PEEK Back-up Rings & Bearing Cages Range
Seals and bearings fail most often at their edges — the point where an elastomer seal is squeezed into a gap, or where rolling elements lose their spacing and begin to wear. PEEK back-up rings and bearing cages are engineered precisely to prevent these two failure modes, and they are among the highest-value precision parts a machining specialist can supply. This guide covers the PEEK back-up ring and bearing cage product range from Dalian Luyang Technology, the sizes and tolerances you should specify, and how to choose the right virgin or reinforced PEEK grade.
1. Why PEEK Back-up Rings?
A back-up ring sits behind an O-ring or elastomer seal to stop the soft seal extruding into the diametral gap under pressure. In high-pressure hydraulic, pneumatic, and process-valve service, an unsupported seal extrudes, shreds, and fails quickly. A precisely fitted PEEK back-up ring:
- Bridges the extrusion gap so the elastomer stays in its groove
- Withstands sustained pressure at ~260 °C continuous rating
- Slides against moving parts with low friction and low wear
- Resists the chemicals that dissolve or swell many seal neighbours
PEEK is the preferred back-up ring material over harder plastics because it combines high compressive strength, low friction, dimensional stability, and wear resistance.
2. PEEK Bearing Cages: The Role of the Cage
The bearing cage (retainer/separator) holds rolling elements at correct spacing, preventing them from colliding and redistributing load evenly. PEEK cages offer advantages over stamped-metal or phenolic cages:
| Cage property | Benefit in service |
|---|---|
| --- | --- |
| Low density (~1.30 g/cm³) | Lower inertia, less centrifugal force at high speeds |
| Low friction | Reduced wear and heat at the ball/finger interface |
| Chemical & corrosion resistance | Operates in lubricants and media that attack metal cages |
| High-temperature stability | Near ~260 °C continuous, holds geometry |
| Self-lubricating polymers | Improves break-in and dry-running behaviour |
For applications ranging from high-speed machine spindles to submersible pumps and aerospace actuators, a machined PEEK cage keeps the rolling-element set aligned while adding negligible weight.
3. Typical Sizes & Tolerances
Back-up rings and bearing cages are machined-to-print parts, so dimensioning is your key control. A representative guidance table (specific figures are application-dependent):
| Parameter | Back-up ring | Bearing cage |
|---|---|---|
| --- | --- | --- |
| Typical sizes | ID 10 mm – 500 mm+ | OD 20 mm – 600 mm+ |
| Radial wall types | Burr-free, split/one-piece | One-piece, windowed |
| Machined tolerance (typical) | ±0.02 mm on ID/OD | ±0.02–0.05 mm on pockets |
| Concentricity / run-out | ≤0.05 mm (varies) | ≤0.05 mm |
| Edge condition | Break sharp edges, deburr | Smooth pockets, no fibre tearing |
| Surface finish | Ra 0.4–1.6 µm | Ra 0.8–1.6 µm |
> Tolerance and clearance must be validated against your groove/bearing envelope and operating temperature. PTFE cages offer the lowest friction and can run at ~260 °C; PEEK gives higher strength and stiffness — the table below helps you choose.
4. Grade Selection Guide
Not all PEEK grades suit both parts equally. Match the grade to the dominant load and temperature:
| Application need | Recommended material/grade | Reason |
|---|---|---|
| --- | --- | --- |
| Standard high-pressure back-up ring | Unfilled PEEK (e.g., LY-100/101/102 series) | Strength, low friction, ~260 °C, easy machining |
| High-extrusion-gap / wear resistance | Wear-grade PEEK (e.g., LY-205-type CFR-PEEK) | Low friction ~0.13, low wear, higher tensile ~202 MPa |
| Wet / chemical / electrolyzer service | PTFE sealing grades (LY-401/403) | Chemical inertness for pressure seals |
| Ultra-high-temperature dry service | PI (e.g., LY-601) | ~360 °C continuous, very low wear |
| Lowest friction running surface | PTFE (industry 0.05–0.10) | Absolute lowest sliding coefficient |
5. Manufacturing & Sourcing Checks
- Machinability: pure PEEK is clean-machining; carbon/glass-filled grades are abrasive — use diamond tooling and sharp feeds (see the full machining guide).
- Deburring & edge control: a burr or sharp edge on a back-up ring cuts the seal. Specify deburring and inspection.
- Certification: for critical sealing, request material certificates, dimensional inspection reports, and ISO 9001 (and ISO 13485 where applicable) documentation from your supplier.
- Prototyping: always validate geometry and interference on a sample batch before quantity production.
Frequently Asked Questions
- What is a PEEK back-up ring used for? A PEEK back-up ring is fitted behind an O-ring/elastomer seal to prevent the seal from extruding into the diametral gap under pressure — extending seal life in high-pressure hydraulic and process-valve service.
- Why use PEEK for bearing cages? PEEK cages are light (~1.30 g/cm³), low-friction, corrosion-resistant, and stable to ~260 °C, so they reduce inertia, wear, and heat in high-speed and aggressive-lubricant bearing applications.
- Which PEEK grade should I choose for a back-up ring? For standard service, an unfilled PEEK grade (e.g., LY-100/101/102). Where wear and higher tensile strength are critical, a wear-grade CFR-PEEK (e.g., LY-205-type, ~202 MPa tensile, friction ~0.13) is preferred; verify against your pressure/temperature envelope.
Related Topics
- LY 401 / 403 / 405 PTFE Sealing & Electrolyzer Gasket Grades
- PEEK vs PTFE vs Polyimide for Sealing: Which Material, When?
- How to Choose a PEEK Parts Manufacturer / Supplier
Dalian Luyang Technology Development Co., Ltd. (www.newmaterialchina.com) manufactures PEEK, PI, and PTFE precision parts — seals, inserts, machined components, and electrolyser frames — under ISO 9001 and ISO 13485. Established 2006. Contact: liyulong@luyangkeji.com · WhatsApp +86 15989781752. This guide is educational reference material; always verify against your chosen grade's official datasheet.