PEK BG (Bearing grade)
Heat-treated state
Pick for unlubricated bushings, seals, thrust washers and bearing cages running hot and dry.
Values for the BG condition
Other PEK grades and fills
PEK is listed in 3 conditions; see the grade overview at PEK.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
BGThis page Bearing grade | Pick for unlubricated bushings, seals, thrust washers and bearing cages running hot and dry. | — | 130 | 2 | — |
30 % short glass fiber reinforced | Choose for stiff, creep-resistant structural parts at 200–260 °C where electrical insulation must be preserved. | — | 168 | 2.5 | 102 HRM |
30 % short carbon fiber reinforced | Highest stiffness/strength and lowest CTE with improved thermal conductivity and static dissipation — for metal-replacement structural and semiconductor parts. | — | 220 | 1.8 | 105 HRM |
What is PEK BG?
PEK BG is PEK heat treated to BG — pick for unlubricated bushings, seals, thrust washers and bearing cages running hot and dry. PEK BG has a yield strength of 105 MPa (15.2 ksi) and a tensile strength of 130 MPa (18.9 ksi) — stronger than 97% of polymer grades. Elongation at break is 2% and the elastic modulus is 10 GPa (1.45 Msi). PEK BG has a density of 1.44 g/cm³ (0.052 lb/in³), heavier than 85% of polymer grades. Its glass-transition temperature is 157°C (315 °F).
Advantages
- Conducts heat well — 0.9 W/m·K (0.52 BTU/hr·ft·°F), better than 100% of polymer grades
- High strength — 105 MPa (15.2 ksi), better than 97% of polymer grades
- High service temperature — 260°C (500 °F), better than 97% of polymer grades
- Stiff — 10 GPa (1.45 Msi), better than 95% of polymer grades
- Good corrosion resistance — 90/100, better than 82% of polymer grades
Limitations
- High embodied carbon — 22 kg CO₂/kg, worse than 100% of polymer grades
- Limited ductility — 2%, worse than 95% of polymer grades
- Heavy — 1.44 g/cm³ (0.052 lb/in³), worse than 85% of polymer grades
PEK BG properties
Typical room-temperature values for PEK BG; 13 are specific to this condition. Other listed values are PEK reference data and may not represent this condition. Bars are the position among polymer grades.
Physical5
PEK BG has a density of 1.44 g/cm³ (0.052 lb/in³), heavier than 85% of polymer grades. Its glass-transition temperature is 157°C (315 °F).
Mechanical15
PEK BG has a yield strength of 105 MPa (15.2 ksi) and a tensile strength of 130 MPa (18.9 ksi) — stronger than 97% of polymer grades. Elongation at break is 2% and the elastic modulus is 10 GPa (1.45 Msi).
Thermal11
PEK BG is rated for continuous service to 260°C (500 °F). It conducts heat at 0.9 W/m·K (0.52 BTU/hr·ft·°F), better than 100% of polymer grades. Thermal expansion is 20 µm/m·K (11.1 µin/in·°F).
Electrical7
PEK BG is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 82% of polymer grades. UV resistance is fair.
Sustainability3
Producing a kilogram of PEK BG takes about 320 MJ of energy and emits 22 kg of CO₂ — more than 98% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PEK BG's machinability is good (55/100, worse than 64% of polymer grades); weldability good (55/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with PEK BG
Is PEK easy to machine?
Machines like PEEK but harder: sharp polycrystalline-diamond or carbide tooling, high speed with light feed, generous air/mist cooling, and stress-relief anneal near 200 °C before finishing to avoid post-machining distortion.
Can PEK be welded?
No solvent bonding; join by hot-plate, infrared, ultrasonic, laser transmission or induction welding at PAEK temperatures, or use high-temperature epoxy/polyimide adhesive after plasma or abrasive surface activation.
Can PEK be formed, bent or molded?
Inject or extrude at 390–415 °C melt with 180–220 °C tool temperature; dry pellets 3 h at 150 °C, use all-hardened high-temperature barrels and hot runners, and hold tool hot to develop full crystallinity (or anneal 200–250 °C for as-moulded amorphous skins).
What surface finishes work on PEK?
Takes fine machining and lapping to low Ra; can be laser marked and plasma-treated for printing or metallization, but is not paintable without primer and yellows in sunlight unless carbon-black pigmented.
PEK chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance.
| Element | Spec limit (wt %) |
|---|---|
| glass fiberGF30 variant only | ≈ 30 |
| carbon fiberCF30 variant only | ≈ 30 |
| PTFE + graphitebearing-grade lubricant package (with ~10 % carbon fiber) | ≈ 20 |
| poly(oxy-1,4-phenylene-carbonyl-1,4-phen1:1 ether:ketone backbone, CAS 27380-27-4; higher ketone content than PEEK | balance |
PEK BG — frequently asked
What is PEK BG used for?
PEK BG is typically used for aerospace insulation, high-temp bearings, downhole tooling components and high-performance electrical connectors. In short: higher temperature than PEEK; 260 °C continuous service; stiff at elevated temperature.
What is the yield strength of PEK BG?
PEK BG has a typical yield strength of 105 MPa (15.2 ksi) and a tensile strength of 130 MPa (18.9 ksi) — stronger than 97% of polymer grades. Strength varies by condition: see the 3 listed tempers.
Is PEK BG easy to machine?
Reasonably — machinability is rated good (55/100, worse than 64% of polymer grades). Machines like PEEK but harder: sharp polycrystalline-diamond or carbide tooling, high speed with light feed, generous air/mist cooling, and stress-relief anneal near 200 °C before finishing to avoid post-machining distortion.
Can PEK BG be welded?
Yes — weldability is rated good (55/100). No solvent bonding; join by hot-plate, infrared, ultrasonic, laser transmission or induction welding at PAEK temperatures, or use high-temperature epoxy/polyimide adhesive after plasma or abrasive surface activation.
What surface finishes work on PEK BG?
Takes fine machining and lapping to low Ra; can be laser marked and plasma-treated for printing or metallization, but is not paintable without primer and yellows in sunlight unless carbon-black pigmented.
Can PEK BG be formed, bent or molded?
Inject or extrude at 390–415 °C melt with 180–220 °C tool temperature; dry pellets 3 h at 150 °C, use all-hardened high-temperature barrels and hot runners, and hold tool hot to develop full crystallinity (or anneal 200–250 °C for as-moulded amorphous skins).
What is the maximum service temperature of PEK BG?
PEK BG is rated for continuous use to about 260°C (500 °F), and briefly to 320°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Victrex HT (PEK) grade data and processing guide — Victrex plc (2022)
- PAEK/PEK semi-finished stock shape properties — Ensinger (2023)
- Poly(aryl ether ketone)s — properties and processing — Hanser / Plastics Handbook (2019)
- CAMPUS / UL Prospector high-temperature thermoplastics datasets — CAMPUS Plastics (2024)
- ISO 527 / ISO 178 / ISO 75 test methods for plastics — ISO (2019)
- PEEK/PAEK (2026)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.