PEEK (Polyether Ether Ketone) – Technical Material Specification
Comprehensive technical specification for PEEK including mechanical properties, standard Canadian stock sizes, machinability parameters, common defects, and storage guidelines.
Material Overview & Common Uses
PEEK (Polyether Ether Ketone) is a high-performance semi-crystalline thermoplastic known for its exceptional mechanical strength, thermal stability (continuous service up to 260°C), chemical resistance, and low moisture absorption. It is widely used in demanding applications such as aerospace components, medical implants, semiconductor wafer handling, oil & gas seals, and high-temperature electrical insulators. In Canadian fabrication shops, PEEK is often specified for parts requiring tight tolerances, wear resistance, and exposure to aggressive chemicals or steam sterilization.
Core Technical Properties & Sizing
| Property | Value |
|---|---|
| Density | 1.32 g/cm³ (ASTM D792) |
| Tensile Strength | 90–100 MPa (ASTM D638) |
| Flexural Modulus | 3.6–4.1 GPa (ASTM D790) |
| Izod Impact (notched) | 80–100 J/m (ASTM D256) |
| Melting Point | 343°C (ASTM D3418) |
| Glass Transition Temperature | 143°C (ASTM E1356) |
| CTE | 47 µm/m·°C (ASTM E831) |
| Water Absorption (24 hr) | 0.1% (ASTM D570) |
| Flammability Rating | V-0 (UL 94) |
| Standard Canadian Stock Sizes | Sheets: 1220 mm × 2440 mm (4' × 8') in thicknesses 1.5 mm, 3 mm, 6 mm, 12 mm, 25 mm; Rods: 6 mm to 150 mm diameter × 1000 mm length; Tubes: various ID/OD per ASTM F2026 |
| Tolerances | Thickness: ±0.13 mm (sheets ≤6 mm), ±0.25 mm (6–25 mm); Flatness: 0.5 mm per 300 mm (0.020″ per foot); Rod diameter: ±0.05 mm for precision grades |
Machinability, Tooling & Feeds
| Operation | Speed | Feed | Depth of Cut | Notes |
|---|---|---|---|---|
| Turning | 150–250 m/min | 0.1–0.3 mm/rev | 0.5–2.0 mm | Use carbide or PCD tools; flood coolant recommended |
| Milling | 8,000–15,000 RPM | 0.05–0.15 mm/tooth | 0.5–1.5 mm radial | Avoid climb milling on thin sections; use air blast |
| Drilling | — | — | — | Parabolic flute drills, point angle 118°–130°, peck cycle for depths >3× diameter |
| General | Tool material: carbide or PCD. Coolant: flood or air blast. Avoid sharp internal corners (use radii ≥0.5 mm). PEEK is notch‑sensitive. | |||
Common Defects & Quality Control
| Defect / QC Check | Description / Acceptable Limit |
|---|---|
| Surface cracking / crazing | From excessive heat or aggressive machining; inspect under 5× magnification |
| Delamination | In extruded sheets due to improper processing |
| Porosity / voids | In thick sections from gas entrapment; ≤1% area per 100 cm² |
| Warpage | From uneven cooling or residual stress; ≤0.5 mm over 300 mm |
| Discoloration (yellowing) | Thermal degradation; reject if visible |
| Density verification | Water displacement per ASTM D792 |
| Tensile test | Sample coupons per ASTM D638 |
| Surface defects | Scratches ≤0.1 mm depth per ASTM D6262 |
| DSC analysis | Crystallinity target 30–35% |
Storage, Handling & Racking Guidelines
- Store in clean, dry environment at 15–25°C (59–77°F) away from direct UV light and heat sources.
- Use vertical racking for sheets to prevent warpage; support rods horizontally on padded racks to avoid bending.
- Keep material sealed in original packaging or polyethylene wrap to minimise dust and moisture absorption.
- Avoid stacking heavy loads on top of PEEK stock.
- For long-term storage, maintain relative humidity below 50%.
- Rotate stock FIFO to prevent age-related property changes.
- Handle with clean gloves to avoid oil contamination that can affect bonding or machining.