What is PEEK? A High-Performance Plastic for Demanding Applications
2025/11/7
What is PEEK?
PEEK (Polyether Ether Ketone) is a high-performance thermoplastic known for its exceptional mechanical strength, thermal stability, and chemical resistance. It maintains dimensional stability and durability even under high temperatures and harsh chemical exposure.
PEEK is widely used in aerospace, automotive, medical, and industrial applications where high reliability and long-term performance are critical.
Key Properties
PEEK is one of the highest-performing engineering plastics, commonly used in demanding industries such as aerospace and automotive.
It is often chosen as a metal substitute to reduce weight, improve performance, and lower costs. Components such as gears, washers, and bearings can be made from PEEK instead of metal, because it maintains strength, wear resistance, and chemical resistance even under high heat.
Heat Resistance
PEEK has outstanding heat and hydrolysis resistance compared to other high-performance plastics.
Continuous use temperature: up to 250°C
Withstands steam sterilization at 200–250°C
Short-term resistance up to 300°C
Resists thermal aging
However, because its glass transition temperature is 143°C, mechanical properties change significantly under heavy loads above ~150°C.
Mechanical Strength & Wear Properties
PEEK offers excellent tensile strength and impact resistance across a wide temperature range. Grades reinforced with glass or carbon fiber provide even higher strength.
Standard PEEK is not highly self-lubricating, but special bearing grades offer excellent wear performance, even in high-temperature, dry-running environments.
Flame Resistance
PEEK is naturally flame-resistant, producing very little smoke, corrosive gas, or toxic byproducts when exposed to fire or vacuum conditions.
Chemical & Electrical Resistance
PEEK is highly resistant to chemicals, especially acids and alkalis at high temperatures. However, it should not be used with strong solvents like concentrated sulfuric acid.
It also provides excellent electrical insulation and dielectric performance across a wide frequency range.
Food Contact Safety
PEEK meets both U.S. FDA requirements and Japanese Food Sanitation Law, ensuring safety for food-contact applications.
Radiation Resistance
Thanks to its stable chemical structure, PEEK resists degradation from radiation and electromagnetic exposure.
Grades of PEEK
PEEK is available in a variety of grades, allowing its versatile properties to be applied across many applications.
The sliding grade is filled with carbon fiber, graphite, and PTFE to reduce friction and improve wear resistance. It also dissipates heat effectively, making it reliable in environments up to 300°C. This grade works well for bearings, gears, and other moving parts where materials like POM or nylon may not hold up.
The glass fiber-reinforced grade (30% glass fiber) offers better dimensional stability, rigidity, and creep resistance than standard PEEK. It is suited for parts exposed to long-term static loads.
The carbon fiber-reinforced, conductive grade (30% carbon fiber) provides even greater rigidity than the glass fiber version, along with high strength, wear resistance, and creep resistance. Its thermal conductivity is about 3.5 times higher than standard PEEK, allowing heat to escape quickly. This makes it ideal for components that must resist static electricity or dust buildup.
Machining Considerations
PEEK is easy to machine and offers excellent dimensional stability. Depending on part geometry and machining details, we can achieve tolerances as tight as ±0.02 mm.
That said, because PEEK is extremely hard, it can chip during milling. When machining fine holes or using very small cutting tools, a higher risk of tool breakage. For these reasons, PEEK requires more careful machining than many other plastics.
Key Takeaways
PEEK is one of the highest-performing engineering plastics, with outstanding heat resistance, strength, dimensional stability, and chemical resistance. Its well-balanced properties make it suitable for a wide range of applications, including those where other materials may fall short.
However, because it is a premium material, cost and potential overengineering should be considered.
Step Up Your Project with Yumoto Electric
Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of engineering plastics, including PEEK, PPS, MC Nylon, and POM.
If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.
