PEEK-Bearing-Grade vs PEK
Polymer · grade comparison
PEEK-Bearing-Grade and PEK are both polymer grades. PEEK-Bearing-Grade is the stronger of the two: yield strength 115 MPa (16.7 ksi) against 105 MPa (15.2 ksi) for PEK, about 10% more; tensile strength follows at 130 MPa (18.9 ksi) vs 110 MPa (16 ksi). In exchange, PEK is the more ductile: elongation 25% versus 2.5% for PEEK-Bearing-Grade. PEK is lighter (1.3 g/cm³ vs 1.44 g/cm³ for PEEK-Bearing-Grade) and PEEK-Bearing-Grade is stiffer (7.7 GPa vs 4 GPa). On the shop floor, PEK machines more easily (65 vs 55 out of 100) and PEK welds better (good vs poor).
PEEK-Bearing-GradeChoose it when strength drives the design.
PEKChoose it when the part is bent, formed or impact-loaded, or when weight is the constraint.
PEEK-Bearing-Grade vs PEK: 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)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Izod Impact, Notched
Same in both: Fracture Toughness (K_IC) 3.5 MPa·√m3.2 ksi·√in · Hardness, Shore D 87 Shore D · Hardness, Rockwell M 100 HRM
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (24 h)
Same in both: Water Absorption (Saturation) 0.4%
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
Volume Resistivity
Surface Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
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)
Polishability
Mold Shrinkage
Melt Flow Rate
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
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)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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 | PEEK-Bearing-Grade | PEK |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
PEEK-Bearing-Grade vs PEK — frequently asked
Is PEEK-Bearing-Grade stronger than PEK?
Yes. PEEK-Bearing-Grade has a typical yield strength of 115 MPa (16.7 ksi) against 105 MPa (15.2 ksi) for PEK — about 10% more. Tensile strength is 130 MPa (18.9 ksi) vs 110 MPa (16 ksi).
Which is cheaper, PEEK-Bearing-Grade or PEK?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, PEEK-Bearing-Grade or PEK?
PEK, by a small margin. Both rate good for machinability — 65/100 against 55/100 for PEEK-Bearing-Grade; for welding the order is PEK first (good, 55/100) then PEEK-Bearing-Grade (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in PEEK-Bearing-Grade and PEK 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.