Ultem® Pei Screws, Hex Bolts, Custom Parts, and Other Fasteners

July 17, 2020

Ultem® PEI (polyetherimide)

Ultem® PEI is a semi-transparent high-temperature plastic. It is used to make custom parts as well as fasteners such as screws, hex nuts, washers, threaded studs, and spacers. It can be both molded and machined. Ultem® hardware is also available in glass-filled grades for enhanced strength and stiffness. (Glass-filled grades are opaque.) Ultem® 1000 is the natural grade, and Ultem® 2300 is the glass-filled grade.

Ultem® Pei Properties:


It is an amorphous plastic. Therefore, it has a molecular structure that lacks a continuous repeating form.

Ultem® PEI has no definite melting point. Its glass transition temperature (Tg) is 217º C (422º F).

The material exhibits extremely high strength and stiffness.

Continuous service temperature of 170º C (340º F).

High tensile modulus.

It is microwave clear.

Ultem® PEI parts are resistant to hot water and steam.

Broad chemical resistance up to high temperatures. Tolerates alcohols, acids, hydrocarbons, and others.

The material is hydrophobic. Therefore, it does not absorb water.

Retains 85% of its tensile strength after 10,000 hours in boiling water and 100% after 2,000 cycles in a steam autoclave at 270º C (518ºF).

Ultem® PEI has outstanding electrical properties.

It has the highest dielectric (insulating) strengths of any commercially available thermoplastic material. The dielectric constant is also stable.

RoHS Compliant.

It is inherently flame retardant with UL ratings of 94 V0, V2, and 5VA.

Very low smoke emissions.

Ultem® PEI is less expensive than other materials in its class, such as PEEK and PES.

The 1000 unfilled grade is FDA-compliant and USDA-approved.


However, Ultem® PEI will not stand up to alkali salts such as sodium bicarbonate, potassium cyanide, sodium sulfide, and others. Also, PEI shows stress cracking in chlorinated solvents, which include carbon tetrachloride, tetrachloroethylene, and others.

Examples of Ultem® Pei Applications

Submarines:  Ultem® 2300 flanged hex nuts are used to hold the sound tiles of submarines to the hull of the vessel. Ultem® is microwave clear. Therefore, sonar does not detect the hex nuts. It is also fire retardant, and in the case of fire, the parts have extremely low smoke emissions. Therefore, the lives of the crew are not endangered.

Cell Tower Antennas:  Ultem® 2300 set screws have been used extensively in antennas in cell phone towers in Europe. Their strength and the fact that they are microwave clear make Ultem® well suited to this application.

Particle Accelerators:  In a particle accelerator in England, Ultem® 2300 set screws have been used to insulate two sheets of metal from each other in an experiment. The clear microwave property of the material ensures the electrons from the particle accelerator will hit the experiment apparatus as the scientists intended.

AM/FM Radio Transmitters: Ultem® 1000 custom parts and fasteners are used to make these transmitters because the components are microwave clear.

Medical and Scientific Instruments: Ultem® 1000 is used for sterilization purposes in the medical industry. Parts can withstand repeated cycles in a steam autoclave making this material well-suited to the application. As mentioned above, Ultem® will retain 100% of its tensile strength after 2,000 cycles in a steam autoclave at 270º C (518º F).

MRI Machines:  Ultem® PEI cannot withstand continuous radiation. However, in short bursts, plastic performs well. MRI machines and other medical equipment are manufactured using Ultem® PEI custom parts and fasteners.

Trays and Containers for the Food Industry:  Ultem® 1000 is FDA and USDA-compliant as well as microwave clear. Trays and containers are unaffected by microwave cooking units. Therefore with a continuous service temperature of 170º C (340º F), this material is well suited for cooking and heating food.

Interested in learning more about how Ultem® PEI is right for your application? Contact one of our engineers by hitting the button below.



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