High-Performance Thermoplastic for Demanding Engineering Applications
PEEK Material: Properties, Grades & Machining Guide
PEEK (polyetheretherketone) is a high-performance, semi-crystalline thermoplastic that holds its mechanical strength at continuous service temperatures up to 250°C, a combination no commodity plastic can match. Engineers specify PEEK material when metal is too heavy, standard plastics are too weak, and part failure is not an option.
This page gives you the working data you need: verified PEEK material properties with test standards, a grade-by-grade comparison, honest guidance on when PEEK is the wrong choice, and the machining realities that determine whether your part hits tolerance. Upload your CAD file for an instant quote and see exact pricing in under 60 seconds.
97 MPa
Tensile strength
250°C
Continuous service temp
3–7 days
Standard lead time
MOQ 1
Prototype to production
Polyetheretherketone Fundamentals
What Is PEEK Material?
PEEK material is a semi-crystalline thermoplastic in the polyaryletherketone (PAEK) family, prized for its rare combination of high-temperature resistance, chemical inertness, and mechanical strength. Developed for demanding engineering applications, it bridges the gap between metals and conventional plastics in aerospace, medical, and industrial components.
That semi-crystalline structure is the source of PEEK’s performance. The crystalline regions provide chemical resistance and high-temperature stability, while the amorphous regions deliver toughness and impact strength. The result is a PEEK plastic that resists steam, aggressive solvents, and cyclic loading in environments that destroy acetal, nylon, and polycarbonate.
Semi-Crystalline Structure
Crystalline regions provide chemical resistance and thermal stability
High-Temperature Stability
Continuous service up to 250°C with 343°C melting point
Chemical & Hydrolysis Resistance
Resists steam, solvents, acids, and thousands of sterilization cycles
Regulatory Certifications
UL 94 V-0 flame retardant, USP Class VI, and FDA compliant grades
Metal-to-Plastic Replacement
Bridges the gap between aluminum weight and conventional plastic performance.
Material Grades
PEEK Grades Compared
PEEK material grade selection changes stiffness, wear behavior, regulatory status, and machinability. These three grades cover the majority of part applications; bearing and medical grades are detailed below.
Unfilled PEEK
Unfilled (Natural) PEEK
Unfilled PEEK offers the best toughness and elongation of any grade, along with the cleanest machining behavior. It is FDA compliant in its natural state and the default starting point for prototypes and medical-adjacent parts.
- Best for: prototypes, medical devices, electrical components.
- Modulus: 3.5–4.1 GPa.
- Equivalent: Victrex 450G, TECAPEEK natural, Ketron 1000.
30% Glass-Filled
Glass-Filled PEEK (GF30)
Adding 30% glass fiber roughly doubles flexural modulus and cuts thermal expansion nearly in half. Specify GF30 when dimensional stability under heat and load matters more than impact strength.
- Best for: structural brackets, connector bodies, semiconductor fixtures.
- Modulus: ≈6.3 GPa.
- Note: abrasive filler wears carbide tools faster.
30% Carbon-Filled
Carbon-Filled PEEK (CF30)
Carbon fiber delivers the highest stiffness and strength of any standard grade, plus improved wear resistance and thermal conductivity. CF30 also provides static dissipation for electronics and ATEX-adjacent environments.
- Best for: high-load, wear-critical, static-dissipative parts.
- Modulus: ≈6.0 GPa.
- Tooling: requires PCD for economical tool life.
Engineering Data
PEEK Material Properties
Verified unfilled PEEK data with test standards engineers should cite on drawings and RFQs. Values align with Victrex and Ensinger datasheets.
Mechanical
97 MPa tensile strength, 3.5 GPa modulus. Retains stiffness across the operating range with excellent creep resistance for sustained loads.
Thermal
143°C Tg, 343°C melting point, 250°C continuous service. Low thermal conductivity (0.25 W/m·K) insulates but complicates machining.
Chemical
Resists nearly all organic and inorganic chemicals except concentrated sulfuric acid. Survives thousands of steam sterilization cycles.
Electrical
19 kV/mm dielectric strength, stable across temperature and frequency. Low moisture uptake keeps properties consistent in humid environments.
Flame Retardant
Inherently UL 94 V-0 without additives. Meets aerospace FST requirements and avoids halogenated outgassing in vacuum environments.
Biocompatibility
USP Class VI and ASTM F2026 implant grades. Radiolucent, steam/gamma/EtO sterilizable, and bone-matched modulus reduce stress shielding.
Grade Selection
PEEK Grade Comparison & Specialty Grades
Grade selection changes stiffness, wear behavior, regulatory status, and machinability. Compare all grades side by side, then review bearing and medical specialty grades below.
Grade Comparison Table
| Grade | Filler / Attribute | Tensile Modulus | Best For |
|---|---|---|---|
| Unfilled (natural) | None | 3.5–4.1 GPa | General-purpose parts, medical devices, electrical components |
| 30% Glass-filled (GF30) | Glass fiber | ≈6.3 GPa | Structural parts needing maximum stiffness and dimensional stability |
| 30% Carbon-filled (CF30) | Carbon fiber | ≈6.0 GPa | High-load, wear-critical, and static-dissipative parts |
| Bearing grade | PTFE, graphite, carbon | 3.0–4.5 GPa | Bushings, seals, thrust washers, wear rings |
| Medical / implant grade | Certified resin only | 3.5–4.1 GPa | Surgical instruments, implant trials, USP Class VI devices |
Not sure which grade fits your application? Every Baetro quote includes free DFM feedback. Our engineers flag grade mismatches, tolerance risks, and cost-saving alternatives before we machine your first part. Upload your CAD file to start the review.
Bearing & Medical Grades
Bearing-Grade PEEK: Bearing grades blend PTFE, graphite, and carbon fiber for the lowest friction coefficient and wear rate in the PEEK family. Use them for unlubricated bushings, seals, valve seats, and thrust washers, especially where metal bearings would gall or where lubrication is prohibited.
Medical-Grade PEEK: Medical-grade PEEK meets USP Class VI biocompatibility requirements, and implantable variants conform to ASTM F2026, the standard specification for surgical implant PEEK. It is radiolucent (transparent to X-rays), sterilizable by steam, gamma, and EtO, and its elastic modulus sits closer to cortical bone than titanium, reducing stress shielding in orthopedic and spinal implants.
Mechanical
97 MPa
Tensile strength (yield) per ASTM D638, comparable to structural metals on a strength-to-weight basis.
Thermal
343°C
Melting point per ASTM D3418, with 143°C glass transition and 250°C continuous service rating.
Performance
250°C
Continuous service temperature per UL 746B, surviving autoclave and engine-adjacent environments.
Physical
1.30 g/cm³
Density per ASTM D792, roughly half that of aluminum, enabling significant weight reduction.
Verified Data
Complete PEEK Material Properties
Consolidated property data for unfilled PEEK resin with test standards engineers should cite on drawings and RFQs. Values align with published datasheets from Victrex and Ensinger.
| Property | Metric | Imperial | Test Standard |
|---|---|---|---|
| Tensile strength (yield) | 97 MPa | 14,100 psi | ASTM D638 |
| Tensile modulus | 3.5 GPa | 508 ksi | ASTM D638 |
| Flexural modulus | 4.1 GPa | 595 ksi | ASTM D790 |
| Elongation at break | 20–60% | N/A | ASTM D638 |
| Hardness | 85–90 Shore D | N/A | ASTM D2240 |
| Melting point | 343°C | 649°F | ASTM D3418 |
| Glass transition temperature (Tg) | 143°C | 289°F | ASTM D3418 |
| Heat deflection temp @ 1.8 MPa | 160°C | 320°F | ASTM D648 |
| Continuous service temperature | 250°C | 482°F | UL 746B |
| Thermal conductivity | 0.25 W/m·K | 1.7 BTU·in/(hr·ft²·°F) | ASTM C177 |
| Density | 1.30 g/cm³ | 0.047 lb/in³ | ASTM D792 |
| Water absorption (24 hr) | 0.1% | N/A | ASTM D570 |
| Dielectric strength | 19 kV/mm | 483 V/mil | ASTM D149 |
| Flammability | UL 94 V-0 | N/A | UL 94 |
Property values reflect published producer datasheets; verify critical values against the specific grade and lot certification for your application. Need properties for filled grades? Contact our engineers for GF30, CF30, and bearing-grade datasheets.
Machining Guidance
Machining PEEK: What Engineers Need to Know
PEEK material machines more like brass than like a typical plastic, but only when the process respects its quirks. Three factors separate accurate PEEK parts from warped scrap.
Machining Recommendations
| Parameter | Unfilled PEEK | Filled Grades (GF30/CF30) |
|---|---|---|
| Recommended tooling | Sharp polished carbide | PCD (polycrystalline diamond) |
| Cooling method | Air or mist cooling | Air or mist cooling |
| Annealing cycle | 150–200°C controlled | 150–200°C controlled |
| Achievable tolerance | ±0.001″ (±0.025 mm) | ±0.001″ (±0.025 mm) |
| Chip type | Stringy, continuous | Abrasive, dust-generating |
| Common failure mode | Thermal softening, smearing | Tool wear, fiber pull-out |
With annealing, sharp tooling, and temperature-controlled finishing passes, CNC machined PEEK holds ±0.001 in. on critical features. Our PEEK CNC machining services run this process daily, verified by CMM inspection with reports shipped alongside every order.
Critical Process Factors
- Tooling Selection: Sharp, polished carbide tooling handles unfilled PEEK economically. For glass- and carbon-filled grades, switch to PCD tooling; the abrasive filler wears carbide edges within a few parts. Positive rake angles and generous chip clearance prevent the stringy, continuous chips PEEK likes to produce.
- PEEK Machining Temperature: At 0.25 W/m·K, PEEK moves heat roughly 1/400th as fast as aluminum. Heat generated at the cutting edge stays in the cut zone, softening the surface and baking in residual stress. Keep temperature in check with sharp tools, conservative feed rates, and air or mist cooling rather than flood coolant where moisture uptake is a concern.
- Annealing and Stress Relief: Stock shapes carry molding stress, and machining adds more. For tolerances tighter than ±0.005 in., anneal PEEK between roughing and finishing operations, typically a controlled cycle at 150–200°C. Skipping annealing is the single most common cause of PEEK parts drifting out of tolerance after inspection.
- Achievable Tolerances: With annealing, sharp tooling, and temperature-controlled finishing passes, CNC machined PEEK holds ±0.001 in. on critical features. For higher volumes, PEEK injection molding becomes cost-effective once tooling amortizes across the run.
Material Selection
When PEEK Is (and Isn’t) the Right Material
Honest material selection saves more money than aggressive negotiation. PEEK material is the right call when metal is too heavy, standard plastics are too weak, and part failure is not an option.
PEEK Is the Right Choice
- Continuous service exceeds 150°C, or autoclave/steam sterilization is required
- The part faces aggressive chemicals, sour gas, or high-pressure steam
- Biocompatibility (USP Class VI) or implant certification (ASTM F2026) is mandatory
- Metal replacement demands high strength at low weight with electrical insulation
PEEK Is the Wrong Choice
If your application does not clearly need PEEK’s thermal, chemical, or regulatory performance, lower-cost alternatives often deliver better value.
- Service stays below 100°C and loads are moderate. POM (acetal) or nylon deliver 80% of the function at 10–20% of the PEEK material cost
- The design is cost-driven with cosmetic requirements. Polycarbonate or ABS machine beautifully for far less
- Thin-walled molded features can’t tolerate the annealing budget tight PEEK tolerances require; at production volumes, PEEK injection molding may suit the geometry better
Material cost guidance: Unfilled PEEK stock shapes typically run $90–150/kg, and significantly more for certified medical grades. If your part doesn’t clearly need PEEK’s performance, our engineering materials guide compares lower-cost alternatives side by side.
Applications
PEEK Material Applications by Industry
PEEK material earns its cost in applications where one of three things fails conventional plastics: heat, chemicals, or regulatory scrutiny.
Industry
Aerospace & Defense
Brackets, bushings, cable insulation, and clamp blocks replace aluminum at a fraction of the weight. PEEK’s FST (flame, smoke, toxicity) performance satisfies cabin requirements, and its fatigue resistance suits cyclic airframe loads.
Industry
Medical Devices
Surgical instrument handles, dental healing caps, implant sizing trials, and sterilization trays use PEEK’s steam-cycle durability and biocompatibility. Full material traceability and inspection reporting for FDA-regulated customers.
Industry
Semiconductor & Electronics
Wafer handling end effectors, test sockets, and insulating hardware exploit PEEK’s purity (low outgassing, low ionic contamination) and stable dielectric properties.
Industry
Oil, Gas & Energy
Downhole seals, valve seats, and compressor components survive sour gas, high-pressure steam, and 200°C+ service that destroys elastomers and standard thermoplastics.
Industry
Automotive
Transmission thrust washers, pump wear rings, and bearing cages replace metal where weight, noise, or lubricant-free operation matters in engine-adjacent environments.
Industry
Industrial Equipment
Bushings, seals, thrust washers, and wear rings for machinery and automation systems, especially where metal bearings would gall or where lubrication is prohibited.
Manufacturing Volume
PEEK Manufacturing: Prototypes to Production
CNC milling enables a seamless transition from prototype to production—same process, same quality, scaled to your volume. For higher volumes, injection molding becomes cost-effective.
Prototype PEEK Milling
Fast parts for design validation without tooling commitments.
- No minimum order quantity—order 1 piece
- 3–7 day standard lead times
- Same tolerances and quality as production parts
- Free DFM feedback for manufacturability issues
- Multiple material options for design comparison
Low-Volume Production
10–1,000 parts with cost-effective CNC milling and flexible scheduling.
- Economical for volumes up to 1,000+ parts depending on complexity
- Consistent quality across batches with documented processes
- Easy design changes between runs without tooling modification
- Ideal for product launches, limited editions, and bridge production
High-Volume & Injection Molding
Optimized programs, in-process inspection, and dedicated machine capacity ensure throughput for larger production runs.
- Cycle time optimization for high-volume CNC efficiency
- In-process and final inspection routines
- Dedicated machines for consistent throughput
- PEEK injection molding available for production volumes where tooling amortizes
How it works
Our PEEK Machining Process
Working with Baetro is straightforward. Here is the controlled process from CAD file upload to finished PEEK parts.
Upload Your CAD File
Send your design in STEP, IGES, SolidWorks, or Parasolid format. STEP files are preferred for CNC milling projects.
Receive Quote + DFM Feedback
In under 60 seconds, review pricing, lead time, and manufacturability notes for thin walls, deep pockets, or inaccessible features.
Select Grade & Material
Choose unfilled, GF30, CF30, bearing, or medical grade. Your project manager confirms the order and production schedule.
CNC Machining + Annealing
Parts are CNC milled to approved programs with annealing between roughing and finishing to relieve stress and hold tolerance.
Final CMM Inspection
Every part receives final inspection on CMM equipment, with surface finish verification when required by your specification.
Ship with Documentation
Parts are packaged with inspection reports, material certifications, and required documents, then shipped worldwide by express carrier.
Cost considerations
PEEK Cost Factors & Alternatives
Understanding what drives PEEK material costs helps you make informed design and material decisions.
- Material Grade: Unfilled PEEK stock shapes typically run $90–150/kg. Filled and certified medical grades are priced significantly higher.
- Part Complexity: Deep pockets, thin walls, and multiple setups increase machining time and cost. DFM feedback identifies simplifications.
- Tolerance Requirements: Precision tolerances (±0.001″) require stress-relief annealing between operations, adding cycle time and cost.
- Tooling Costs: Glass- and carbon-filled grades require PCD tooling for economical tool life, increasing initial setup investment.
- Order Quantity: Low volumes have higher per-part cost due to setup; high volumes reduce per-part cost and may qualify for injection molding.
- Alternative Materials: For service below 100°C with moderate loads, POM (acetal), nylon, polycarbonate, or ABS deliver 80% of function at 10–20% of PEEK cost.
FAQ
PEEK Material FAQs
Answers to common questions about PEEK material properties, grades, machining, tolerances, costs, and regulatory status.
Is PEEK material FDA approved?
Specific unfilled PEEK grades are FDA compliant for food and body contact, and medical grades meet USP Class VI biocompatibility requirements. Implantable PEEK must conform to ASTM F2026. “FDA approved” applies to specific certified grades, not PEEK generically. Always specify the certification your application requires on the RFQ.
What temperature can PEEK withstand?
PEEK material handles continuous service at 250°C (482°F) per UL 746B, with a glass transition at 143°C and melting point at 343°C. Short excursions above 250°C are survivable, but mechanical properties decline predictably as you approach and pass Tg.
Is PEEK stronger than aluminum?
Not in absolute terms. Unfilled PEEK’s 97 MPa tensile strength falls well short of 6061-T6 aluminum at 310 MPa. On a strength-to-weight basis the gap narrows considerably, and carbon-filled PEEK closes it further. PEEK replaces aluminum where weight, insulation, corrosion, or radiolucency matter more than raw strength.
How much does PEEK material cost?
Unfilled PEEK stock shapes typically run $90–150/kg, with filled and certified medical grades priced higher. Material cost is only part of part cost, though; cycle time, scrap risk, and annealing steps shape the final price. An instant quote prices your specific geometry rather than a generic per-kilogram figure.
Can PEEK be CNC machined to tight tolerances?
Yes. With stress-relief annealing, sharp carbide or PCD tooling, and controlled finishing passes, PEEK machines to ±0.001 in. on critical dimensions. The two failure modes, thermal distortion and post-machining stress relaxation, are both process problems, not material limits.
What is the difference between PEEK and PAEK?
PAEK (polyaryletherketone) is the polymer family; PEEK is its most common member. Siblings like PEK, PEKK, and PEKEKK shift the ketone-to-ether ratio to raise glass transition and melting points. PEKEKK, for example, reaches a 165°C Tg, but at higher cost and narrower processing windows.
Quote-ready manufacturing
Get PEEK Parts Machined to Spec
You now have the PEEK material property data, grade differences, and machining realities that determine part success. The next step is pricing your actual design.
Baetro machines PEEK parts in 3–7 days with no minimum order quantity. Every quote includes free DFM review. Our engineers check grade selection, wall thicknesses, tolerance stack-ups, and stress-relief requirements before cutting begins. Every shipment includes CMM inspection reports and full material traceability from our ISO 9001 and AS9100 certified facility.
Parts ship in 3–7 days. No minimum order quantity. ISO 9001 & AS9100 certified.
Not ready to upload a file? Contact our engineers to discuss your project, review material options, or get guidance on grade selection.