Materials / Compare
Plastic POM/Acetal vs. Silicon
Compare Plastic POM/Acetal vs. Silicon strength, stiffness, weight and thermal properties.
| Try it on a partA sample part to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 69MPasourcetypical (single ASTM D638 tensile strength) | not given (tensile used) |
| Ultimate tensile strength | 69MPasourcetypical | 130MPasourcemodulus of rupture (bending fracture stress); brittle, no yield point |
| Compressive strength | 124MPasourcecompressive stress at 10% deformation | not sourced |
| Flexural strength | 99MPasourceflexural yield strength, typical | 130MPasourcemodulus of rupture |
| Elongation at break | 75%sourcetypical | not sourced |
| Young's modulus (stiffness) | 2.8GPasourcetypical | 131GPasourcetypical (single quoted value of an anisotropic crystal) |
| Density | 1,420kg/m³sourcetypical (DuPont product information for Delrin 100 NC010; 'The data listed here fall within the normal range of product properties') | 2,329kg/m³sourcetypical |
| Strength to weight | 48.6kN·m/kg | 55.8kN·m/kg15% higher |
| Stiffness to weight | 1.97MN·m/kg | 56.2MN·m/kg28.5x higher |
| Poisson's ratio | 0.35sourcetypical | 0.221sourcetypical |
| Shear modulus | 1.04GPa | 53.6GPa51.7x stiffer in shear |
| Bulk modulus | 3.11GPa | 78.3GPa |
| Speed of sound | 1,404m/s | 7,500m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical | 163W/m·Ksourcetypical at 313 K (40 °C) |
| Thermal expansion | 122µm/m·Ksourcemean, 29 to 60 °C | 2.62µm/m·Ksourcetypical at 300 K |
| 100 mm part over a 50 °C swing | 610µm growth | 13.1µm growth46.6x less |
| Specific heat | 1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific) | 732J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.192mm²/s | 95.6mm²/s497x faster |
| Thermal shock resistance | 52.5W/m | 48,095W/m916x more resistant |
| Melting point | 175°Csourcecrystalline melting point | 1,412°Csourcetypical |
| Max service temperature | 125°CsourceHDT 1.8 MPa (annealed) | 300°Csourceproducer's maximum application temperature (optical components) |
| Values for | DuPont Delrin 100 acetal homopolymer, Table 2 'Typical Properties of Delrin Acetal Resins' (ASTM methods), Delrin Design Guide Module III hosted on delrin.com | Synthetic single-crystal silicon (cubic, diamond structure), Korth Kristalle (crystal grower) material data; Korth usually supplies Floating Zone (FZ) material, Czochralski (Cz) also offered. Silicon is elastically anisotropic; the producer quotes one modulus and the solver is isotropic. |
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 POM/Acetal stronger than Silicon?
Silicon is stronger: its tensile strength is 130 MPa against yield strength 69 MPa for Plastic POM/Acetal (1.88x).
Which is lighter, Plastic POM/Acetal or Silicon?
Plastic POM/Acetal is lighter: 1,420 kg/m³ against 2,329 kg/m³ for Silicon.
Which is stiffer, Plastic POM/Acetal or Silicon?
Silicon is stiffer: Young's modulus 131 GPa against 2.8 GPa for Plastic POM/Acetal, so the same part in Silicon deflects less under the same load.
Which is lighter for the same job, Plastic POM/Acetal or Silicon?
For the same stiffness or strength: Plastic POM/Acetal is lighter for a strong beam, strong panel or plate; Silicon is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie.
| Part that must be | Plastic POM/Acetal | Silicon |
|---|---|---|
| Stiff rod or tie (tension) | 28.5x heavier | lighter |
| Stiff beam (bending) | 4.17x heavier | lighter |
| Stiff panel or plate | 2.2x heavier | lighter |
| Strong rod or tie | 15% heavier | lighter |
| Strong beam | lighter | 8% heavier |
| Strong panel or plate | lighter | 19% 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 POM/Acetal or Silicon?
Silicon conducts heat better: 163 W/m·K against 0.4 W/m·K for Plastic POM/Acetal.
Which expands less with temperature?
Silicon expands less: 2.62 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.