CIIR vs IIR
Polymer · grade comparison
CIIR and IIR are both polymer grades. IIR is the more ductile: elongation 600% versus 500% for CIIR. IIR is lighter (1.12 g/cm³ vs 1.18 g/cm³ for CIIR) and IIR is stiffer (0.01 GPa vs 0 GPa).
CIIRChoose it when the part sees heat.
IIRChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
CIIR vs IIR: 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
Shear Modulus
Bulk Modulus
Poisson's Ratio
Elongation at Break
Shear Strength
Hardness, Shore D
Compression Set (22 h, 70 °C)
Same in both: Tensile Strength (Ultimate) 12 MPa1.7 ksi · Hardness, Shore A 60 Shore A · Tear Strength 30 kN/m171 lbf/in
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Same in both: Specific Heat Capacity 1,900 J/kg·K0.45 BTU/lb·°F
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.
Formability (cold)
Mold Shrinkage
Processing Melt Temperature (typ.)
Weldability
Same in both: Machinability 30 / 100 · Mold Temperature (typ.) 175°C347 °F
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 5%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 0 MN·m/kg · 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 | CIIR | IIR |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
CIIR vs IIR — frequently asked
What is the difference between CIIR and IIR?
CIIR and IIR are both polymer grades. IIR is the more ductile: elongation 600% versus 500% for CIIR. IIR is lighter (1.12 g/cm³ vs 1.18 g/cm³ for CIIR) and IIR is stiffer (0.01 GPa vs 0 GPa).
Which is cheaper, CIIR or IIR?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
When should I choose CIIR over IIR?
Pick CIIR when the part sees heat. Pick IIR when the part is bent, formed or impact-loaded, or when weight is the constraint.
Ready to make it?
Upload a CAD file and FabDigit prices the part in CIIR and IIR 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.