growth2.33x less | 275µm growth |
| Specific heat | 896J/kg·Ksourcetypical, at 100 °C | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) |
| Heats up and cools (diffusivity) | 69mm²/s681x faster | 0.101mm²/s |
| Thermal shock resistance | 19,159W/m239x more resistant | 80.1W/m |
| Melting point | 582–652°Csourcesolidus-liquidus | 343°Csourcetypical, DSC |
| Glass transition | not sourced | 143°Csourceonset (midpoint 150 C) |
| Max service temperature | not sourced | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) |
| Values for | 6061-T6/T651, Kaiser Aluminum typical properties (sheet, coil & plate datasheet); Poisson from MIL-HDBK-5J | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) |
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 PEEK?
Aluminum is stronger: its yield strength is 276 MPa against 98 MPa for Plastic PEEK (2.82x).
Which is lighter, Aluminum or Plastic PEEK?
Plastic PEEK is lighter: 1,300 kg/m³ against 2,700 kg/m³ for Aluminum.
Which is stiffer, Aluminum or Plastic PEEK?
Aluminum is stiffer: Young's modulus 68.3 GPa against 4 GPa for Plastic PEEK, so the same part in Aluminum deflects less under the same load.
Which is lighter for the same job, Aluminum or Plastic PEEK?
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; Plastic PEEK is lighter for a strong beam, strong panel or plate.
| Part that must be | Aluminum | Plastic PEEK |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 8.22x heavier |
| Stiff beam (bending) | lighter | 1.99x heavier |
| Stiff panel or plate | lighter | 24% heavier |
| Strong rod or tie | lighter | 36% heavier |
| Strong beam | 4% heavier | lighter |
| Strong panel or plate | 24% 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 PEEK?
Aluminum conducts heat better: 167 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
Aluminum expands less: 23.6 µm/m·K against 55 µm/m·K for Plastic PEEK.