PEEK CNC Machining: The Premium Metal Replacement
PEEK is the plastic you use when no other plastic works. It handles 480°F continuous. It resists nearly every chemical on the planet. It has the best strength-to-weight ratio of any plastic. And it is FDA biocompatible for medical implants.
What is PEEK machining?
PEEK machining is the precision CNC fabrication of custom parts using Polyether Ether Ketone, a high-performance semi-crystalline thermoplastic rated for continuous service temperatures up to 480°F (250°C). Due to its high raw material cost ($200–$800/lb), PEEK is specialized for aerospace, semiconductor, and medical implant applications as a direct replacement for stainless steel and titanium, providing a 50% to 80% weight reduction and immunity to corrosive chemicals.
The full name is polyether ether ketone. PEEK is a semi-crystalline thermoplastic that sits at the very top of the polymer pyramid. It replaces stainless steel, titanium, and aluminum in applications where you need less weight, no corrosion, and no lubrication.
The catch? PEEK raw stock costs $200–$800 per pound. That is 10–20x more than Delrin or nylon 6/6. But in the right application, PEEK saves money by lasting longer, removing maintenance, and cutting assembly weight.
At RivCut, we machine PEEK 450G, PEEK GF30, PEEK CF30, and PEEK-HT. Upload your CAD file and get a quote in minutes. Most PEEK parts cost $150–$600 and ship in 5–7 business days.
PEEK Material Properties
Here are the numbers that matter when you design with PEEK.
| Property | PEEK 450G (Unfilled) | PEEK CF30 (Carbon-Filled) |
|---|---|---|
| Tensile Strength | 16 ksi (110 MPa) | 24 ksi (165 MPa) |
| Yield Strength | 14 ksi (97 MPa) | 21 ksi (145 MPa) |
| Hardness | Rockwell M99 | Rockwell M102 |
| Max Continuous Temp | 480°F (250°C) | 480°F (250°C) |
| Density | 0.047 lb/in³ (1.30 g/cm³) | 0.050 lb/in³ (1.40 g/cm³) |
| Chemical Resistance | Nearly all chemicals | Nearly all chemicals |
| Thermal Conductivity | 0.25 W/mK | 0.92 W/mK |
| Moisture Absorption | 0.50% | 0.30% |
| FDA Biocompatible | Yes (ISO 10993) | Varies by grade |
PEEK Grades We Machine
Each PEEK grade is engineered for distinct performance demands. Selecting the correct grade optimizes both component life and production costs.
PEEK Grade Specification Viewer
Select a grade below to view mechanical properties, comparative ratings, and specifications
PEEK 450G Specifications
PEEK 450G (Unfilled) is the standard, purest grade of Polyether Ether Ketone. It offers the highest ductility, impact toughness, and chemical resistance among all grades. Because it is free from reinforcing additives, it is the only grade certified for long-term medical implant devices (such as PEEK-OPTIMA) and is the premier choice for semiconductor wet-bench wafer seals and chemical processing components.
PEEK GF30 Specifications
PEEK GF30 is reinforced with 30% glass fibers, which increases its flexural modulus by more than 50% and dramatically lowers its coefficient of thermal expansion. It is highly dimensional stable and serves as an excellent electrical insulator. Best for structural housings, chemical manifold plates, and high-temp probe fixtures.
PEEK CF30 Specifications
PEEK CF30 features 30% carbon fiber reinforcement, offering the highest strength-to-weight ratio and stiffness of any machineable thermoplastic. With a tensile strength of 24 ksi (comparable to structural aluminum), it is a superior metal replacement. The carbon content also provides wear resistance and thermal dissipation. Best for aerospace brackets, pump impellers, and wear pads.
PEEK-HT Specifications
PEEK-HT is chemically optimized to extend continuous operational limits beyond 500°F (260°C). It maintains exceptional mechanical strength and chemical stability at elevated temperatures where standard PEEK begins to soften. Best for geothermal tools, downhole oil/gas sensors, and medical autoclave chambers.
PEEK vs Other Materials
PEEK competes with both plastics and metals. Here is how it stacks up.
PEEK vs Engineering Plastics
| Property | PEEK 450G | Delrin (POM) | Ultem (PEI) | Nylon 6/6 |
|---|---|---|---|---|
| Tensile Strength | 16 ksi | 10 ksi | 15 ksi | 12 ksi |
| Max Temp | 480°F | 180°F | 340°F | 220°F |
| Chemical Resistance | Excellent | Good | Good | Fair |
| Moisture Absorption | 0.50% | 0.22% | 0.25% | 2.5% |
| Biocompatible | Yes (ISO 10993) | FDA food-safe | No | No |
| Cost per Part | $150–$600 | $65–$250 | $100–$400 | $60–$200 |
PEEK vs Metals
| Property | PEEK CF30 | Stainless 316 | Titanium Ti-6Al-4V | Aluminum 6061-T6 |
|---|---|---|---|---|
| Density | 0.050 lb/in³ | 0.290 lb/in³ | 0.160 lb/in³ | 0.098 lb/in³ |
| Weight Savings | Baseline | 5.8x heavier | 3.2x heavier | 2x heavier |
| Corrosion | Immune | Resists most | Resists most | Needs anodizing |
| Lubrication Needed | No | Yes | Yes | Yes |
| Electrical Insulation | Yes | No (conductive) | No (conductive) | No (conductive) |
| Radiolucent (X-ray clear) | Yes | No | No | No |
Choose PEEK when you need high temperature, chemical resistance, weight savings, or biocompatibility. It costs more than other plastics but less than the metal assembly it often replaces.
Choose Delrin when temperatures stay below 180°F and you need low friction at low cost.
Get a PEEK Part Quote in Minutes
Upload your CAD file. Select your PEEK grade. See your price instantly with lead time options.
Upload CAD for Instant QuoteIndustries That Use CNC Machined PEEK
PEEK shows up in the most demanding environments on the planet. Here are the top industries.
Semiconductor
Wafer handling components, wet bench fixtures, and chamber insulators in PEEK 450G. Resists all process chemicals. No particle generation. Dimensionally stable in clean rooms at elevated temperatures.
Aerospace & Defense
PEEK CF30 bushings replace bronze in flight controls. PEEK brackets save 50–80% weight over stainless 316. PEEK insulators handle engine bay temperatures that melt nylon and Delrin.
Medical Devices & Implants
PEEK-OPTIMA spinal fusion cages, dental implant abutments, and trauma fixation plates. ISO 10993 biocompatible. Radiolucent for clear X-ray and MRI imaging around the implant.
Oil & Gas
Downhole seals, valve seats, and backup rings in PEEK-HT. Handles 500°F+ downhole temperatures, H2S sour gas, and hydraulic fluid. Replaces metal seals that corrode and gall.
Chemical Processing
PEEK pump components, valve seats, and gaskets that resist hydrochloric acid, sodium hydroxide, and organic solvents. No corrosion. No contamination. Lasts 5–10x longer than stainless 316 in aggressive chemical environments.
Robotics & Automation
PEEK CF30 end effector components that handle high temperatures near welding and soldering stations. Self-lubricating bearings that run dry in clean environments. Lightweight brackets that reduce arm inertia.
Design Tips for CNC Machined PEEK Parts
PEEK machines well, but it is expensive. Smart design saves material and cuts cost.
1 Minimize Material Waste
PEEK stock costs $200–$800 per pound. Every chip you cut is money. Design parts close to the stock size. Avoid oversized billets that get machined down to small features. A part that starts from 1" round stock costs half as much as one that starts from 2" round stock.
2 Use PEEK Only Where You Need It
Do not make the entire assembly from PEEK. Use PEEK for the bushing, seal, or insulator that needs it. Make the housing from aluminum 6061 or stainless 304. A hybrid design with a $50 aluminum housing and a $100 PEEK insert beats a $400 all-PEEK part.
3 Consider Stress-Relief Annealing
PEEK builds internal stress during machining. For parts with tight tolerances (±0.001"), a stress-relief anneal between roughing and finishing passes keeps the part stable. This adds a day to lead time but prevents warping after machining.
4 Choose the Right Grade for the Job
Do not use PEEK CF30 when PEEK 450G will work. CF30 costs more and is harder on tooling. Use unfilled PEEK 450G for chemical resistance and biocompatibility. Use GF30 for dimensional stability. Save CF30 for maximum strength and metal replacement.
5 Keep Inside Corner Radii at 0.030"+
Same rule as any CNC material. End mills are round. A 0.030" inside corner radius costs nothing extra. Sharp corners need smaller tools and slower feeds, which increases cost — and with PEEK at $200+/lb, you want fast, efficient machining.
Finishes for PEEK Parts
PEEK has a natural tan/brown color. It machines to a good surface finish straight off the tool. Here are your options.
- As-machined: Clean tool marks, 32–63 Ra surface finish. This is what most PEEK parts get. Good enough for seals, bushings, and structural parts.
- Polished: Hand-polished to 16 Ra or better for sealing surfaces, medical implants, and optical components. Adds cost but gives a smooth, glossy finish.
- Tumbled / deburred: Removes sharp edges and burrs. Standard on all parts. Safe to handle.
- Plasma treated: Surface activation for bonding or coating adhesion. PEEK has low surface energy, so plasma treatment helps paint and adhesives stick.
- Laser engraved: Part numbers, lot codes, and UDI marks for medical device traceability. Clean, permanent marking.
Note: PEEK does not need corrosion protection, anodizing, or plating. Its natural chemical resistance means the as-machined surface is ready for service in nearly all environments.
Tolerances for CNC Machined PEEK
PEEK holds good tolerances, but filled grades hold them better. Here is what to expect.
- General features: ±0.003" (±0.076 mm)
- Precision features: ±0.001" (±0.025 mm)
- Surface finish: 32–63 Ra standard, 16 Ra achievable on polished surfaces
- Flatness: 0.002" per inch on machined surfaces
- Concentricity: 0.001" TIR on turned features
For the tightest tolerances, use PEEK CF30 or PEEK GF30. The fillers reduce thermal expansion and increase stiffness, which means less movement during and after machining. For critical parts, we recommend a stress-relief anneal cycle between roughing and finishing operations.
Need PEEK Parts for Your Next Project?
Upload your CAD file and see exact pricing. PEEK 450G, GF30, CF30, and PEEK-HT available. Free DFM review on every upload.
Upload CAD for Instant QuoteWhy RivCut for PEEK CNC Machining
PEEK is not a material you want to waste. Here is why teams trust RivCut with their PEEK parts.
- All four grades available. PEEK 450G, PEEK GF30, PEEK CF30, and PEEK-HT. We keep stock on hand so you do not wait for material orders.
- PEEK-specific tooling. We use carbide and diamond-coated end mills designed for PEEK. This gives clean cuts, tight tolerances, and no melting or delamination on filled grades.
- Material waste tracking. We log every gram of PEEK stock and finished weight. You know exactly where your expensive material goes. We optimize nesting and fixturing to minimize waste.
- Stress-relief annealing in-house. For tight-tolerance PEEK parts, we anneal between roughing and finishing. This keeps dimensions stable and prevents post-machining warping.
- Free DFM review. Our machinists check your PEEK design for material waste, thin walls, and tolerance issues before cutting starts. This often saves 20–30% on material cost.
- 100% made in USA. Every PEEK part is machined in our Union City, California facility. Full traceability. Material certs available.
The RivCut Guarantee
If your PEEK parts do not match your drawing, we remake them at no charge. Given PEEK material costs, we take extra care with every part. Double inspection on all PEEK orders. Every critical dimension is verified with calibrated equipment before shipping.
Related Tools & Articles
PEEK CNC Machining: Common Questions
Related Resources
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Get Your PEEK Part Quote in Minutes
Upload your CAD file for instant pricing. PEEK 450G, GF30, CF30, and PEEK-HT available. Rush delivery in as few as 3 business days. 100% made in USA.
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