Ultem® PEI Fasteners: High‑Temperature Screws, Hex Bolts, and Custom Parts for Advanced Applications

Ultem® PEI (Polyetherimide)

Ultem® PEI is a semi‑transparent, high‑temperature thermoplastic renowned for its strength, stiffness, and chemical resistance. It can be molded or machined into a wide range of fasteners—screws, hex bolts, nuts, washers, studs, and spacers—as well as custom parts for demanding applications. The material is available in an unfilled natural grade (Ultem® 1000) and a glass‑filled variant (Ultem® 2300) that offers enhanced rigidity while remaining microwave‑clear.

Key Properties of Ultem® PEI

Advantages

• Amorphous structure: No continuous repeating polymer chain, contributing to excellent dimensional stability.
• Glass‑transition temperature 217 °C (422 °F); no fixed melting point.
• Exceptional strength and stiffness; high tensile modulus.
• Continuous service temperature up to 170 °C (340 °F).
• Excellent microwave transparency for RF and acoustic applications.
• Heat‑resistant to hot water and steam; retains 85 % tensile strength after 10,000 h boiling water and 100 % after 2,000 steam‑autoclave cycles at 270 °C (518 °F).
• Broad chemical resistance—tolerates alcohols, acids, hydrocarbons, and more.
• Hydrophobic; negligible water absorption.
• Outstanding electrical performance: highest dielectric strength among commercial thermoplastics, with a stable dielectric constant.
• RoHS compliant and UL‑rated V0/V2, 5 VA (self‑extinguishing, low smoke).
• Cost‑effective compared to PEEK or PES while delivering superior properties.
• Ultem® 1000 is FDA‑ and USDA‑approved, making it ideal for food‑grade applications.

Limitations

Ultem® PEI does not resist alkali salts such as sodium bicarbonate or potassium cyanide, nor does it resist stress cracking in chlorinated solvents (e.g., carbon tetrachloride, tetrachloroethylene).

Selected Applications

Submarine Structural Fasteners
Ultem® 2300 flanged hex nuts secure sonar‑sound tiles to hulls. Their microwave transparency keeps sonar blind, while flame‑retardancy and low smoke emissions protect crew safety during fire scenarios.

Cell‑Tower Antenna Hardware
Ultem® 2300 set screws are widely used in European telecom towers, where their strength and microwave clarity meet stringent performance demands.

Particle Accelerator Insulation
In a UK accelerator, Ultem® 2300 set screws insulated metal sheets, ensuring precise electron paths thanks to the material’s RF transparency.

AM/FM Radio Transmitters
Ultem® 1000 custom fasteners provide reliable, microwave‑clear components for broadcast equipment.

Medical & Scientific Instruments
Ultem® 1000 withstands repeated steam‑autoclave cycles at 270 °C, retaining full tensile strength after 2,000 cycles, making it ideal for sterilizable parts.

MRI Machines
While Ultem® PEI cannot endure continuous radiation, it performs reliably in short‑burst MRI settings, enabling the production of high‑quality, radiation‑resistant fasteners.

Food‑Industry Trays & Containers
Ultem® 1000, FDA/USDA‑approved and microwave‑clear, endures cooking temperatures up to 170 °C (340 °F) without degrading, making it ideal for microwave‑safe trays and containers.

Ready to integrate Ultem® PEI into your next project? Contact our engineering team by clicking the button below.