Grey vs PETG
Polymer · grade comparison
Grey and PETG are both polymer grades, both multipurpose plastic. Grey is the stronger of the two: tensile strength 55 MPa (7.98 ksi) against 50 MPa (7.25 ksi) for PETG, about 10% more. In exchange, PETG is the more ductile: elongation 120% versus 8% for Grey. Grey is lighter (1.15 g/cm³ vs 1.27 g/cm³ for PETG) and Grey is stiffer (2.5 GPa vs 2.1 GPa). On the shop floor, PETG machines more easily (good vs fair) and PETG welds better (very good vs not recommended).
GreyChoose it when strength drives the design, or when weight is the constraint.
PETGChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
Grey vs PETG: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Shear Modulus
Hardness, Rockwell R
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
Light Transmission
Thermal
How each material carries heat and how hot it can run.
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Max Service Temperature (short-term)
Vicat Softening Point (B50)
Same in both: Thermal Conductivity 0.2 W/m·K0.12 BTU/hr·ft·°F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Surface Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Same in both: Thermal Diffusivity 0.1 mm²/s · Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every polymer grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Grey | PETG |
|---|---|---|
| CNC machining | — | Yes |
| Sheet metal | — | Yes |
| Default condition | Standard | Unfilled |
| Relative cost | $ Budget | $ Budget |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
Both are offered for Injection molding and 3D printing. Both take the same 12 finishes: Chrome Plating (Plastic), Conductive Coating, Dyeing (Nylon), EMI Shielding Coating, Painting, Primer Coating, Soft Touch Coating, Spray Painting, Tinted Coating, UV Coating, Vacuum Metallization, Waterproof Coating.
Grey vs PETG — frequently asked
Is Grey stronger than PETG?
Yes. Grey has a typical tensile strength of 55 MPa (7.98 ksi) against 50 MPa (7.25 ksi) for PETG — about 10% more.
Which is cheaper, Grey or PETG?
Both sit in the same relative cost tier ($, budget); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Grey or PETG?
PETG. Its machinability rates good (65/100) against fair (45/100) for Grey; for welding the order is PETG first (very good, 80/100) then Grey (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Grey and PETG side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.