PEEK Plastic Machining

Your guide to PEEK Plastic Machining

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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

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What is PEEK?

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.

Can we meet your PEEK plastic machining needs? Contact us now

UK Stock Sizes

PEEK UK Stock Sizes

Here are the standard stock sizes/colours for PEEK Tube, Round Bar and Plate in the UK. Please note we do not supply stock material, the information provided is purely for design and research purposes.

Stock sizes have a +/+ tolerance as the extrusion process is not as accurate as precision machining.

Stock finishes are often scratched and dented. Some sheet plastics come with a protective coating however because of long supply chains these can still be scratched underneath.

Example PEEK Stock Sizes

Stock sizes will vary depending on supplier. Please get in contact to discuss further.

PEEK Tube

Outside Diameter (mm)	Tolerance (mm)	Inside Diameter (mm)	Tolerance (mm)
50	+0.50/+2.20	30	-0.50/-2.20
50	+0.50/+2.20	40	-0.50/-2.20
60	+0.60/+2.80	30	-0.60/-2.80
60	+0.60/+2.80	40	-0.60/-2.80
60	+0.60/+2.80	50	-0.60/-2.80
70	+0.60/+3.40	30	-0.60/-3.40
70	+0.60/+3.40	40	-0.60/-3.40
70	+0.60/+3.40	50	-0.60/-3.40
70	+0.60/+3.40	60	-0.60/-3.40
80	+0.60/+3.40	40	-0.60/-3.40
80	+0.60/+3.40	50	-0.60/-3.40
80	+0.60/+3.40	60	-0.60/-3.40
90	+1.00/+4.00	40	-1.40/-5.40
90	+1.00/+4.00	50	-1.40/-5.40
90	+1.00/+4.00	60	-1.40/-5.40
90	+1.00/+4.00	70	-1.40/-5.40
100	+1.00/+4.00	40	-1.40/-5.40
100	+1.00/+4.00	50	-1.40/-5.40
100	+1.00/+4.00	60	-1.40/-5.40
100	+1.00/+4.00	70	-1.40/-5.40
100	+1.00/+4.00	80	-1.40/-5.40
115	+1.30/+5.00	50	-1.80/-7.00
115	+1.30/+5.00	60	-1.80/-7.00
115	+1.30/+5.00	70	-1.80/-7.00
115	+1.30/+5.00	80	-1.80/-7.00
115	+1.30/+5.00	90	-1.80/-7.00
115	+1.30/+5.00	100	-1.80/-7.00
125	+1.30/+5.00	50	-1.80/-7.00
125	+1.30/+5.00	60	-1.80/-7.00
125	+1.30/+5.00	70	-1.80/-7.00
125	+1.30/+5.00	80	-1.80/-7.00
125	+1.30/+5.00	90	-1.80/-7.00
125	+1.30/+5.00	100	-1.80/-7.00
140	+1.30/+5.00	50	+1.80/+7.00
140	+1.30/+5.00	60	+1.80/+7.00
140	+1.30/+5.00	70	+1.80/+7.00
140	+1.30/+5.00	80	+1.80/+7.00
140	+1.30/+5.00	90	+1.80/+7.00
140	+1.30/+5.00	100	+1.80/+7.00

PEEK Round Bar

Available in Natural (Beige) and Black

Diameter (mm)	Tolerance (mm)
Ø3-4	+0.10/+0.30
Ø5-6	+0.10/+0.40
Ø7-10	+0.10/+0.50
Ø11-20	+0.20/+0.90
Ø22-32	+0.20/+1.20
Ø35-40	+0.20/+1.60
Ø45-56	+0.30/+2.00
Ø60-70	+0.30/+2.50
Ø75-80	+0.40/+3.00
Ø90	+0.50/+3.40
Ø100	+0.60/+3.80
Ø110	+0.70/+4.20
Ø120	+0.80/+4.60
Ø130-140	+0.90/+5.40
Ø150-200	+1.00/+5.80
Ø165-180	+1.20/+5.00
Ø200	+1.30/+5.50
Ø210	+1.30/+5.80
Ø230-250	+1.50/+6.20

Round bar stock lengths may vary between 2,000m and 3,000 mm

PEEK Plate

Available in Natural (Beige) and Black

Size (mm)	Tolerance (mm)
5-6	+0.20/+0.70
8-10	+0.20/+0.90
12-25	+0.30/+1.50
30-50	+0.50/+2.50
55-70	+0.50/+3.50
80-100	+0.50/+5.00

Plate stock lengths may vary between 2,000mm and 3,000mm

Please note: some sizes may be non-stocked items and subject to minimum order quantities.

Technical Properties

PEEK Plastic Properties

PEEK Mechanical Properties

Properties	Value	Parameter	Norm	Comments
Modulus of Elasticity (Tensile strength) (MPa)	4200	1mm/min	DIN EN ISO 527-2	For tensile test: specimen type 1b
Tensile Strength (MPa)	116	50mm/min	DIN EN ISO 527-2
Tensile Strength at Yield (MPa)	116	50mm/min	DIN EN ISO 527-2
Elongation at Yield (%)	116	50mm/min	DIN EN ISO 527-2
Elongation at Break (%)	15	50mm/min	DIN EN ISO 527-2
Flexural Strength (MPa)	175	2mm/min, 10N	DIN EN ISO 178	For flexural test: support span 64mm, norm specimen.
Modulus of Elasticity (Flexural test)	4200	2mm/min, 10N	DIN EN ISO 178
Compression Strength (MPa)	23/43	1% / 2%, 5mm/min, 10N	EN ISO 604	Specimen 10x10x10mm
Compression Modulus (MPa)	3400	5mm/min, 10N	EN ISO 604	Specimen 10x10x50mm, modulus range between 0.5 and 1% compression
Impact Strength (Charpy) (KJ/m^2)	n.b.	Max 7,5J	DIN EN ISO 179-1eU	For charpy test: support span 64mm, norm specimen. nb = not broken
Notched impact strength (Charpy) (KJ/m^2)	4	Max 7,5J	DIN EN ISO 179-1eA
Ball indentation hardness (MPa)	253	-	ISO 2039-1	Specimen 4mm thickness

PEEK Thermal Properties

Thermal Properties	Value	Parameter	Norm	Comments
Glass Transition Temperature (°C)	150	-	DIN 53765	Found in public sources
Melting Temperature (°C)	341	-	DIN 53765
Service Temperature (Short Term) (°C)	300	-	-	Found in public sources. Individual testing regarding application conditions is mandatory
Service Temperature (Long Term) (°C)	260	-	-
Heat Distortion Temperature	162	HDT, Method A
Thermal Expansion (CLTE) (10-5 K-1)	5	23-60°C, long	DIN EN ISO 11359-1;2
Thermal Expansion (CLTE) (10-5 K-1)	5	23-100°C, long	DIN EN ISO 11359-1;2
Thermal Expansion (CLTE) (10-5 K-1)	7	100-150°C, long	DIN EN ISO 11359-1;2
Specific Heat (J/g*K)	1.1	-	ISO 22007-4:2008
Thermal Conductivity W/(K*m)	0.27	-	ISO 22007-4:2008

PEEK Electrical Properties

Electrical Properties	Value	Parameter	Norm	Comments
Specific volume resistance (Ω*cm)	1015	Silver electrode, 23°C	DIN IEC 60093	Specimen in 20mm thickness
Specific surface resistance (Ω)	1015	Silver electrode, 23°C, 12% R.H.	DIN IEC 60093
Dielectric Strength (Kv/mm)	73	23°C, 50% R.H.	ISO 60243-1	Specimen in 1mm thickness
Resistance to Tracking (CTI) (V)	125	Platin Electrode 23°C 50% R.H., solvent A	DIN EN 60112

Other PEEK Properties

Property	Value	Parameter	Norm	Comments
Water Absorption (%)	0.02/0.03	24h/96h (23°C)	DIN EN ISO 62	Øca, 50mm, h=13mm
Flammability	V0	Listed (Value at 1.50mm)	DIN IEC 60695-11-10

FAQs

Frequently Asked Questions About PEEK

What kind of plastic is PEEK?

PEEK is a high performance, high temperature semi-crystalline thermoplastic

Can PEEK be machined?

In short, yes, PEEK can be machined. Generally speaking PEEK has good machinability as long as it's in the hands of an experienced machinist.

Why is PEEK so expensive?

It sometimes comes as a surprise that PEEK is more expensive than other polymers. However, other engineering plastics are no match for PEEK when it comes to its strength, stiffness and temperature resistance so you really do get what you pay for. The good news is that at Penta we machine a lot of PEEK so are able to source at competitive prices.

Is PEEK recyclable?

Yes PEEK is recyclable.

Is PEEK plastic food grade?

Yes the standard grade of PEEK is a food safe plastic.

What is PEEK used for?

Because PEEK has superior qualities to most other thermoplastics and a higher price tag, it should really be used where these exceptional qualities are required for the application such as the aerospace industry. See the 'applications' tab for more information on typical components, applications and industries in which it is commonly used.

How strong is PEEK?

PEEK is an exceptionally strong engineering plastic with a tensile strength of 116 MPa - compared to 79 MPa for Nylon and 67 for Acetal.

What colour is PEEK?

Natural PEEK is a beige colour. It can also be obtained in various other grades and colours. Other colours include: black, green, blue, ivory, grey, white and yellow.

PEEK Plastic Machined Parts

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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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PEEK Plastic Machining

Your guide to PEEK Plastic Machining

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PEEK Guide: Properties, Applications and Design Considerations

What is PEEK?

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:

Note For Designers:

Finishing & Treatments:

Can we meet your PEEK plastic machining needs? Contact us now

PEEK UK Stock Sizes

Example PEEK Stock Sizes

PEEK Tube

PEEK Round Bar

PEEK Plate

PEEK Plastic Properties

PEEK Mechanical Properties

PEEK Thermal Properties

PEEK Electrical Properties

Other PEEK Properties

Frequently Asked Questions About PEEK

What kind of plastic is PEEK?

Can PEEK be machined?

Why is PEEK so expensive?

Is PEEK recyclable?

Is PEEK plastic food grade?

What is PEEK used for?

How strong is PEEK?

What colour is PEEK?

Further Reading & Resources

PEEK Plastic Machined Parts

Penta Precision provides the following plastic PEEK machining services:

Want to know more?

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Find out how we can help you

Plastic Machining

Industry Sectors

Commitment To Quality

Get A Quote