Ultem 1000 and glass-filled 2300 polyetherimide — the flame-smoke-toxicity polymer of aircraft interiors and the dielectric workhorse of instrumentation, machined to print in the United States.
Ultem — polyetherimide, or PEI — owes its career to a fire requirement. When an aircraft cabin material burns, what kills is rarely the flame: it is the smoke and its toxicity. Ultem's amorphous imide backbone is inherently flame-resistant without additives, generates remarkably little smoke, and what it does emit is comparatively low in toxicity — the flame-smoke-toxicity (FST) triad that aircraft interior specifications are written around. That is why the transparent amber polymer shows up throughout cabin and avionics hardware, and why "machined from Ultem" appears on so many aerospace and aviation prints. The same chemistry brings a second career: PEI is one of the best dielectric materials that can be precision machined, holding its insulating properties across temperature and frequency, which puts it inside test fixtures, connector bodies, and RF hardware across the instrumentation world. Add continuous service capability to roughly 170°C, tolerance of repeated steam autoclaving, and hydrolytic stability, and Ultem occupies the wide, useful territory between everyday acetal and premium PEEK in our plastics lineup.
The default grade: transparent amber, tough for an amorphous high-heat polymer, and the more forgiving of the two to machine. Specified on insulators, standoffs, connector bodies, sight windows where amber tint is acceptable, sterilization trays, and general FST-driven cabin hardware.
Glass fiber roughly doubles stiffness, sharply improves creep resistance under sustained clamping loads, and cuts the thermal expansion coefficient — the grade for structural brackets, fixture plates, and bolted hardware that must hold dimension under load at temperature. The trades: abrasive to tooling, opaque, and less tough at sharp corners, so inside radii deserve generosity on the drawing.
Ultem is amorphous where PEEK is semi-crystalline, and it machines accordingly: stiffer-feeling under the tool, excellent detail and thread quality, but more notch-sensitive and less forgiving of dull edges, dwell heat, and aggressive interrupted cuts — stress risers that a PEEK part shrugs off can start a crack in PEI. Sharp polished tooling, coolant chosen to avoid stress-cracking agents, generous corner radii, and stress-relief annealing on heavily machined blanks keep Ultem parts crack-free through service. Its lower moisture uptake and amorphous stability actually make it slightly easier than PEEK to hold flat and stable across large machined faces.
Ultem stock typically prices at a fraction of PEEK — often several times cheaper on a like-for-like blank — while clearing the requirements a large share of "PEEK" prints actually contain. When a drawing calls PEEK but the duty is dielectric, FST, or sub-170°C thermal, we will quote the Ultem alternative alongside it. When the duty is hot aggressive chemistry or a wear interface, PEEK stays, because strong solvents and alkalis attack PEI.
Machined Ultem work splits between prismatic and turned geometry, and the network covers both. Insulator plates, test-fixture bodies, and cabin-hardware brackets run on VMCs with travels to 32.5" × 20.5" × 20.1", with multi-face parts consolidated onto the 5-axis trunnion mill — 19" table, 18,000 RPM spindle, 60 tools — where high spindle speed pairs naturally with the small, sharp cutters fine PEI detail wants. Turned connector bodies and bushings run on lathes with 1.625" to 3.05" bores, and small-diameter production insulators run on Swiss-type platforms from .812" to 1.50" bar. Work-holding is gentle and finish passes are planned at temperature, per standard plastics discipline; on rigid PEI we hold ±.0005" or better on critical features, with tighter callouts quoted per-feature through the tight-tolerance process. Full material certifications and lot traceability ship with FST-driven aerospace work as a matter of course.
The aerospace stream covers cabin and avionics hardware — brackets, bezels, ducting components, and latch and mechanism parts machined against FST requirements. The electrical stream is at least as large: high-voltage insulators and standoffs, semiconductor test-socket and burn-in fixture bodies that hold dimension through thousands of thermal cycles, and RF hardware exploiting PEI's stable dielectric constant. Medical programs use Ultem for reusable instrument handles and sterilization hardware that survive repeated autoclaving, and R&D groups reach for it whenever a fixture must be an insulator at temperature. Prototype-to-production is a natural arc here: machined prototypes validate the design in genuine certified material before any molding decision.
Ultem wins on dielectric duty, FST compliance, autoclave tolerance, and service to roughly 170°C — at a fraction of PEEK's price. PEEK wins on temperature headroom, harsh chemistry, and wear interfaces. Many PEEK prints can step down; we quote the alternative when the requirements allow.
1000 (unfilled) is tougher, transparent amber, and easier to machine — the default. 2300 (30 percent glass) is roughly twice as stiff with better creep resistance and lower expansion, for structural parts under sustained load, at the cost of abrasive machining and notch sensitivity.
The material family's flame, smoke, and toxicity behavior is why it is a standard cabin callout, and compliance rides on the certification of the specific stock shipped — so full material certs and lot traceability accompany our aerospace Ultem work.
The full engineering-plastics family we machine to print.
The step up for temperature headroom, chemistry, and wear duty.
The precision plastic for room-temperature mechanisms and bushings.
The metal alternative when conductivity is acceptable and stiffness rules.
Where FST-driven Ultem hardware ships alongside metallic structure.
5-axis milling, Swiss turning, and inspection across an ISO 9001:2015 certified production network.
