When PEEK Earns Its Price
PEEK (polyetheretherketone) is a high-performance engineering polymer that justifies its cost when at least one of three conditions applies: continuous operating temperatures above 150°C, exposure to aggressive chemicals, or requirements for ultra-low outgassing combined with mechanical strength. If none of these apply, POM, PPSU, or PTFE will do the same job at half the price or less.
PEEK vs. Common Alternatives
| Property | PEEK (natural) | POM (Delrin) | PPSU | PTFE |
|---|---|---|---|---|
| Continuous use temp | 250°C | 100°C | 180°C | 260°C |
| Tensile strength | 100 MPa | 70 MPa | 70 MPa | 25 MPa |
| Chemical resistance | Excellent | Good (not strong acids) | Good | Excellent |
| Friction / wear | Good | Excellent | Fair | Excellent (low friction) |
| Outgassing (ASTM E595) | Very low | Moderate | Low | Moderate |
| Material cost vs. aluminum | 5–10x | 0.3–0.5x | 2–3x | 1–2x |
What Makes PEEK Difficult to Machine
- Raw PEEK rod or plate costs 5–10 times as much as 6061-T6 aluminum per kilogram
- PEEK must be annealed before and sometimes during machining to prevent stress cracking and dimensional drift
- Tolerances below ±0.02 mm are harder to hold than in metal because PEEK expands with temperature and absorbs moisture
- Surface finish is sensitive to tool sharpness; dull tools leave visible smearing rather than clean cuts
When a Cheaper Plastic Works
- General-purpose jigs, spacers, and low-load structural parts: POM (Delrin) machines easily and holds tight tolerances at a fraction of the cost
- Steam sterilization or food contact at moderate temperature: PPSU (Radel) handles autoclave cycles without PEEK-level pricing
- Static seals, gaskets, and sliding bearings where strength is not critical: filled PTFE or UHMW offer excellent friction properties
Procurement Notes for PEEK Parts
When you do specify PEEK, confirm the grade: unfilled PEEK (e.g., Victrex 450G) is used for medical and food-contact parts, while 30% glass-filled PEEK offers higher stiffness and lower thermal expansion for structural applications. Request a material certificate with the resin batch number, and design wall thickness to at least 1 mm to avoid sink marks and warpage.
TruPart Precision, an ISO 9001 machine shop in Dongguan, machines PEEK and other engineering polymers with annealed stock and carbide tooling dedicated to plastics. PEEK is a remarkable material when the application calls for it, and specifying it where POM would work is a waste of budget.
Frequently Asked Questions
How much more does PEEK cost than POM?
PEEK raw material costs roughly 10–20 times more per kilogram than POM, and machining time is also longer due to annealing steps; finished PEEK parts typically cost 4–8 times an equivalent POM part.
Can PEEK hold metal-like tolerances?
With annealed stock and careful temperature control, PEEK can hold roughly ±0.02–0.03 mm on small features; tolerances tighter than ±0.01 mm are not reliable without grinding and environmental control.
What is the difference between 3D-printed PEEK and CNC-machined PEEK?
CNC-machined PEEK is fully dense isotropic material with predictable strength; 3D-printed PEEK has layer-bond weaknesses and lower strength, typically used for prototyping rather than production functional parts.
Does PEEK need to be annealed?
Yes, PEEK stock should be annealed before machining to relieve residual stresses from extrusion; thick sections may require an additional annealing step between roughing and finishing passes.