PAI vs PEEK
Polymer · grade comparison
PAI and PEEK are both polymer grades, both high performance plastic. PAI is the stronger of the two: tensile strength 152 MPa (22 ksi) against 100 MPa (14.5 ksi) for PEEK, about 52% more. In exchange, PEEK is the more ductile: elongation 30% versus 15% for PAI. PEEK is lighter (1.3 g/cm³ vs 1.42 g/cm³ for PAI) and PAI is stiffer (4.5 GPa vs 3.7 GPa). On the shop floor, PEEK machines more easily (very good vs good) and PEEK welds better (fair vs not recommended).
PAIChoose it when strength drives the design.
PEEKChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
PAI vs PEEK: 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Bulk Modulus
Yield Strength (0.2% offset)
Fracture Toughness (K_IC)
Hardness, Rockwell R
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Melting Temperature (Tm)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Min Service Temperature
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Max Service Temperature (short-term)
Vicat Softening Point (B50)
Same in both: Max Service Temperature (continuous) 250°C482 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Surface Resistivity
Comparative Tracking Index (CTI)
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)
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Melt Flow Rate
Same in both: Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: 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 | PAI | PEEK |
|---|---|---|
| 3D printing | — | Yes |
| Default condition | Unfilled (Electrical) | Virgin |
| Relative cost | $$$$$ Specialty | $$$$$ Specialty |
| Min. machined wall | 0.5 mm | 0.8 mm |
| Best machined surface | Ra 0.8 µm | Ra 0.8 µm |
| Conductive Coating | — | Yes |
| Dyeing (Nylon) | — | Yes |
| Primer Coating | — | Yes |
| Tinted Coating | — | Yes |
| Vacuum Metallization | — | Yes |
| Waterproof Coating | — | Yes |
Both are offered for CNC machining, Sheet metal and Injection molding. They share 6 finishes: Chrome Plating (Plastic), EMI Shielding Coating, Painting, Soft Touch Coating, Spray Painting, UV Coating.
PAI vs PEEK — frequently asked
Is PAI stronger than PEEK?
Yes. PAI has a typical tensile strength of 152 MPa (22 ksi) against 100 MPa (14.5 ksi) for PEEK — about 52% more.
Which is cheaper, PAI or PEEK?
Both sit in the same relative cost tier ($$$$$, specialty); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, PAI or PEEK?
PEEK. Its machinability rates very good (70/100) against good (60/100) for PAI; for welding the order is PEEK first (fair, 45/100) then PAI (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in PAI and PEEK 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.