PEEK is the high-performance engineering plastic: about 100 MPa tensile, continuous service near 250°C, excellent chemical resistance and low outgassing. It is also expensive and it moves after machining — internal stress from the extrusion or moulding process relieves as material is removed, so precision parts need annealing and a finishing strategy.
| Tensile strength | 100 MPa |
|---|---|
| Yield strength | 90 MPa |
| Hardness | R126 (Rockwell M99) |
| Density | 1.30 g/cm³ |
| Elongation | 20% |
| Thermal conductivity | 0.25 W/m·K |
| Series | High-performance semi-crystalline polymer |
Typical values for the standard condition (PEEK (Polyetheretherketone)). Heat treatment, temper and product form move these numbers — confirm against the mill certificate for your order.
Continuous service temperature around 250°C
Excellent chemical resistance to most solvents and acids
Low outgassing, which suits vacuum and semiconductor applications
Biocompatible grades exist for medical use
Starting parameters for carbide tooling. These are the shop's working numbers, not brochure values — adjust for machine rigidity, tool geometry and workholding.
| Surface speed | 200–400 m/min |
|---|---|
| Feed per tooth | 0.10–0.30 mm/tooth |
| Tooling | Sharp polished carbide, 2–3 flute, high rake |
| Coolant | Air blast or mist; flood acceptable |
Machines like a hard plastic but moves after cutting. Stress relieve or anneal before finishing critical dimensions. Glass- or carbon-filled grades are highly abrasive — use diamond-coated or PCD tooling for any volume, or tool life collapses.
Material cost dominates. PEEK stock can run 12–18 times the price of aluminum by weight, and annealing adds a process step. Precision parts often require rough machine, anneal, finish — which is quoted as two operations.
For the full cost structure — material, programming, setup, cycle time, finishing and inspection — see CNC machining cost per hour, and for how price changes with quantity see machining by production volume.
Machining removes material that was balancing internal stress introduced when the stock was extruded or moulded. As that stress relieves, the part moves. The fix is to rough machine, anneal (stress relieve), then finish — and to specify that sequence rather than expecting a single machining operation to hold tight tolerances.
For unfilled PEEK, no — sharp polished carbide works well. For glass-filled or carbon-filled PEEK, yes for any real volume: the filler is highly abrasive and destroys standard carbide coatings quickly. Diamond-coated or PCD tooling is the practical choice.
Yes. PEEK withstands autoclave, gamma, ethylene oxide and most other common sterilization methods without significant degradation, which is one reason it is used in medical instruments and reusable surgical devices. Confirm the specific cycle against the grade datasheet for your application.
Food-contact grades of PEEK exist and are used in food processing equipment. Whether a specific grade is acceptable depends on the applicable regulation and the certification of that grade, so this should be confirmed with the material supplier rather than assumed from the polymer type.
Tell us the grade and temper, the quantity and what the part has to do. You get a line-item quote within 24 hours, with DFM feedback on anything that is raising the cost.