PEEK (Polyetheretherketone) Overview
Polyetheretherketone, commonly referred to as PEEK, is part of the polyetherketone family of semicrystalline thermoplastics. Other semicrystalline materials with various ratios of ether to ketone in their structure include PEK, PEKK, PEKEKK, and PAEK. However, the PEEK polymer’s unique 2:1 ether (E) to ketone (K) ratio affords superior chemical resistance compared to other polyetherketones and is a major factor contributing to PEEK’s more widespread use.
Recognized for all-around high-performance, PEEK features an impressive list of physical properties. The semicrystalline thermoplastic also withstands long-term exposure to high pressure steam, hot water and many highly aggressive chemicals. Its wear resistance under dynamic load adds to the performance benefits behind PEEK specifications for injection-molded and machined components that must withstand severe service conditions.
PEEK Resin Suppliers, Products
Since the commercial introduction of PEEK in 1980, Victrex PLC has become its leading producer and supplies the ultra high-performance thermoplastic worldwide from its operations in the UK. The company’s application development efforts span more than 40 years and have led to the widespread use of PEEK for components in aerospace, oil and gas exploration and production, semiconductor manufacturing, medical and military and defense equipment.
With the proliferation of parts specified in Victrex® PEEK and engineers’ growing awareness of the material’s capabilities, new application possibilities emerged that were beyond the performance limits of the initial grades. These opportunities led to development of PEEK materials that serve a broader range of applications. Enhanced performance grades include formulations with improved bearing and wear properties and with glass and carbon fiber reinforcement that significantly increases PEEK’s structural strength.
Its relatively easy melt-processability also led to adaptations of PEEK resin for diverse processing methods including injection molding, compression molding, and extrusion of fibers, pipe, tubing, film and machinable stock shapes. Opening these processing alternatives further expanded PEEK’s range of applications and the industries in which the material is specified.
Solvay began production of PEEK resin in the U.S. in the early 2000s and also actively developed products for severe service applications in a range of industries. Commercialized under the designation KetaSpire® PEEK, Solvay’s family of grades includes formulations with performance enhancements for greater wear resistance and structural strength. The KetaSpire® PEEK product family is also typically melt-processed by extrusion and injection molding and serves numerous industries and applications in the form of molded parts, and extruded stock shapes that are machined into precision components, and extruded film and tube.
More recent developments in PEEK polymers by Victrex PLC and Solvay include biocompatible grades for human implantable and non-implantable life-sciences applications, as well as grades with higher temperature capabilities. Invibio Biomaterial Solutions, a Victrex company, designates their implant grade as PEEK-Optima™, and Solvay brands their implantable product Zeniva® PEEK.
PEEK Stock Shapes for Machining
Because of PEEK’s relative ease of processing, stock shapes made from a variety of grades of this ultra high-performance thermoplastic are readily available to machine shops worldwide. Drake supplies its full range of PEEK stock shapes to many of these machining companies who are well-qualified in the production of high-quality precision parts.
Drake’s PEEK Process Control and Fiber-Orientation Technology
Drake Plastics’ technology in PEEK shapes extrusion and injection molding focuses on tightly controlling the high temperatures and pressures involved in melt processing. Our expertise in this area ensures the maximum levels of properties and dimensional stability of PEEK machined and molded parts.
With glass and carbon fiber-reinforced PEEK grades, a significant factor in determining finished part performance in processing and machining involves the technology to manage fiber orientation. This is an area where Drake has decades of successful experience both in melt processing and in defining the ideal fiber orientation in machined parts to achieve maximum strength and dimensional stability for your application.
Drake’s PEEK Stock Shapes, Tradenames
Drake offers a complete family of PEEK stock shapes, from unreinforced and enhanced bearing and wear grades to glass and fiber-reinforced formulations in the industry’s widest range of sizes.
Depending on the specific grade of resin used, Drake Plastics applies the Victrex® PEEK or the Solvay KetaSpire® PEEK brands to its optimum quality extruded shapes. These premium shapes include those unique to Drake, such as 10-inch/ 255mm diameter rod and plate in 4.0-inch/ 200mm thickness, representing the largest extruded shape sizes available worldwide.
Drake also offers shapes branded as Drake Industrial Grade PEEK that are equivalent or somewhat higher in quality compared to other commercially available PEEK stock shapes. As is the case with competitive PEEK rod and plate, the products we designate as Drake Industrial Grade PEEK are supplied without resin certifications confirming Mil-P46183 compliance. They are extruded in high volumes under conditions that afford the economics required for certain applications.
PEEK Performance Profile
Strength retention and dimensional stability at elevated temperatures
PEEK ranks high on flexural and tensile strength at elevated temperatures. Its properties include a Tg (glass transition temperature) of 302°F (150°C). In unreinforced grades its heat deflection temperature measures 315°F (157°C), and fiber-reinforced grades maintain high strength at even higher temperatures. Victrex’ properties data lists the heat deflection temperature of its 30% carbon-fiber reinforced Victrex 450 CA30 PEEK, for example, at 520°F (271°C), a significant step up in performance over unreinforced formulations. It is important to note that this value is derived from samples molded with the fibers orientated optimally for testing. Actual injection molded parts or parts machined from stock shapes will not likely achieve this best possible result.
PEEK also exhibits exceptional resistance to creep or cold flow under load at high temperatures. It is also highly dimensionally stable when exposed to extreme temperature variations, with its low coefficient of linear thermal expansion.
Drake Plastics extrudes and injection molds several of the high strength glass and carbon fiber-reinforced PEEK formulations. Grades include Solvay’s 30% glass fiber-reinforced KetaSpire KT820 GF30 and 30% carbon fiber-reinforced KetaSpire KT 820CF30, and Victrex’ 30% carbon fiber-reinforced PEEK 450 CA30.
Although PEEK has high inherent wear resistance, enhanced bearing and wear grades of PEEK are available for applications exposed to severe levels of dynamic loading and speeds. One major advantage in machinery and production equipment is that moving parts made from these grades often do not need external lubrication. This can eliminate contamination from lubricants, a significant benefit for food, pharmaceutical and similar clean manufacturing operations. With their longer service life, parts made from wear-resistant PEEK grades can also lower maintenance costs and extend production run times between scheduled maintenance for part replacements.
Examples of bearing and wear-enhanced PEEK grades that Drake Plastics converts into stock shapes and parts include Victrex 450 FC30 “10-10-10” which incorporates PTFE, graphite and carbon fiber, and Victrex 450 FE20 PEEK containing 20% dispersed PTFE powder. Both grades are FDA compliant as well. Carbon fiber reinforced structural grades Victrex 450 CA30 & KetaSpire KT820 CF30 are optimal performers in some bearing applications, particularly those needing enhanced rigidity and strength. Key requirements for achieving the highest levels of performance include a wear counterface that is sufficiently hard and smooth in an assembly, and operating conditions where heat dissipation is adequate.
Chemical and hydrolysis resistance
Chemical resistance is one of the most notable attributes of PEEK. The high-performance thermoplastics’ unique 2:1 ratio of ether (E) to ketone (K) ratio imparts superior chemical resistance over other polyetherketones such as PEK, PAEK and PEKEKK. Its ability to withstand long-term exposure to a remarkably wide range of chemicals has led to many applications where it replaced metals for longer service life in aggressive environments such as downhole equipment in the oil and gas industry.
PEEK also withstands prolonged exposure to hot water, steam and radiation. Applications in food processing and pharmaceuticals production capitalize on this advantage with FDA compliant bearing grade PEEK for components that require thorough cleaning and sanitization between product runs.
The semiconductor manufacturing industry has specified various PEEK grades for tools and fixtures because of its inherent purity. This attribute minimizes ionic contamination during wet processes using various chemistries at high temperatures.
Its flammability ratings also make PEEK a frequent choice for electrical and aircraft components. Unreinforced PEEK carries a UL94 V-0 rating at 0.060″ and the fiber-reinforced grades are rated UL94 V-0 at 0.020″ thickness. PEEK also meets FAA flame and smoke generation standards for structural and electrical components in aircraft.
Typical PEEK Applications
Applications for the range of PEEK formulations are typically characterized by the need for the high-performance thermoplastic’s chemical and hydrolysis resistance, high strength up to its temperature limits, ionic purity, and wear resistance.
The oil and gas industry has recognized PEEK’s advantages for components used in downhole equipment where PEEK is specified for seals, valve seats, insulators, and electrical connectors. Industrial production equipment applications include bearing and wear machinery components and plasma welding tool tips. Chemical inertness and low ionic impurities are behind the choice of PEEK for tools and fixtures in semiconductor manufacturing process chemistries. Its low smoke generation, structural strength and thermal resistance are among PEEK’s performance benefits for aircraft components. FDA compliant bearing and wear and unmodified PEEK grades also serve a variety of food contact applications in processing and packaging equipment.
Application possibilities for PEEK continue to expand with the development of new classes of the ultra high-performance thermoplastic. High Temperature PEEK XT for example serves applications that had been beyond the thermal capabilities of traditional PEEK grades. In addition, Solvay and Victrex have expanded the uses of PEEK with their developments in biocompatible grades.
High Temperature PEEK
High Temperature PEEK, developed by Solvay and designated KetaSpire® PEEK XT, extends the thermal and mechanical properties and thus the application range of this exceptional high-performance thermoplastic. The material is a true PEEK. It has the same 2:1 ether (E) to ketone (K) ratio that gives the polymer inherently superior chemical resistance compared to other high temperature-resistant polyetherketones.
High Temperature KetaSpire PEEK XT resins available for injection molding and extrusion include an unreinforced grade and 30% glass and carbon fiber-reinforced formulations.
On thermal performance, PEEK XT’s glass transition temperature of 338°F (170° C) is 36°F (20°C) higher than traditional unreinforced PEEK. Its melting temperature is also higher by 81°F (45°C). High Temperature PEEK XT also retains its higher mechanical strength and excellent electrical properties at temperatures beyond the capabilities of traditional PEEK grades. Solvay reports that PEEK XT demonstrates a 400 percent higher tensile modulus and nearly 50 percent higher tensile strength at 320°F (160°C) over traditional PEEK. It also offers a major step-up in dielectric strength and volume resistivity for electrical applications exposed to higher temperature extremes.
Applications for the different grades of ultra high-performance PEEK XT take advantage of their greater strength retention at higher temperatures, electrical insulation and isolation and ablative properties compared to traditional PEEK.
Drake’s capabilities in High Temperature PEEK XT include injection molded parts and stock shapes for machining, as well as precision CNC-machined parts. All are based on Solvay’s unreinforced KetaSpire XT-920 NT, 30% carbon-fiber reinforced KetaSpire XT-920 CF30, and 30% glass-reinforced KetaSpire XT-920 GF30 PEEK.
Medical and Biocompatible PEEK Grades
PEEK offers several advantages over metals and other materials for medical and life science applications. The material’s inherent resistance to chemicals, gamma radiation and high-pressure steam adds long life to instruments and devices that require frequent autoclave cycles and sterilization. Light weight is an advantage for surgical and dental tools. The ability to injection mold PEEK also allows economical and exact reproducibility of tools and devices in high volume production. Several PEEK grades are available with the compliance and certification requirements for these and other medical industry applications.
Implantable PEEK grades including have also gained widespread acceptance in the medical field. They offer high strength as well as radio translucency, an advantage for visualizing implanted devices by various medical imagining methods.
Victrex developed a family of biocompatible grades under the PEEK-Optima™designation that have gained acceptance for components and devices for short-term and permanent human implant. These grades are stringently managed through invibio® Biomaterials Solutions, a Victrex company, and carry the PEEK-Optima™commercial designation.
Solvay also offers a portfolio of biocompatible PEEK grades for implantable and non-implantable applications. These materials carry the Zeniva® PEEK brand name and are available under rigidly-managed conditions to qualified companies in the medical industry.
Drake’s Product Development and Machining in Advanced PEEK Products
Process and product development in new materials like High Temperature PEEK XT is also a major focus at Drake. Our investments in this area provide engineers and specifiers access to new high-performance thermoplastics in a wide range of stock shape sizes and configurations for machined parts. Drake’s injection-molding capabilities are also available to seamlessly transition from machined to molded parts when volumes justify the investment in tooling.
Our rigid quality control systems and certifications have also positioned Drake as a capable and trusted partner for extruding, machining and molding components for medical and life science industry clients who supply us with Solvay’s implantable Zeniva® PEEK stock shapes and resins.