PEI Plastic Machining

Your guide to PEI Plastic Machining

__________

High performance amorphous thermoplastic

Typically transparent amber in colour

Commonly used for structural components requiring high strength and rigidity at elevated temperatures

PEI is a high performance thermoplastic with high mechanical strength and broad chemical resistance.

You may want to consider PSU (Polysulfone) as an alternative high performance thermoplastic which has similar characteristics but is cheaper and more readily available.

This guide will take you through the main attributes of PEI, 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 PEI machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

PEI Guide: Properties, Applications and Design Considerations

__________

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

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.

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

UK Stock Sizes

PEI 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

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

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