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PEI plastic machined parts

PEI is a high-performance thermoplastic with strong mechanical strength and broad chemical resistance. PSU offers similar properties at lower cost and better availability. This guide covers attributes, applications, finishing, stock sizes, and properties.

High-performance amorphous thermoplastic
Transparent amber colour

PEI plastic machined parts

PEI is a high-performance thermoplastic with strong mechanical strength and broad chemical resistance. PSU offers similar properties at lower cost and better availability. This guide covers attributes, applications, finishing, stock sizes, and properties.

High-performance amorphous thermoplastic
Transparent amber colour

PEI plastic machined parts

PEI is a high-performance thermoplastic with strong mechanical strength and broad chemical resistance. PSU offers similar properties at lower cost and better availability. This guide covers attributes, applications, finishing, stock sizes, and properties.

High-performance amorphous thermoplastic
Transparent amber colour

PEI plastic grades we use

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What is PEI?

PEI (Polyetherimide) is a high performance amorphous thermoplastic which is typically transparent amber in colour.

PEI plastic is commonly used for structural components requiring high strength and rigidity at elevated temperatures as well as broad chemical resistance.

Please see our PSU (Polysulfone) page for an alternative high performance thermoplastic which has similar characteristics but is cheaper and more readily available.

How PEI is machined will depend on whether it is an unfilled or glass-filled grade being used.

The unfilled can be machined with standard high speed steel cutting tools, the reinforced grade will require hard metal tools. Penta Precision has plenty of experience machining high performance engineering plastics and we will use the correct tools, speeds and feeds for the job.

Water soluble, non-aromatic coolant needs to be used in order to avoid stress cracking.

You may also see PEI referred to as:

  • TECAPEI®
  • Ultem® / Ultem 1000
  • Duratron® PEI
  • SUSTAPEI

Main attributes

  • High mechanical strength
  • High rigidity
  • Very good dimensional stability
  • Relatively high long term service temperature
  • Flame resistant
  • Good chemical resistance
  • Excellent electrical properties
  • High strength to weight ratio
  • Glass-filled grade available
  • Low thermal conductivity
  • Highest dielectric strength of any thermoplastic
  • Transparent amber
  • High tensile strength
  • Semi transparent
  • Good UV resistance and weatherability
  • Most grades suitable for use with food
  • Can withstand dry heat sterilisation at 180°C, ethylene oxide gas and gamma radiation

Common Applications

  • Reusable medical devices
  • Electrical components
  • Surgical & dental instruments
  • Radomes
  • Thermostat housings
  • Bezels
  • Reflectors & lighting fixtures
  • Gears & driveshafts
  • Bearings & bushings

Note for designers

The cost of PEI is higher than conventional engineering plastics and therefore is advised to only be used where the properties are required, i.e. highly demanding applications.

We prefer to work with the cheaper and more readily available Polysulfone (PSU) which has similar characteristics.

UK stock sizes

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

Stock sizes vary by supplier. Below are the standard stock sizes for Ultem® 1000. We recommend the more readily available PSU (Polysulfone) as a cheaper alternative to PEI.

PEI Sheet

  • Dimensions: 12in x 12in to 24in x 48in
  • Thickness 0.060in to 3in

PEI Rod

  • Outside Diameter: 0.250in to 6in

Technical properties

Here are the properties for TECAPEI natural which is an unfilled, unreinforced PEI brand. Reinforced and modified grades will have different properties.

TECAPEI Properties

Mechanical properties

Mechanical Properties

 Value Parameter Norm Notes
Modulus of Elasticity
(tensile test)		 3200 MPa 1mm/min DIN EN ISO 527-2 For tensile test: specimen
type 1b
Tensile Strength  127 MPa 50mm/min DIN EN ISO 527-2  
Tensile Strength at Yield 127 MPa 50mm/min DIN EN ISO 527-2  
Elongation at Yield 7% 50mm/min DIN EN ISO 527-2  
Elongation at Break 35% 50mm/min DIN EN ISO 527-2  
Flexural Strength 164 MPa 2mm/min, 10 N DIN EN ISO 178 For flexural test: support span 64mm, norm specimen
Modulus of Elasticity (flexural test) 3300 MPa 2mm/min, 10 N DIN EN ISO 178  
Compression Strength 23/41/92 MPa 1% / 2% / 5% 5mm/min, 10 N EN ISO 604 Specimen 10x10x10mm
Compression Modulus 2800 MPa 5mm/min, 10 N EN ISO 604

Specimen 10x10x50mm, modulus range between 0.5 and 1% compression.
Impact Strength (Charpy) 113 kJ/m2 max. 7.5J DIN EN ISO 179-1eU For Charpy test: support span 64mm, norm specimen
Ball Indentation Hardness 225 MPa   ISO 2039-1 Specimen in 4mm thickness
Thermal properties

Thermal Properties

 Value Parameter Norm Notes
Glass Transition Temperature 216°C   DIN EN ISO 11357 Found in public sources
Melting Temperature N/A   DIN EN ISO 11357  
Service Temperature 200°C short term   Found in public sources. Individual testing regarding application conditions is mandatory
Service Temperature 170°C long term    
Thermal Expansion (CLTE) 5 10-5 K-1 23-60°C, long DIN EN ISO 11359-1;2  
Thermal Expansion (CLTE) 5 10-5 K-1 23-100°C, long DIN EN ISO 11359-1;2  
Thermal Expansion (CLTE) 6 10-5 K-1 100-150°C, long DIN EN ISO 11359-1;2  
Specific Heat 1.2 J/(g*K)   ISO 22007-4:2008  
Thermal Conductivity 0.21 W/(K*m)   ISO 22007-4:2008  
Electrical properties

Electrical Properties

 Value Norm
Specific Surface Resistance 1014 Ω DIN IEC 60093
Specific Volume Resistance 1014 Ω*cm DIN IEC 60093
Other properties

Other Properties

 Value Parameter Norm Notes
Water Absorption 0.05 / 0.1% 24h / 96h (23°C) DIN EN ISO 62 Ø ca. 50mm, h=13mm
Resistance to hot water/bases +     + good resistance
Resistance to weathering -     - poor resistance
Flammability (UL94) V0 Corresponding to DIN IEC 60695-11-10 Corresponding means no listing at UL (yellow card). The information might be taken from resin, stock shape or estimation. Individual testing regarding application conditions is mandatory.
Density 1.28 g/cm3      

Industries that use PEI plastic

PEI plastic FAQs

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