Materials / Compare
Iron vs. Plastic POM/Acetal
Compare Iron vs. Plastic POM/Acetal 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 | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal | 69MPasourcetypical (single ASTM D638 tensile strength) |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 69MPasourcetypical |
| Compressive strength | not sourced | 124MPasourcecompressive stress at 10% deformation |
| Flexural strength | not sourced | 99MPasourceflexural yield strength, typical |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 75%sourcetypical |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 2.8GPasourcetypical |
| Density | 7,860kg/m³sourcetypical | 1,420kg/m³sourcetypical (DuPont product information for Delrin 100 NC010; 'The data listed here fall within the normal range of product properties') |
| Strength to weight | 23.7kN·m/kg | 48.6kN·m/kg2.05x higher |
| Stiffness to weight | 26.3MN·m/kg13.4x higher | 1.97MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.35sourcetypical |
| Shear modulus | 80.7GPa77.8x stiffer in shear | 1.04GPa |
| Bulk modulus | 158GPa | 3.11GPa |
| Speed of sound | 5,132m/s | 1,404m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 0.4W/m·Ksourcetypical |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 122µm/m·Ksourcemean, 29 to 60 °C |
| 100 mm part over a 50 °C swing | 68.5µm growth8.91x less | 610µm growth |
| Specific heat | 450J/kg·Ksourcetypical | 1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific) |
| Heats up and cools (diffusivity) | 20.7mm²/s108x faster | 0.192mm²/s |
| Thermal shock resistance | 3,447W/m65.6x more resistant | 52.5W/m |
| Melting point | 1,532°Csourcetypical | 175°Csourcecrystalline melting point |
| Max service temperature | not sourced | 125°CsourceHDT 1.8 MPa (annealed) |
| Values for | Cleveland-Cliffs / AK Steel ARMCO Pure Iron Product Data Bulletin (07/2022): Table 1 typical physical properties, Table 2 typical mechanical properties after SRA/recrystallization anneal. | DuPont Delrin 100 acetal homopolymer, Table 2 'Typical Properties of Delrin Acetal Resins' (ASTM methods), Delrin Design Guide Module III hosted on delrin.com |
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 Iron stronger than Plastic POM/Acetal?
Iron is stronger: its yield strength is 186 MPa against 69 MPa for Plastic POM/Acetal (2.7x).
Which is lighter, Iron or Plastic POM/Acetal?
Plastic POM/Acetal is lighter: 1,420 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Plastic POM/Acetal?
Iron is stiffer: Young's modulus 207 GPa against 2.8 GPa for Plastic POM/Acetal, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Plastic POM/Acetal?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending); Plastic POM/Acetal is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Plastic POM/Acetal |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 13.4x heavier |
| Stiff beam (bending) | lighter | 1.55x heavier |
| Stiff panel or plate | 32% heavier | lighter |
| Strong rod or tie | 2.05x heavier | lighter |
| Strong beam | 2.86x heavier | lighter |
| Strong panel or plate | 3.37x 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, Iron or Plastic POM/Acetal?
Iron conducts heat better: 73.2 W/m·K against 0.4 W/m·K for Plastic POM/Acetal.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.