PC/PBT vs PC-Si
Polymer · grade comparison
PC/PBT and PC-Si are both polymer grades. PC-Si is the stronger of the two: yield strength 58 MPa (8.41 ksi) against 52 MPa (7.54 ksi) for PC/PBT, about 12% more; tensile strength follows at 60 MPa (8.7 ksi) vs 53 MPa (7.69 ksi). PC-Si is harder — 80 Shore D against 76 Shore D for PC/PBT — which matters for wear surfaces and threads. PC-Si runs hotter in service (115°C vs 100°C continuous). On the shop floor, PC/PBT sits in a lower cost tier (standard, $$) than PC-Si (premium, $$$).
PC/PBTChoose it when cost is the deciding factor.
PC-SiChoose it when strength drives the design, or when surface hardness matters.
PC/PBT 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
Flexural Modulus
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell R
Shear Modulus
Bulk Modulus
Compressive Modulus
Shear Strength
Hardness, Rockwell M
Same in both: Elongation at Break 120%
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
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.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Comparative Tracking Index (CTI)
Same in both: Surface Resistivity 1×10¹⁵ Ω
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
Polishability
Mold Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Formability (cold)
Same in both: Weldability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 250 L/kg30 gal/lb
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Modulus of Resilience
Same in both: Specific Stiffness (E / density) 1.8 MN·m/kg · 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/PBT | PC-Si |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
PC/PBT vs PC-Si — frequently asked
Is PC-Si stronger than PC/PBT?
Yes. PC-Si has a typical yield strength of 58 MPa (8.41 ksi) against 52 MPa (7.54 ksi) for PC/PBT — about 12% more. Tensile strength is 60 MPa (8.7 ksi) vs 53 MPa (7.69 ksi).
Which is cheaper, PC/PBT or PC-Si?
PC/PBT is the lower-cost material: it sits in the standard tier ($$) while PC-Si is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose PC/PBT over PC-Si?
Pick PC/PBT when cost is the deciding factor. Pick PC-Si when strength drives the design, or when surface hardness matters.
Ready to make it?
Upload a CAD file and FabDigit prices the part in PC/PBT 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.