Ultem (PEI)
Also: PEI, polyetherimide, Ultem 1000, Ultem 2300 (30% glass-filled), Ultem 2100 / 2200 / 2400 (10, 20, 40% glass-filled), Ultem 9085 (FDM filament), Ultem 1010 (FDM filament), Duratron U1000, Tecapei, PEI-GF30
Ultem (PEI) is an amber, amorphous high-heat plastic: stiff to about 170 °C, inherently flame-resistant, sterilizable, and about half the price of PEEK.
Sourcing Ultem parts or stock?
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At a glance
| Density | 1.27 g/cm³ (0.046 lb/in³) |
|---|---|
| Tensile strength | 105-115 MPa (15-16.5 ksi) at yield |
| Yield strength | 105 MPa (15.2 ksi) tensile yield |
| Hardness | Rockwell M 109-112 (Rockwell R 125) |
| Elongation | 20-60% at break (molded specimens near 60%; extruded stock often lower) |
| Modulus of elasticity | 3.4-3.6 GPa (0.49-0.52 Msi) tensile; about 9 GPa (1.3 Msi) for 30% glass-filled Ultem 2300 |
| Thermal | Tg 217 °C (423 °F); amorphous, no melting point; continuous service about 170 °C (340 °F); HDT about 190-200 °C (375-392 °F) at 1.82 MPa |
| Composition | Polyetherimide, an amorphous polymer of aromatic imide and ether units (from bisphenol A dianhydride and m-phenylenediamine); unfilled, or 10-40% glass fiber in the 2000-series grades |
Typical values, Natural (amber) extruded rod and plate, unfilled Ultem 1000 type, dry, 23 °C (73 °F). Confirm against the mill certificate and the purchase spec.
- MachinabilityGood
- Machines cleanly and holds size: ±0.05 mm (±0.002") is practical. It is notch-sensitive and can stress crack, so use sharp carbide, air or plain water-soluble coolant with no aromatic or oil-based additives, and radius inside corners.
- WeldabilityGood
- Being amorphous, it solvent bonds with methylene chloride based cements and welds well by ultrasonic, hot-plate and laser methods. Epoxy, urethane and cyanoacrylate adhesives bond it after a light abrade and clean.
- FormabilityFair
- Dried sheet thermoforms and heat-bends above its 217 °C glass transition; aircraft interior panels and ducts are made this way. It needs much hotter forming and tooling than acrylic or polycarbonate; plate is machined, not bent.
- Corrosion resistanceGood
- Resists aliphatic hydrocarbons, alcohols, oils, fuels, dilute acids, hot water and steam (repeated autoclave cycles). Attacked by methylene chloride and other partially halogenated solvents, and by strong alkalis, especially hot. Absorbs about 0.25% water in 24 hours.
Ultem is the SABIC trade name for polyetherimide (PEI), an amorphous high-performance thermoplastic. Unfilled Ultem 1000 is translucent amber, yields at about 105 MPa (15 ksi), and keeps most of its stiffness up to its glass transition at 217 °C (423 °F). It is inherently flame-retardant with low smoke, dimensionally stable, a good electrical insulator, and it survives repeated steam autoclaving, which is why it shows up in aircraft interiors, electrical connectors, semiconductor test sockets and reusable medical devices.
Because it is amorphous, PEI behaves differently from the crystalline plastics around it. It has no sharp melting point, so it solvent bonds, thermoforms and ultrasonically welds well; it shrinks little and evenly in the mold, so molded parts hold tight tolerances; and it is transparent in thin sections. The flip side is stress cracking: residual machining stress plus the wrong coolant, cleaner or solvent (methylene chloride dissolves it) can craze a finished part. Glass-filled grades (Ultem 2100 to 2400, 10-40% glass) raise the modulus to about 9 GPa (1.3 Msi) at 30% glass and cut thermal expansion for structural and connector parts.
Ultem sits between the engineering plastics and PEEK. It costs roughly half as much as PEEK and machines a little more easily, but it is notch-sensitive, less tough in fatigue, and not suited to hot strong alkalis or continuous service much above 170 °C (340 °F). Ultem 9085 and 1010 filaments are also the standard high-temperature FDM materials for aircraft interior parts, fixtures and composite layup tooling.
Heat treatment
Not heat treated for properties. Stock shapes are stress relieved by the producer; after heavy roughing, or before bonding and aggressive cleaning, anneal machined parts at about 150-200 °C (300-390 °F), well below Tg, holding roughly an hour per 6 mm (1/4") of thickness, then cool slowly to limit stress cracking. Dry pellets and sheet before molding or forming.
Tempers and conditions
- Ultem 1000 (unfilled, amber)
- Black unfilled
- Glass-filled 10-40% (Ultem 2100, 2200, 2300, 2400)
- Medical grades (USP Class VI, ISO 10993 tested)
- Food-contact grades
- Ultem 9085 and 1010 FDM filament
- Thermoforming sheet
Stock forms
- Round rod
- Plate and sheet
- Tube
- Film
- Molding pellets
- FDM filament
Relative cost
Tier 4 of 5. Roughly half the price of PEEK and about 10-20x acetal per pound; glass-filled and medical grades cost more. Near-net rod and plate sizes pay back.
Typical applications
- Electrical connectors, insulators and coil bobbins
- Semiconductor test and burn-in sockets
- Reusable medical and dental instruments, sterilization trays
- Aircraft interior parts, ducts and brackets
- Fluid manifolds and valve bodies, including transparent inspection parts
- Food-service and microwave components
- Metallized lighting reflectors
- Composite layup tools and fixtures (printed Ultem 1010)
Process compatibility
How Ultem takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| CNC Machining | GoodGood | Machines well with sharp carbide; keep coolants and cleaners compatible, and anneal after roughing on tight-tolerance parts. |
| CNC Milling | GoodGood | Mills cleanly from plate; radius inside corners and avoid sharp notches at load points. |
| CNC Turning | GoodGood | Insulators, connector bodies and bushings from rod; holds tight diameters and concentricity. |
| Swiss Machining | GoodGood | Small connector pins, insulators and medical components from ground rod. |
| Injection Molding | ExcellentExcellent | A major high-heat molding resin: hot melt and mold, low and even shrink (about 0.5-0.7%), tight tolerances. Dry the pellets. |
| FDM 3D Printing | GoodGood | Ultem 9085 and 1010 print on industrial machines with heated chambers for aerospace interiors and tooling; printed parts are weaker across layers than molded. |
| Waterjet Cutting | GoodGood | Profiles plate without heat or added stress; finish-machine critical edges. |
| Laser Cutting | PoorPoor | Film and thin sheet cut; thicker material chars and leaves a stressed, heat-affected edge. Waterjet or mill instead. |
| Vibratory Finishing | GoodGood | Deburrs machined and molded parts; use plastic or ceramic media and a mild, compatible compound. |
| Bead Blasting | FairFair | Uniform matte finish or a bonding surface; mask sealing faces and clear areas. |
| Plating | FairFair | PEI is metallized and electroless plated for reflectors and EMI shielding, but it needs a specialty etch and a plater set up for it. |
| Anodizing | Not recommendedNot recommended | An aluminum process; plastics cannot be anodized. Buy black PEI or specify a molded colour. |
Compare Ultem
Design and sourcing tips
- Call out the grade: "Ultem 1000" (unfilled) for insulators and transparent parts, "Ultem 2300" (30% glass) for stiff, stable structural parts. Glass-filled grades are anisotropic when molded and abrasive to cut.
- List the chemicals, coolants and cleaners the part will see. PEI stress cracks in methylene chloride and other partially halogenated solvents and in hot caustic, and a machined part with residual stress fails first.
- Radius every inside corner, 0.5 mm (0.020") minimum, and keep sharp notches away from load points; PEI is notch-sensitive in impact and fatigue.
- For autoclaved medical parts, specify a medical grade with ISO 10993 or USP Class VI data and ask for annealed stock; residual stress plus repeated steam cycles is the usual failure.
- Thermal expansion is about 55 um/m·K unfilled and about 20-25 um/m·K in the flow direction at 30% glass, close to aluminum, which helps metal-to-plastic assemblies.
- Use PEEK instead above about 170 °C (340 °F) continuous, in hot strong alkalis, or where fatigue and wear dominate; use polycarbonate where heat stays under about 120 °C (250 °F) and cost matters.
Frequently asked questions
- What is Ultem made of?
- Ultem is the SABIC trade name for polyetherimide (PEI), an amorphous thermoplastic built from aromatic imide and ether groups. The imide groups give heat resistance and stiffness; the ether links add enough flexibility to melt-process it. Ultem 1000 is unfilled; the 2000 series adds 10-40% glass fiber.
- What temperature can Ultem withstand?
- Unfilled Ultem 1000 is rated for continuous service to about 170 °C (340 °F), with a heat deflection temperature near 200 °C (392 °F) at 1.82 MPa and a glass transition at 217 °C (423 °F). It has no sharp melting point; above Tg it softens and loses stiffness quickly. Above that range, PEEK or a polyimide is the next step.
- Is Ultem autoclavable?
- Yes. Ultem withstands repeated steam autoclaving, as well as ethylene oxide, gamma and hydrogen peroxide plasma sterilization, which is why it is used for reusable instrument handles and sterilization trays. Parts last longest when annealed and kept away from strong alkaline detergents.
- Can Ultem be glued?
- Yes, more easily than most high-performance plastics. Being amorphous, it solvent bonds with methylene chloride based cements and takes epoxy, urethane and cyanoacrylate adhesives after light abrasion and cleaning. It also ultrasonic welds well. PEEK, by contrast, resists solvents and is harder to bond.
- Is Ultem 9085 the same as Ultem 1000?
- No. Ultem 1000 is unfilled PEI for molding and stock shapes. Ultem 9085 is a PEI blend formulated for FDM printing and aircraft interior flammability rules; it prints more easily and is tougher, but its glass transition is lower, about 186 °C (367 °F). Ultem 1010 filament is closer to pure PEI and is used for hotter tooling.
Processes that commonly use it
Related materials
Where to verify these values
- SABIC Ultem 1000 and glass-filled grade resin data sheets
- Mitsubishi Chemical Advanced Materials Duratron U1000 and Ensinger TECAPEI stock-shape data
- Stratasys ULTEM 9085 and ULTEM 1010 filament data sheets
- ASTM D5205; ASTM D638 and D648 (heat deflection) test methods
