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PEI Plastic Sheet (ULTEM): Properties, Processing & Applications Guide

Key Properties of PEI Sheet

Mechanical Properties

Property	Value	Standard
Tensile strength	105 MPa	ISO 527
Tensile modulus	3.0 GPa	ISO 527
Flexural strength	150 MPa	ISO 178
Flexural modulus	3.3 GPa	ISO 178
Impact strength (Charpy, notched)	5 kJ/m²	ISO 179
Hardness (Rockwell)	M109	ASTM D785

Thermal Properties

Property	Value
Glass transition temperature (Tg)	217°C
Continuous service temperature	170°C
HDT (1.8 MPa)	200°C
Thermal conductivity	0.22 W/m·K
CLTE	5.6 × 10⁻⁵ /°C

Fire Performance (Inherent, No Additives)

Test	Result
UL94 V-0	Pass at 0.4mm
Limiting Oxygen Index (LOI)	47%
OSU heat release (65/65)	Pass
Smoke density (Ds, 4 min)	< 30
NBS smoke (flaming)	Ds max < 70

Physical Properties

Property	Value
Density	1.27 g/cm³
Water absorption 24h	0.25%
Refractive index	1.66 (amber-transparent)

PEI vs Other Engineering Plastics

Property	PEI	PEEK	PPS	POM
Service temp (°C)	170	250	200	100
Tensile (MPa)	105	98	70 (unfilled)	70
Fire rating	V-0 (inherent)	V-0 (inherent)	V-0	HB
Cost index	25	100	15	5
Transparency	Amber-clear	Opaque	Opaque	Opaque
FDA compliant	✓	✓	✗	✓

PEI offers the best value when fire retardancy + high strength + transparency are all required.

Processing Methods

CNC Machining

PEI is easily machined with standard CNC equipment:

· Use carbide tools with positive rake

· Cutting speed: 100–300 m/min

· Feed: 0.05–0.15 mm/rev

· No coolant needed for light cuts

· Achievable tolerance: ±0.05mm

Thermoforming

PEI sheets can be thermoformed at 180–200°C:

· Pre-dry sheets at 150°C for 4 hours before forming

· Mould temperature: 130–150°C

· Forming vacuum: 0.08–0.1 MPa

Bonding & Welding

· Adhesive bonding: epoxy or polyurethane adhesives

· Ultrasonic welding: frequency 20–40 kHz

· Hot plate welding: 320–350°C plate temperature

· Vibration welding: 100–240 Hz, 0.7–1.8mm amplitude

Applications by Industry

Aerospace

· Interior panels and trim

· Air ducting and ventilation

· Window masks and surrounds

· Seat armrest components

Medical

· Surgical instrument handles

· Sterilisation trays

· Dental instrument components

· Diagnostic equipment housings

Electronics

· PCB connectors

· Chip carriers

· Switch housings

· LED reflectors

Industrial

· Sight glasses (transparent grades)

· Pump and valve components

· Food processing equipment

· Analytical instrument parts

For comparison with PEEK, see our PEEK vs PEI guide. For aerospace applications, read Engineering Plastics in Aerospace.

FAQ

Q1: Is PEI the same as ULTEM?

PEI (polyetherimide) is the generic material name. ULTEM is the brand name for PEI manufactured by SABIC. Other manufacturers produce PEI under different brand names (e.g., TECAPEI by Ensinger). NAGOMER supplies PEI sheets manufactured to the same material specifications.

Q2: What temperature can PEI sheets withstand?

PEI has a glass transition temperature of 217°C and a continuous service temperature of 170°C. Its heat deflection temperature (HDT) at 1.8 MPa is 200°C. PEI can withstand short-term thermal excursions up to 200°C.

Q3: Is PEI FDA compliant?

Yes, PEI is FDA compliant for food contact under 21 CFR. Natural (unfilled) PEI grades meet food contact requirements and can be used in food processing equipment and food-contact surfaces.

Q4: How does PEI compare to PEEK in cost?

PEI typically costs 60–70% less than PEEK. While PEEK offers higher temperature resistance (250°C vs 170°C) and better chemical resistance, PEI provides comparable mechanical strength and inherent flame retardancy at a fraction of the cost.

Looking for PEI/ULTEM sheets? Contact NAGOMER for specifications and pricing, or explore our PEI products and PEEK alternatives.

NAGOMER — Professional Engineering Plastics Solutions

www.nagomer.com | info@nagomer.com