PEEK Plastic Machining

Your guide to PEEK Plastic Machining



Rigid opaque (beige) engineering plastic

Exceptional chemical, electrical and temperature resistence

Excellent mechanical properties maintained to high temperatures

PEEK (Polyaryletheretherketone) is a rigid opaque (beige) engineering plastic known for its ability to operate at high temperatures, together with its exceptional chemical and wear resistance and dimensional stability. It can be challenging to machine due to stress in the material and needs an experienced CNC machining partner.

This guide will take you through the main attributes, common applications, notes for designers and suitable finishing and treatments, as well as UK stock sizes and property tables. Don't forget to bookmark the page so you can refer back later.

If you are interested in PEEK machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

PEEK Guide: Properties, Applications and Design Considerations


What is PEEK?

PEEK (Polyaryletheretherketone) is a rigid opaque (beige) engineering plastic known for its ability to operate at high temperatures, together with its exceptional chemical and wear resistance and dimensional stability.

A high purity polymer, PEEK is a plastic composed of repeating monomers of two ether groups and a ketone group.

Although PEEK is very stable compared to most engineering plastics, stress in the material can have a major impact on machining causing such problems as: 

•    Warping and distortion
•    Reduced physical properties
•    Cracking
•    Changes in finished part dimension

This can be combatted by machining practices such as using very sharp tools, making sure we are using the right speeds and feeds, and being aware of how clamping/fixturing can affect the part. 

See the 'Finishing & Treatments' section for specific treatments to reduce the chances of stress affecting machining.

You may also see PEEK referred to as:

  • Tecapeek® (trade name)
  • Arlon® 1000
  • Ketronpeek
  • Victrex 450G
Industry Examples: Aerospace | Electronics | Military & defence | Medical | Chemical | Oil & gas | Food & packaging | Automotive
Typical Components & Applications: Valves | Seals | Connectors | Surgical instruments | Medical implants | Bearings | Bushings | Washers | Blocks | Insulation | Scraper blades

Main Attributes:
  • Impressive durability - exceptional chemical, electrical and temperature resistence
  • Excellent mechanical properties maintained to high temperatures
  • Dimensional stability
  • Very low moisture absorption
  • Flame retardant
  • High impact strength

Note For Designers:

PEEK is 53% harder than Acetal, has 63% greater tensile strength and is nearly 60% stiffer than Nylon 6. However, it is 10-20 times the price of other common engineering plastics. 

Here at Penta Precision, we are able to source PEEK competitively due to the high volume of PEEK components we manufacture; offering you the very best value for money. We use our PEEK machining experience to deliver the most cost effective method of manufacture.

When received as raw material, PEEK, similar to other engineering plastics will have a skin on both sides. When this skin is removed it is very common, especially on large billets with a lot of material being removed, for warping or distortion to occur, usually in the form of the material bowing inwards.

When quoting for a part of this nature, we would allow for the machinists to skim both layers of skin off, without taking the part to finish size, allowing it to warp and then re-machining both faces, thus heavily reducing the warping.

With low moisture absorption and being one of the most stable of plastics Penta can hold closer tolerances in PEEK than most other engineering plastics.

PEEK is available in several different grades; the choice of grade will depend on the application as seen below.

PEEK unfilled - Unfilled PEEK is an unreinforced general-purpose grade that offers steam and wear resistance. It provides the greatest elongation and toughness of all PEEK grades.

PEEK 30% Glass-Fiber Reinforced - The addition of glass fiber greatly reduces the expansion rate and increases the flexural modulus of PEEK. This grade is especially good for structural applications that require greater strength, stiffness, or stability

PEEK 30% Carbon-Fiber Reinforced - The addition of carbon fibre enhances the compressive strength and stiffness of PEEK, while dramatically lowering its expansion rate. It offers optimum wear-resistance and load-carrying capability in a PEEK-based product. This grade provides greater thermal conductivity than unreinforced PEEK, allowing for increased heat dissipation from bearing surfaces. The result is improved bearing life and capability.

PEEK Bearing grade - Carbon fiber reinforced with graphite and PTFE lubricants, bearing grade PEEK offers the lowest coefficient of friction and the best machinability of all PEEK grades.

Finishing & Treatments:

PEEK, much the same as other engineering plastics, has limited finishing/treatments. The main treatment being annealing or stress relieving. 

Annealing is a heat treatment that alters the physical and sometimes chemical properties of a material to increase its ductility and to make it more workable. Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties. When this process is done properly it can enhance the lifespan of machined plastic parts.

Stress Relieving consists of heating the steel to a temperature below the critical range to relieve the stresses resulting from cold working, shearing, or gas cutting. It is not intended to alter the micro-structure or mechanical properties significantly. Also, a process for making material softer. However, stress relieving does not change the material properties as does annealing.

Please contact us for more information on these processes or see our finishing processes page.

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Further Reading & Resources

British Plastics Federation


PEEK Plastic Machined Parts


Penta Precision provides the following plastic PEEK machining services: 
  • CNC milling
  • CNC turning
  • Prototypes and batch runs
  • Insert installation
  • Part marking
  • Manual milling
  • Manual turning
  • Machining design advice
  • Design for manufacture service

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