DMLS 316L Stainless Steel vs. Plastic POM/Acetal

Compare DMLS 316L Stainless Steel vs. Plastic POM/Acetal strength, stiffness, weight and thermal properties.

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DMLS 316L Stainless Steel3D printed metal (DMLS)

Plastic POM/AcetalBulk polymer (molded or machined)

Mechanical
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Yield strength	530MPasourcetypical, as manufactured, horizontal	69MPasourcetypical (single ASTM D638 tensile strength)
Ultimate tensile strength	640MPasourcetypical, as manufactured, horizontal	69MPasourcetypical
Compressive strength	not sourced	124MPasourcecompressive stress at 10% deformation
Flexural strength	not sourced	99MPasourceflexural yield strength, typical
Elongation at break	40%sourcetypical at break, as manufactured, horizontal	75%sourcetypical
Young's modulus (stiffness)	185GPasourcetypical, as built, horizontal (XY); EOSINT M280-400W / M290-400W, 316L_Surface 1.0, 20 µm (2014 sheet)	2.8GPasourcetypical
Density	7,900kg/m³sourcepart density (ISO 3369, not labelled min or typical), EOS M 290, 40 µm FlexLine	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	67.1kN·m/kg38% higher	48.6kN·m/kg
Stiffness to weight	23.4MN·m/kg11.9x higher	1.97MN·m/kg
Poisson's ratio	0.3sourcebase material: austenitic stainless steels incl. 1.4404 (316L), design value	0.35sourcetypical
Shear modulus	71.2GPa68.6x stiffer in shear	1.04GPa
Bulk modulus	154GPa	3.11GPa
Speed of sound	4,839m/s	1,404m/s
Thermal
Thermal conductivity	16.2W/m·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), at 100 °C	0.4W/m·Ksourcetypical
Thermal expansion	15.7µm/m·Ksourcemean 25-100 °C, ASTM E228	122µm/m·Ksourcemean, 29 to 60 °C
100 mm part over a 50 °C swing	78.6µm growth7.76x less	610µm growth
Specific heat	500J/kg·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), 0-100 °C	1,465J/kg·Ksourceaverage -18 to 100 °C, Delrin acetal resins (not grade-specific)
Heats up and cools (diffusivity)	4.1mm²/s21.3x faster	0.192mm²/s
Thermal shock resistance	2,067W/m39.4x more resistant	52.5W/m
Melting point	not sourced	175°Csourcecrystalline melting point
Max service temperature	not sourced	125°CsourceHDT 1.8 MPa (annealed)
Values for	EOS StainlessSteel 316L (powder 9011-0032), EOS M 290, ParameterSet 316L 20µm Surface M290/400W, as manufactured, horizontal; ISO 6892-1	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.

DMLS 316L Stainless Steel is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is DMLS 316L Stainless Steel stronger than Plastic POM/Acetal?

DMLS 316L Stainless Steel is stronger: its yield strength is 530 MPa against 69 MPa for Plastic POM/Acetal (7.68x).

Which is lighter, DMLS 316L Stainless Steel or Plastic POM/Acetal?

Plastic POM/Acetal is lighter: 1,420 kg/m³ against 7,900 kg/m³ for DMLS 316L Stainless Steel.

Which is stiffer, DMLS 316L Stainless Steel or Plastic POM/Acetal?

DMLS 316L Stainless Steel is stiffer: Young's modulus 185 GPa against 2.8 GPa for Plastic POM/Acetal, so the same part in DMLS 316L Stainless Steel deflects less under the same load.

Which is lighter for the same job, DMLS 316L Stainless Steel or Plastic POM/Acetal?

For the same stiffness or strength: DMLS 316L Stainless Steel is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie; Plastic POM/Acetal is lighter for a stiff panel or plate, strong beam, strong panel or plate.

Part that must be	DMLS 316L Stainless Steel	Plastic POM/Acetal
Stiff rod or tie (tension)	lighter	11.9x heavier
Stiff beam (bending)	lighter	46% heavier
Stiff panel or plate	38% heavier	lighter
Strong rod or tie	lighter	38% heavier
Strong beam	43% heavier	lighter
Strong panel or plate	2.01x 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, DMLS 316L Stainless Steel or Plastic POM/Acetal?

DMLS 316L Stainless Steel conducts heat better: 16.2 W/m·K against 0.4 W/m·K for Plastic POM/Acetal.

Which expands less with temperature?

DMLS 316L Stainless Steel expands less: 15.7 µm/m·K against 122 µm/m·K for Plastic POM/Acetal.

Among 59 materials

Stiffness against density

Strength against density