PEEK vs PTFE: High-Performance Plastics for CNC Machining

When considering PEEK vs PTFE for CNC machining, PEEK is the better choice in applications involving high stress, elevated temperatures, or heavy loads. On the other hand, PTFE excels when low friction, excellent chemical resistance, or a non-stick surface is required. PEEK is commonly used in aerospace, automotive, and medical devices due to its strength, lightweight nature, and long-lasting durability. PTFE remains popular in environments where chemical inertness and smooth surfaces are critical. The table below highlights the demand and performance characteristics of these two plastics:

Choosing between PEEK vs PTFE is essential to ensure CNC machined parts perform optimally and have a longer service life.

Material Overview

PEEK Properties

PEEK is a strong thermoplastic. Engineers like PEEK because it is tough and stable. It works well when there is a lot of stress or heat. PEEK is used for hard CNC machining jobs. It keeps its shape and strength up to 260°C. PEEK does not wear out fast. It stays strong even with heavy loads.

Here are some facts about PEEK’s mechanical and thermal properties:

PEEK also stands up to many chemicals. It can handle acids and hydrocarbons. Makers can add glass or carbon fibers to PEEK. This makes it even stronger and harder to wear out. PEEK is lighter than metal but still very strong. It is easy to machine into tricky shapes with special tools. That is why PEEK is used in aerospace, cars, and medical parts.

PTFE Properties

PTFE is known for being very slippery. It is great when you need low friction and chemical safety. PTFE has a very low friction number, as low as 0.05. It does not react with most chemicals, even strong ones. PTFE stays stable from -200°C to +260°C.

Some important PTFE properties are:

• Low friction: Parts move smoothly and do not wear out fast.

• Chemical inertness: PTFE does not react with most chemicals.

• Temperature stability: It works in very hot or cold places.

• Moderate wear resistance: PTFE is soft and can bend under heavy weight.

PTFE is used for seals, gaskets, and non-stick coatings. In food factories, PTFE coatings make cleaning much easier. Cleaning can be over 90% faster. In chemical plants, PTFE parts stop rust and damage by more than 80%. PTFE’s low friction and chemical safety help it work well in many factories.

PEEK vs PTFE Comparison

Comparison Table

This table shows the main properties of both materials. It helps engineers and designers pick the right one for their project. You can see which material is better for each property.

Tip: Use this table to quickly compare PEEK vs PTFE for CNC machining.

Strengths & Weaknesses

PEEK and PTFE both have good points and bad points. Knowing these helps you pick the best one for your CNC machining job.

PEEK Strengths

• PEEK is strong and stiff, so it works well for parts that hold weight.

• It does not get tired or change shape easily over time.

• PEEK keeps its shape and works well even at 250°C.

• It is easy to machine into detailed shapes.

• PEEK does not change size much with heat, so it stays the right shape.

• It resists most acids and hydrocarbons.

PEEK Weaknesses

• PEEK has more friction than PTFE, so it can wear out faster when sliding.

• Pure PEEK coatings do not work well in places with lots of rubbing unless fillers are added.

• PEEK costs a lot, so it is not good for cheap projects.

• Strong acids like sulfuric acid can damage PEEK.

PTFE Strengths

• PTFE is very slippery, so things do not stick to it and it slides easily.

• It does not react with almost any chemical.

• PTFE can stretch a lot without breaking.

• It is great for electrical insulation because it handles high voltage.

• PTFE costs less than PEEK, so it is used in more places.

PTFE Weaknesses

• PTFE is not as strong as PEEK when pulled or pressed.

• It is soft and can change shape under heavy weight.

• PTFE wears out faster if used with rough or heavy loads.

• It changes size more with heat, so it is less stable.

• If you mix more PTFE into blends, it gets weaker except for impact strength.

Note: Mixing PTFE with PEEK can make parts slide better and last longer, but they may not be as strong.

When you look at PEEK vs PTFE, think about what your CNC part needs. PEEK is best for tough, hot, or very exact jobs. PTFE is better when you need low friction, chemical safety, or electrical insulation.

Mechanical Performance

Strength & Stiffness

PEEK and PTFE act very differently when tested for strength and stiffness. PEEK is one of the strongest plastics used in CNC machining. It keeps its shape under heavy weight and does not bend much. PTFE is much softer and stretches more when pulled.

• PEEK stays strong even at high temperatures, up to 260°C. This makes it a good pick for aerospace and car parts that face heat and stress.

• PTFE is good for bearings and seals because it is light and slippery. But it wears out fast unless mixed with fillers like glass fiber or bronze. These fillers help PTFE bend less and carry more weight.

A table below shows how they compare:

Short fibers in PEEK make it even stronger and stiffer. Carbon and glass fibers help PEEK work well in tough jobs where parts hold a lot of weight.

Note: CNC machining shapes PEEK and PTFE very accurately. This keeps their strength and lets parts fit together tightly.

Wear Resistance

Wear resistance is important for moving parts. PEEK lasts a long time, even with lots of rubbing and movement. PTFE is very slippery but wears out faster unless changed.

Tests over time show:

PEEK/PTFE mixes have the best of both. They are slippery and last a long time, so they are great for parts that need to keep working. Tiny particles can make PEEK even tougher by making a shield during use.

Engineers pick PEEK for gears, bushings, and strong parts that must last. PTFE is best for jobs with little weight and where things need to slide easily.

Thermal Performance

Temperature Limits

PEEK and PTFE both work well in hot places, but they have different limits. Engineers use tests to see how plastics act when heated. These tests include Maximum Service Temperature and Continuous Use Temperature. They also use Relative Thermal Index (RTI). These tests help show the highest heat a material can take and still keep its strength and electrical abilities.

PEEK is a high-temperature plastic. It can work all the time at up to 249°C (480°F). This makes PEEK a good pick for parts that get hot a lot, like in airplane engines or car transmissions. PTFE is called an extreme temperature plastic. It can handle heat above 300°C, but the exact number depends on the test and use. PTFE’s heat resistance makes it great for seals and gaskets in chemical plants.

Note: Both PEEK and PTFE keep their properties when hot, but PEEK stays stronger when heated.

Thermal Stability

Thermal stability means how well a material keeps its shape and strength when the temperature changes. Scientists use tests like modulated differential scanning calorimetry (MDSC) and thermal cycling to check this.

• Researchers tested PEEK and PTFE up to 225°C. They saw that PEEK keeps its shape and strength better than PTFE when heated and cooled.

• Microstructural studies, like X-ray diffraction and scanning electron microscopy, show PEEK’s structure stays stable after many heating cycles.

• PTFE loses some strength after lots of heating and cooling, but PEEK can get better because stress from machining goes away.

• Adding carbon fibers or graphite to PEEK or PTFE helps them spread heat and makes them more stable.

• Both materials did not change much in size or weight after many heating and cooling cycles.

PEEK’s great thermal stability makes it perfect for CNC machined parts that get hot and cool down many times. PTFE works well in places that stay hot, but it may lose strength if the temperature changes a lot.

Chemical Resistance

Fluid & Gas Compatibility

PEEK and PTFE both do not get damaged by many chemicals. This makes them good for jobs with strong fluids and gases. The Atlas Fibre guide says PEEK can handle many acids, bases, and solvents. For example, PEEK works well with acetic acid, hydrochloric acid, and hydrogen peroxide up to 30%. But it does not do well with sulfuric acid above 10%, chlorine water, or some solvents like methylene chloride. PTFE stays safe with almost all chemicals because of its strong carbon-fluorine bonds.

The Cole-Parmer Chemical Compatibility Database helps engineers see how PEEK and PTFE react with different chemicals. This tool checks what happens after 48 hours with acids, solvents, and gases. It also reminds people that heat, pressure, and how much chemical is used can change the results.

Tip: PTFE is best for places with very strong chemicals or when you do not know what chemicals will be used.

Tests show that both PEEK and PTFE work well in places with a lot of hydrogen. Low hydrogen helps them last longer, but too much hydrogen can make them wear out faster.

Inertness

PTFE is special because it does not react with most chemicals. Even in tough places, PTFE keeps its shape and does not break down. This is because of its strong carbon-fluorine bonds. PTFE is great for seals, gaskets, and linings in harsh chemical places.

PEEK is also very stable with chemicals and heat, especially when mixed with fillers like graphite or carbon nanotubes. These fillers help PEEK last longer and keep its shape. Studies show PEEK stays strong in hydrogen and vacuum places. PEEK does not let germs grow on it, which helps it stay clean.

Research shows PEEK/PTFE mixes keep low friction and stay stable even in very cold places. Thin films form on surfaces and help both materials keep their inertness during use.

PEEK and PTFE both have great chemical resistance and inertness, but PTFE is still the best for the hardest chemical jobs.

Machinability

CNC Processing

PEEK and PTFE are both tricky to machine. PEEK gets very hot when cut, so workers must watch the heat. They change the cutting speed and feed rate to keep things cool. Coolant is used to stop parts from getting too hot or growing bigger. Picking the right tool is important. The tool’s material and coating help lower friction and stop wear. This keeps the part strong and in good shape. PEEK is tough, so it can be made into detailed and exact parts. Its strength and chemical safety make it great for planes, medical tools, and machines.

PTFE is much softer and bends more easily. Workers need very sharp tools and must slow down the feed rate. This stops PTFE from bending out of shape. Even though PTFE melts at high heat, cooling is still needed. Cooling stops the part from warping. PTFE can shake or bend while being turned. Clamping it gently helps avoid marks and saves material. Turning, milling, and drilling all work for PTFE. But bigger tool tips and cutters with many edges are better. These tools lower the stress when cutting. PTFE’s chemical safety and ability to block electricity also change how it is machined.

Tip: Always use machining methods that fit the material’s properties for the best results.

Surface Finish

Getting a smooth finish on PEEK or PTFE needs special steps. Workers use very sharp tools made from high-speed steel or carbide. The tool’s edge is polished to cut better. A rake angle between 0° and 15° helps stop friction and bending. Cutting speeds from 200 to 500 m/min are used. Feed rates are kept low, about 0.1–0.2 mm/rev, to stop heat and tearing. Shallow cuts, from 0.5 to 1.5 mm, lower stress and keep the part from bending.

Workers often blow away chips with air or use light water-based coolants. This keeps the part cool and clean. Parts are clamped tightly but not too hard. This stops shaking and keeps the part from changing shape. The room should stay around 20–25°C. This stops the part from getting bigger or smaller from heat. After cutting, polishing with fine abrasives or diamond paste makes the surface smooth. Soft pads are used so the part does not get too hot.

Paying close attention to these steps helps PEEK and PTFE parts meet strict rules for smoothness and size.

Cost Factors

Material Price

PEEK is one of the priciest plastics for CNC machining. Its high cost comes from its special features and how hard it is to make. Regular PEEK without fillers costs about $75 to $120 for each pound. If glass or carbon fiber is added, the price can go up to $180 per pound. Medical and implant-grade PEEK needs to be very pure and safe, so it often costs more than $150 per pound. Other plastics like PEI (Ultem) and PPS are much cheaper. Sometimes, they cost only a quarter or even a tenth of what PEEK costs.

PTFE is not shown in the same table, but it usually costs less than PEEK. Makers sometimes add PTFE to PEEK to help parts slide better. Because PEEK is so expensive, it is important to pick it only when needed for the job.

PEEK costs more because it is strong, handles heat, and resists chemicals.

Production Value

PEEK’s high price can be worth it for tough jobs. Its great strength, chemical safety, and heat resistance help machines last longer. Companies that use PEEK in planes, cars, or medical tools need to replace parts less often. This means less time fixing things. PEEK needs special machines and higher heat to make, but its toughness makes up for these extra steps.

PTFE works best when you need things to slide easily or not react with chemicals. It is often mixed into PEEK to help parts last longer. PTFE is cheaper and easier to use, but it is not as strong or reliable as PEEK for hard jobs.

Picking PEEK is smart when you want parts to last a long time and work well, even if it costs more at first. PTFE is a good choice for easier jobs or to help other materials work better.

Applications

PEEK Uses

PEEK is used in jobs that need strong and heat-safe parts. It is picked for airplane cabins because it is light and does not change with heat. This helps planes use less fuel and stay safe. Doctors use PEEK to make tools and spine implants. PEEK is safe for the body and acts like bone, so it works well in surgeries. Car makers use PEEK for engine parts and wires. These parts last long because PEEK does not wear out fast or melt easily.

• Aerospace: Light cabin parts, brackets, and panels for insulation.

• Medical: Spinal cages, dental posts, and tools for surgery.

• Automotive: Gears, piston rings, and covers for wires.

Tests show PEEK bars fit better than metal ones after many uses. PEEK can take hits and shocks, so it keeps devices and people safe. Dentists use PEEK for custom posts and cores. This saves time and stops breaks. In factories, PEEK mixed with carbon fiber is strong for hard jobs like threading. This mix lets companies make thick parts without breaking them.

PEEK is strong, easy to shape, and stays the same, so it is great for CNC parts that must work well.

PTFE Uses

PTFE is best where things must slide easily and not stick. It is used in planes for seals and gaskets in fuel and air systems. These parts can handle hot and high-pressure places. PTFE is also used for fuel lines and valves in planes. It keeps them safe with all kinds of fuels. Electric workers use PTFE to cover wires because it blocks electricity well.

• Aerospace: Seals, gaskets, wire covers, and valve parts.

• Oil and Gas: Liners for pipes and tanks that stop rust.

• Food and Beverage: Non-stick liners and surfaces that are safe to use.

• Pharmaceuticals: Clean, safe parts that do not react with chemicals.

• Mining and Metal Processing: Liners that help things slide and stop rust.

New PTFE liners can bend and work better in tough places. More companies use PTFE because it is safe, lasts long, and does not let things stick or react.

PTFE is useful and tough, so it is needed for CNC parts in chemical and food factories.

PEEK vs PTFE: How to Choose

Selection Guide

Picking the right material for CNC machining is very important. Engineers and designers need to match the material’s features to what the part needs. Here is a simple guide to help teams pick between PEEK and PTFE for their next CNC part:

1. Evaluate Material Properties
   Look at how strong, tough, and heat-safe each plastic is. PEEK is very strong and can handle high heat. PTFE is great because it does not react with chemicals and is very slippery.

2. Understand Application Needs
   Think about what kinds of stress the part will face. If the part will hold heavy weight, get hit a lot, or get very hot, PEEK is a good choice. If the part will be around strong chemicals or needs to be non-stick, PTFE is better.

3. Consider Machinability
   See how each material acts when being cut by CNC machines. PEEK is easy to shape into small, detailed parts. PTFE is soft, so it needs careful cutting, but it can be made very smooth.

4. Balance Cost and Performance
   Check how much money you can spend and what you need the part to do. PEEK costs more but lasts longer in hard jobs. PTFE is cheaper and works well if you need chemical safety or low friction.

5. Inspect Compatibility with Secondary Processes
   Make sure the material will work with any extra steps like finishing or putting parts together. Both PEEK and PTFE might need special surface work.

6. Check Supplier Reliability and Material Availability
   Make sure your supplier can always give you good quality and deliver on time. This helps avoid delays and keeps your parts the same every time.

7. Prototype and Test
   Make a sample part and test it in real life. This helps you know if you picked the right material before making lots of parts.

Tip: Ask material experts or skilled CNC machinists for advice. They can help you make the best choice, especially for tricky or important projects.

Key Questions

Before you pick PEEK or PTFE, teams should answer these important questions:

• What kinds of forces will the part face, like pulling, pushing, hitting, or bending?

• Will the part get very hot or go through lots of temperature changes?

• Does the part need to resist certain chemicals or solvents?

• Does the part need to be slippery or non-stick?

• Is it important for the part to keep its shape and size exactly?

• How much money can you spend on the material and making the part?

• Are there any rules or standards the material must meet?

• Can the supplier always give you good quality and deliver on time?

• Will the part need extra steps like gluing, coating, or putting together?

• Has the team tested sample parts in real working conditions?

Answering these questions helps engineers and designers make smart choices. This makes sure the CNC part works well and fits the budget.

PEEK and PTFE are two plastics that engineers pick for different jobs. PEEK is very strong and keeps its shape well in heat. This makes it good for airplane and medical parts. PTFE does not react with most chemicals and is very slippery. That is why it works well for seals and gaskets.

• Pick the plastic that fits your project best.

• Use PEEK if your part needs to be strong or very exact.

• Use PTFE if you need chemical safety or a slippery surface.

If your project is hard or very important, ask a material expert for help.

FAQ

What makes PEEK better than PTFE for high-stress parts?

PEEK offers much higher strength and stiffness than PTFE. Engineers choose PEEK for parts that must handle heavy loads or high temperatures. PTFE works best for low-friction or chemical-resistant needs.

Can PTFE and PEEK be used together in one component?

Yes. Manufacturers often blend PTFE with PEEK to combine low friction with high strength. This mix creates parts that last longer and slide smoothly in demanding environments.

Is PEEK safe for medical implants?

PEEK is biocompatible and resists body fluids. Doctors use it for spinal cages, dental posts, and surgical tools. Medical-grade PEEK meets strict safety standards for implants.

Does PTFE work well for electrical insulation?

PTFE insulates against electricity very well. Electricians use PTFE for wire coatings and insulators in high-voltage equipment. Its chemical resistance adds extra protection.

How does cost affect the choice between PEEK and PTFE?

PEEK costs more than PTFE. Teams pick PEEK when they need top strength and heat resistance. PTFE fits projects that need chemical safety or low friction at a lower price.