FDM Polycarbonate vs. Magnesium AZ91D

Compare FDM Polycarbonate vs. Magnesium AZ91D strength, stiffness, weight and thermal properties.

Change either side

Mechanical
Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	53.3MPasourcetypical	150MPasourcetypical, 0.2% tensile yield, ambient temperature
Ultimate tensile strength	53.3MPasourcetypical, peak stress (= stress at yield)	230MPasourcetypical, ambient temperature
Flexural strength	89.4MPasourcetypical	not sourced
Elongation at break	9.2%sourcetypical	3%sourcetypical, ambient temperature
Young's modulus (stiffness)	2.39GPasourcetypical	45GPasourcetypical18.8x stiffer
Density	1,180–1,200kg/m³sourcerange	1,810kg/m³sourcetypical
Strength to weight	44.8kN·m/kg	82.9kN·m/kg1.85x higher
Stiffness to weight	2.01MN·m/kg	24.9MN·m/kg12.4x higher
Poisson's ratio	0.38sourcebase material: polycarbonate family typical (Covestro Part and Mold Design guide, Table 3-1)	0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant)
Shear modulus	0.867GPa	16.7GPa19.2x stiffer in shear
Bulk modulus	3.33GPa	50GPa
Speed of sound	1,418m/s	4,986m/s
Thermal
Thermal conductivity	0.2W/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, through-plane, 23 °C	72W/m·Ksourcetypical
Thermal expansion	65µm/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, 23-55 °C, parallel	25µm/m·Ksourcetypical, temperature range not stated
100 mm part over a 50 °C swing	325µm growth	125µm growth2.6x less
Specific heat	not sourced	1,050J/kg·Ksourcetypical
Heats up and cools (diffusivity)	not sourced	37.9mm²/s
Thermal shock resistance	42.5W/m	6,240W/m147x more resistant
Melting point	not sourced	470–595°Csourcemelting range
Glass transition	108°Csourcetypical	not sourced
Max service temperature	105°CsourceHDT 0.455 MPa (printed specimens)	not sourced
Values for	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.	ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.

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 FDM Polycarbonate stronger than Magnesium AZ91D?

Magnesium AZ91D is stronger: its yield strength is 150 MPa against 53.3 MPa for FDM Polycarbonate (2.81x).

Which is lighter, FDM Polycarbonate or Magnesium AZ91D?

FDM Polycarbonate is lighter: 1,190 kg/m³ against 1,810 kg/m³ for Magnesium AZ91D.

Which is stiffer, FDM Polycarbonate or Magnesium AZ91D?

Magnesium AZ91D is stiffer: Young's modulus 45 GPa against 2.39 GPa for FDM Polycarbonate, so the same part in Magnesium AZ91D deflects less under the same load.

Which is lighter for the same job, FDM Polycarbonate or Magnesium AZ91D?

For the same stiffness or strength: Magnesium AZ91D is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	FDM Polycarbonate	Magnesium AZ91D
Stiff rod or tie (tension)	12.4x heavier	lighter
Stiff beam (bending)	2.85x heavier	lighter
Stiff panel or plate	1.75x heavier	lighter
Strong rod or tie	1.85x heavier	lighter
Strong beam	31% heavier	lighter
Strong panel or plate	10% 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, FDM Polycarbonate or Magnesium AZ91D?

Magnesium AZ91D conducts heat better: 72 W/m·K against 0.2 W/m·K for FDM Polycarbonate.

Which expands less with temperature?

Magnesium AZ91D expands less: 25 µm/m·K against 65 µm/m·K for FDM Polycarbonate.

Among 72 materials

Stiffness against density

Strength against density