PEI (Ultem)
High-performance amorphous thermoplastic with flame resistance, high strength, and excellent dimensional stability. PEI is used in aerospace interiors and electrical components.
About PEI (Ultem)
PEI (Polyetherimide), marketed as Ultem, is a high-performance amorphous thermoplastic that bridges the gap between commodity plastics and PEEK. It offers continuous use at 170°C, inherent flame resistance (UL94 V-0 without additives), and excellent dimensional stability.
FabRapid CNC machines Ultem 1000 (unfilled) and Ultem 2300 (30% glass-filled) for aerospace interiors, electrical connectors, and medical components. PEI machines cleanly with good surface finish and tight tolerances.
PEI is approximately one-third the cost of PEEK while providing similar chemical resistance and flame retardancy. For applications where PEEK's extreme temperature capability (250°C) is not needed, Ultem offers excellent value.
Material Properties
Compatible Manufacturing Processes
PEI (Ultem) can be processed using these manufacturing methods.
Available Surface Finishes
Surface treatments compatible with PEI (Ultem).
Common Applications
Design Guidelines for PEI (Ultem)
Anneal PEI parts after machining — residual stresses can cause cracking in contact with certain chemicals
Minimum wall thickness: 0.8 mm — PEI machines cleanly with good edge definition
Glass-filled Ultem 2300 has 2× the flexural modulus of unfilled Ultem 1000 — specify when stiffness is critical
PEI is transparent in amber — useful for visual inspection windows in high-temperature applications
PEI (Ultem) FAQ
PEEK offers higher continuous use temperature (250°C vs 170°C), better chemical resistance, and higher strength. Ultem is less expensive (approximately 1/3 the cost), equally flame retardant, and available with transparent grades. For aerospace interiors and electrical components under 170°C, Ultem is often the better value choice.
Yes. Ultem 1000 is FDA and NSF compliant for food contact. It is also USP Class VI compliant for medical device applications. Its autoclave resistance makes it suitable for reusable medical instruments and food processing equipment.
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