Material guide
PEEK, polyether ether ketone
PEEK, polyether ether ketone. The top of the engineering plastics pyramid, the material you reach for when everything else gives up. It takes high temperature, resists almost every chemical and carries load where ordinary engineering plastics soften. You pay for it, but for the right part there is nothing better.
What it is
PEEK stands for polyether ether ketone and is one of the highest performing thermoplastics there is. It is what is called a high-performance plastic, a step above the engineering plastics such as PA and POM. What makes PEEK special is the combination: high continuous service temperature, good mechanical strength even when it gets hot, good sliding properties and a chemical resistance that stands up to strong media. The material is turned and milled to tight tolerances and it holds its dimensions. This is not an everyday material you pick to save money, it is a material you pick when the requirements are so high that cheaper plastics drop out. The group comes in an unreinforced form and in filled grades, see the grades further down.
Properties
High continuous service temperature, handles heat where engineering plastics soften
Keeps its stiffness and strength even when the temperature rises
Good sliding properties and abrasion resistance, suited to bearings and sliding surfaces
Broad chemical resistance to acids, bases and solvents
Dimensionally stable and accurate, with low moisture absorption
Available in grades for purity and biocompatibility requirements
Common applications
PEEK sits where the environment is too tough for other plastics. Typical parts are bearings, plain bushings and sliding elements in hot or chemically aggressive machines, seals and valve components in process and pump industry, plus insulators and parts in electronics and semiconductor manufacturing. The material is also established in medical technology and in applications that call for autoclaving, since it takes repeated sterilization. When a designer has a part that has to take heat, chemicals and mechanical load all at once, the choice often lands on PEEK.
Limitations
The first limitation is the price. PEEK is expensive, so it should be chosen when the requirements genuinely justify it, not as a default. If your application tops out already at moderate temperature and chemical load, an engineering plastic such as PA or POM does the same job for a fraction of the cost. PEEK is not indestructible either: against certain strongly oxidizing media and concentrated acids even this material reaches its limit, and for extreme chemical resistance a fluoroplastic such as PTFE or PVDF can be a better choice. UV resistance is limited unless the grade is stabilized.
Our PEEK grades go to 260 °C in continuous service and 300 °C for short periods, and down to -40 °C. The material does not melt until around 341 °C.
Grades and variants
PEEK comes in an unreinforced form and in filled grades that are optimized for different requirements. The grades differ in stiffness, load-bearing capacity at temperature and which additives are involved.
Base grade
- PEEK unreinforced, the pure grade. Good all-round properties, good toughness and the natural choice when no special requirements apply. Typically supplied in a beige natural color.
Additives and reinforcements
- CF30, carbon fiber reinforced with 30% carbon fiber. Stiffer and more dimensionally stable, with higher load-bearing capacity at temperature. Common in bearings and structural parts.
- CF50, carbon fiber reinforced with 50% carbon fiber. Stiffer still and more dimensionally stable, for the most heavily loaded parts.
- GF30, glass fiber reinforced with 30% glass fiber. Higher stiffness and dimensional stability than the unreinforced grade, an option where electrical insulation has to be kept.
- Mod, bearing grade with glide and wear additives, optimized for low friction and high abrasion resistance in sliding surfaces and bearings.
- MG, medical grade for medical and food-related applications.
- HT, high temperature for an even higher continuous service temperature.
- LF, electrically conductive grade.
If you need a specific filled grade for a demanding part, get in touch and we will work out which one fits.
Machining
PEEK is turned, milled and drilled with sharp carbide tools, and it can be both welded and bonded. If the part has to hold tight tolerances, annealing before machining is almost always right, otherwise the material moves as the internal stresses release.
Formats we can supply
PEEK comes as sheets, round rods, tubes and hollow bars across a wide range of dimensions. You can see formats and dimensions in the range. Do you want a piece cut to size? Enter the dimensions in VisualCutter and you will see the price right away.