Materials / Compare
Glass vs. FDM Polycarbonate
Compare Glass vs. FDM Polycarbonate 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 | not given (tensile used) | 53.3MPasourcetypical |
| Ultimate tensile strength | 41MPasourcetypical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probability | 53.3MPasourcetypical, peak stress (= stress at yield) |
| Flexural strength | 41MPasourcemean MOR (same value as tensile) | 89.4MPasourcetypical |
| Elongation at break | not sourced | 9.2%sourcetypical |
| Young's modulus (stiffness) | 72GPasourcetypical30.1x stiffer | 2.39GPasourcetypical |
| Density | 2,500kg/m³sourcetypical | 1,180–1,200kg/m³sourcerange |
| Strength to weight | 16.4kN·m/kg | 44.8kN·m/kg2.73x higher |
| Stiffness to weight | 28.8MN·m/kg14.3x higher | 2.01MN·m/kg |
| Poisson's ratio | 0.22sourcetypical | 0.38sourcebase material: polycarbonate family typical (Covestro Part and Mold Design guide, Table 3-1) |
| Shear modulus | 29.5GPa34x stiffer in shear | 0.867GPa |
| Bulk modulus | 42.9GPa | 3.33GPa |
| Speed of sound | 5,367m/s | 1,418m/s |
| Thermal | ||
| Thermal conductivity | 0.937W/m·Ksourcetypical at 75 F | 0.2W/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, through-plane, 23 °C |
| Thermal expansion | 8.3µm/m·Ksourcetypical, 75-575 F | 65µm/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, 23-55 °C, parallel |
| 100 mm part over a 50 °C swing | 41.5µm growth7.83x less | 325µm growth |
| Specific heat | 880J/kg·Ksourcetypical at 75 F | not sourced |
| Heats up and cools (diffusivity) | 0.426mm²/s | not sourced |
| Thermal shock resistance | 50.1W/m18% more resistant | 42.5W/m |
| Glass transition | not sourced | 108°Csourcetypical |
| Max service temperature | 511°Csourcestrain point (ASTM C336) - stress-relaxation onset, not a rated service limit | 105°CsourceHDT 0.455 MPa (printed specimens) |
| Values for | Annealed soda-lime-silica float glass, Pilkington North America Technical Bulletin ATS-129 (04/2025) | Ultimaker PC, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS (file v5.00), April 20, 2022. |
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.
FDM Polycarbonate is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Glass stronger than FDM Polycarbonate?
FDM Polycarbonate is stronger: its yield strength is 53.3 MPa against tensile strength 41 MPa for Glass (30%).
Which is lighter, Glass or FDM Polycarbonate?
FDM Polycarbonate is lighter: 1,190 kg/m³ against 2,500 kg/m³ for Glass.
Which is stiffer, Glass or FDM Polycarbonate?
Glass is stiffer: Young's modulus 72 GPa against 2.39 GPa for FDM Polycarbonate, so the same part in Glass deflects less under the same load.
Which is lighter for the same job, Glass or FDM Polycarbonate?
For the same stiffness or strength: Glass is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; FDM Polycarbonate is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Glass | FDM Polycarbonate |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 14.3x heavier |
| Stiff beam (bending) | lighter | 2.61x heavier |
| Stiff panel or plate | lighter | 48% heavier |
| Strong rod or tie | 2.73x heavier | lighter |
| Strong beam | 2.5x heavier | lighter |
| Strong panel or plate | 2.4x 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, Glass or FDM Polycarbonate?
Glass conducts heat better: 0.937 W/m·K against 0.2 W/m·K for FDM Polycarbonate.
Which expands less with temperature?
Glass expands less: 8.3 µm/m·K against 65 µm/m·K for FDM Polycarbonate.