PEI (ULTEM) Filament
Aerospace-grade high-temperature plastic. PEI — sold under the ULTEM brand — offers continuous service temperatures around 170 °C+, inherent flame retardancy (UL94 V-0), and excellent strength and chemical resistance, all while being more printable than PEEK.
What is PEI (ULTEM) filament?
PEI (Polyetherimide), best known by SABIC's brand name ULTEM, is an amorphous high-performance thermoplastic with a glass transition around 215 °C and continuous-use temperatures near 170 °C+. It is inherently flame retardant (UL94 V-0) with very low smoke, high strength and stiffness, and strong chemical resistance.
Those properties make it a staple in aerospace interiors, electronics, and medical applications. Being amorphous, PEI is somewhat easier to print than semi-crystalline PEEK, but it still needs a high-temperature hotend (360 °C+), a heated chamber, and thorough drying. Common printable grades include ULTEM 9085 and 1010.
PEI vs PEEK vs PC — how to choose
Position PEI between mainstream engineering plastics and PEEK:
PEI is the sweet spot when you need high heat and built-in flame retardancy without full PEEK complexity.
Printing PEI (ULTEM) successfully
- High-temp printer — 360 °C+ hotend, heated chamber, and high-temp bed.
- Dry thoroughly — PEI is hygroscopic and moisture wrecks strength and surface.
- Warm chamber to control warping and build interlayer strength.
- Strong first-layer adhesion — PEI pulls hard as it cools.
- Follow grade-specific profiles (e.g. 9085 vs 1010) from the datasheet.
PEI (ULTEM) brands stocked at Rev1
Rev1 Technologies stocks PEI / ULTEM filament from multiple brands, all shipped from Auburn Hills, Michigan with real phone support. Use the brand filter below to narrow the range, or call (248) 707-2950 for spec, bulk, and color-match help.