BIIR vs IIR
Polymer · grade comparison
BIIR and IIR are both polymer grades. IIR is the stronger of the two: tensile strength 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for BIIR, about 9% more. IIR is the more ductile: elongation 600% versus 500% for BIIR. IIR is stiffer (0.01 GPa vs 0 GPa) and BIIR conducts heat better (0.22 W/m·K vs 0.13 W/m·K). On the shop floor, BIIR welds better (poor vs not recommended).
BIIRChoose it when it will be welded.
IIRChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
BIIR 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
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Hardness, Shore D
Compression Set (22 h, 70 °C)
Same in both: Hardness, Shore A 60 Shore A · Tear Strength 30 kN/m171 lbf/in
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Refractive Index
Same in both: Water Absorption (24 h) 0.5%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Min Service Temperature
Max Service Temperature (short-term)
Same in both: Specific Heat Capacity 1,900 J/kg·K0.45 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 180 µm/m·K100 µin/in·°F · Limiting Oxygen Index 20%
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Same in both: Dielectric Strength 25 kV/mm635 V/mil · Volume Resistivity 1×10¹⁵ Ω·cm
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.
Weldability
Formability (cold)
Mold Shrinkage
Mold Temperature (typ.)
Processing Melt Temperature (typ.)
Same in both: Machinability 30 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Embodied Water
Same in both: Embodied Energy (primary production) 105 MJ/kg45,142 BTU/lb · 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 | BIIR | IIR |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
BIIR vs IIR — frequently asked
Is IIR stronger than BIIR?
Yes. IIR has a typical tensile strength of 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for BIIR — about 9% more.
Which is cheaper, BIIR 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.
Which welds better, BIIR or IIR?
BIIR. Its weldability rates poor (25/100) against not recommended (5/100) for IIR.
Ready to make it?
Upload a CAD file and FabDigit prices the part in BIIR 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.