PC/PET vs PC-Si
Polymer · grade comparison
PC/PET and PC-Si are both polymer grades. PC-Si is the stronger of the two: yield strength 58 MPa (8.41 ksi) against 53 MPa (7.69 ksi) for PC/PET, about 9% more; tensile strength follows at 60 MPa (8.7 ksi) vs 55 MPa (7.98 ksi). PC-Si runs hotter in service (115°C vs 100°C continuous).
PC-SiChoose it when strength drives the design, or when the part sees heat.
PC/PET vs PC-Si: 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)
Compressive Strength
Flexural Strength
Izod Impact, Notched
Hardness, Rockwell M
Shear Modulus
Bulk Modulus
Compressive Modulus
Shear Strength
Hardness, Shore D
Same in both: Elongation at Break 120% · Flexural Modulus 2.2 GPa0.32 Msi · Hardness, Rockwell R 118 HRR
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (Saturation)
Refractive Index
Same in both: Water Absorption (24 h) 0.15%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
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
Vicat Softening Point (B50)
Limiting Oxygen Index
Max Service Temperature (short-term)
Electrical
Conductivity and insulation.
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Surface Resistivity
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in · Volume Resistivity 1×10¹⁶ Ω·cm · Comparative Tracking Index (CTI) 250 V
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
UV / Weathering Resistance
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Polishability
Mold Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Formability (cold)
Same in both: Machinability 60 / 100 · Weldability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | PC/PET | PC-Si |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
PC/PET vs PC-Si — frequently asked
Is PC-Si stronger than PC/PET?
Yes. PC-Si has a typical yield strength of 58 MPa (8.41 ksi) against 53 MPa (7.69 ksi) for PC/PET — about 9% more. Tensile strength is 60 MPa (8.7 ksi) vs 55 MPa (7.98 ksi).
Which is cheaper, PC/PET or PC-Si?
Both sit in the same relative cost tier ($$$, premium); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose PC/PET over PC-Si?
Pick PC-Si when strength drives the design, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in PC/PET and PC-Si 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.