Castable Resin vs Flexible Resin
Polymer · grade comparison
Castable Resin and Flexible Resin are both polymer grades. Castable Resin is the stronger of the two: tensile strength 35 MPa (5.08 ksi) against 9 MPa (1.29 ksi) for Flexible Resin, about 3.9 times as much. In exchange, Flexible Resin is the more ductile: elongation 120% versus 6% for Castable Resin, and Castable Resin is harder (82 Shore D vs 30 Shore D). Castable Resin is stiffer (1.6 GPa vs 0.01 GPa) and Flexible Resin runs hotter in service (65°C vs 50°C continuous). On the shop floor, Castable Resin machines more easily (fair vs poor) and Flexible Resin sits in a lower cost tier (premium, $$$) than Castable Resin (high, $$$$).
Castable ResinChoose it when strength drives the design, or when the part is machined in volume.
Flexible ResinChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
Castable Resin vs Flexible Resin: 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)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Izod Impact, Notched
Hardness, Shore D
Shear Strength
Hardness, Shore A
Tear Strength
Compression Set (22 h, 70 °C)
Physical
Density and transition temperatures.
Density
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)
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Max Service Temperature (short-term)
Same in both: Min Service Temperature -20°C-4 °F · Limiting Oxygen Index 19%
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume 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.)
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Same in both: Embodied Carbon (primary production) 5.5 kg CO₂/kg · Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Shock Resistance Index
Same in both: Thermal Diffusivity 0.1 mm²/s
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 | Castable Resin | Flexible Resin |
|---|---|---|
| Injection molding | — | Yes |
| 3D printing | — | Yes |
| Default condition | — | Shore A 80 |
| Relative cost | $$$$ High | $$$ Premium |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | — | Yes |
| Conductive Coating | — | Yes |
| Dyeing (Nylon) | — | Yes |
| EMI Shielding Coating | — | Yes |
| Painting | — | Yes |
| Primer Coating | — | Yes |
| Soft Touch Coating | — | Yes |
| Spray Painting | — | Yes |
| Tinted Coating | — | Yes |
| UV Coating | — | Yes |
| Vacuum Metallization | — | Yes |
| Waterproof Coating | — | Yes |
Castable Resin vs Flexible Resin — frequently asked
Is Castable Resin stronger than Flexible Resin?
Yes. Castable Resin has a typical tensile strength of 35 MPa (5.08 ksi) against 9 MPa (1.29 ksi) for Flexible Resin — about 3.9 times as much.
Which is cheaper, Castable Resin or Flexible Resin?
Flexible Resin is the lower-cost material: it sits in the premium tier ($$$) while Castable Resin is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, Castable Resin or Flexible Resin?
Castable Resin. Its machinability rates fair (35/100) against poor (15/100) for Flexible Resin.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Castable Resin and Flexible Resin 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.