Take a 'peek': An insight into PEEK

PEEK, the commonly used abbreviation for PolyEtherEtherKetone, is a semi-crystalline engineering thermoplastic. It is considered to be fairly advanced compared to other engineering plastics due to its very high maximum allowable service temperature in air. Its unique combination of high mechanical properties, temperature resistance and excellent chemical resistance make it the most popular advanced plastic material on the market.

Material Characteristics

PEEK has a unique combination of properties, making it a very popular choice for an advanced engineering plastic. Characteristics of PEEK include:

• Very high maximum allowable service temperature in air (250°C continuously, up to 310°C for short periods of time)
• High mechanical strength, stiffness and creep resistance, also at elevated temperatures
• Excellent chemical and Hydrolosis resistance
• Excellent wear and frictional behaviour
• Very good dimensional stability
• Excellent resistance to high energy radiation (gamma and x-rays)
• Inherent low flammability and very little smoke evolution during combustion

Markets Served and Typical Applications

As PEEK is classified as an advanced engineering plastic, (due to its very high maximum allowable service temperature), it can be used in more extreme applications than general engineering plastics. It has applications in: aerospace, medical and food and beverage industries.

Aerospace

PEEK is utilized in the aerospace industry, in both commercial and military aircraft applications. It has several proven valuable properties that make it an ideal material for aircraft applications. One of these is PEEK’s weight, as even a couple of grams can make a huge difference in aerospace applications and weight can negatively impact fuel cost, so the lightweight of PEEK is a huge advantage. Additionally, PEEK has excellent thermal resistance, low smoke generation and is so resistant to heat and fire that it can self-extinguish. Applications range from exterior fittings such as landing gear hubcaps and thermal isolators and fasteners to interior fittings such as door handles and cabin lighting.

Medical

PEEK is often used in the medical industry due to its biocompatibility. As many polymers are rejected by the human body’s immune system, which can result in life-threatening situations, the medical industry is constantly searching for materials that are compatible for use in the human body. Even if a material is accepted, there is a risk that pieces of the material could splinter and interfere with biological function due to abrasive wear and intense friction. This is where PEEK’s excellent wear resistance, strength and modulus that approximates human bone, alongside its inertness and biocompatibility, make it suitable for use in the medical industry. Applications it has been used in include: spinal implants, dental implants and skull reconstruction.

Food and Beverage

Unfilled grades of PEEK are suitable for use in food and beverage production and packaging applications, where stringent regulations apply. The composition of the raw materials used for the manufacture of Ketron 1000 PEEK stock shapes complies with the regulations of the European Union (Directive 2002/72/EC, as amended) and the United States of America (FDA) for plastic materials and articles intended to come into contact with foodstuffs. Typical application for PEEK include: mixing paddles, filling nozzles, bushing, bearings and valve components. PEEK is especially useful for use in citrus fruit processing and hot filling machines due to its excellent operating temperature and chemical resistance.

This is only a small example of the types of industry and applications that PEEK is used in, as PEEK is the most available and versatile advanced engineering plastic on the market.

Grades of PEEK

In addition to their unfilled grade of PEEK (Ketron® 1000 PEEK), Quadrant EPP does a range of different grades of PEEK with varying properties.

Ketron® GF30 PEEK (30% glass reinforced)

This 30% glass fibre reinforced grade (colour: brownish-grey) offers a higher stiffness and creep resistance than Ketron 1000 PEEK and has a much better dimensional stability. This grade is very appropriate for structural applications carrying high static loads for long periods of time at elevated temperatures. The suitability of Ketron GF30 PEEK for sliding parts, however, is to be carefully examined since the glass fibres tend to abrade the mating surface.

Ketron® CA30 PEEK (30% carbon fibre reinforced)

 This 30% carbon fibre reinforced grade (colour: black) combines even higher stiffness, mechanical strength and creep resistance than Ketron GF30 PEEK with an optimum wear resistance. Moreover, compared to unreinforced PEEK, the carbon fibres considerably reduce thermal expansion and provide 3.5 times higher thermal conductivity - dissipating heat from the bearing surface faster, improving bearing life and pressure-velocity capabilities.

Ketron® LSG PEEK (life science grade)

 Ketron LSG PEEK stock shapes (colours: natural, black) are produced from selected batches of PEEK polyetheretherketone resin. This material exhibits a unique combination of mechanical properties, temperature and chemical resistance. The composition of the resin used for the production of the Ketron LSG PEEK stock shapes complies with the regulations that apply in the Member States of the European Union (Directive 2002/72/EC, as amended) and in the United States of America (FDA) for plastic materials and articles intended to come into contact with foodstuffs.  

Ketron LSG PEEK stock shapes have also been successfully type tested for their compliance with both United States Pharmacopeia (USP) and ISO 10993-1 guideline requirements for Biocompatibility Testing of Materials, and they come with full traceability from resin to stock shape. These features, added to an excellent sterilizability by means of steam, dry heat, ethylene oxide, plasma and gamma irradiation, make Ketron LSG PEEK stock shapes very suitable for applications in the medical, pharmaceutical and biotechnology markets.

Ketron® TX PEEK

This member of the Ketron PEEK family (colour: blue) has been developed especially for the food industry. Like Ketron 1000 PEEK, this new internally lubricated material has a food contact compliant composition, but offers far superior wear and frictional performance, making it expecially suitable for a wide variety of bearing and wear applications in the 100 to 200°C service temperature range.

Ketron® MD PEEK

The new PEEK metal detectable material is best suited for applications where high line speeds require good wear resistance, or where operating temperatures in use are higher than 130 °C. 

Ketron® PEEK is a registered trademark of the Quadrant group of companies.