Amber-transparent, 170 °C continuous, inherently flame-retardant and the easiest of the high-temperature grades to machine. PEI is what fills the gap between commodity acrylic and PEEK: sterilisable, dimensionally stable and roughly a third of the cost of PEEK.
Values for an Ultem 1000 class unfilled grade. Glass-filled versions (10–30 %) raise stiffness and cut CTE, but lose the transparency that usually motivated the choice.
| Property | Value | Why it matters for machining |
|---|---|---|
| Glass transition | 217 °C | Annealing at 150 °C relieves stress without risking distortion |
| Continuous service temperature | 170 °C | Comfortably covers steam sterilisation at 134 °C, which PMMA and PC cannot take |
| Heat deflection temperature | ~200 °C at 1.82 MPa | Keeps its shape under load at autoclave temperature |
| Tensile strength | ~110 MPa | Higher than PC or PMMA; thin walls and fine ribs stay practical |
| Elongation at break | ~60 % | Tough rather than brittle — far more forgiving than PI or PBI |
| Flexural modulus | ~3.2 GPa | Similar to PMMA, so a straight substitution rarely changes deflection |
| Coefficient of thermal expansion | ~56 µm/m·K | Between PMMA and PEEK; allow for it in bonded metal assemblies |
| Water absorption | ~0.25 % / 24 h | Low enough that humidity is a secondary error, not the main one |
| Light transmission | ~80 %, amber tint | Usable as a sight glass or light pipe, but not where colour neutrality is required |
| Refractive index | 1.66 | High — relevant if you are coupling to optics or index-matching adhesives |
| Flammability | UL 94 V-0, low smoke | No additives needed; meets rail and aircraft interior requirements |
| Chemical resistance | Good, with exceptions | Attacked by strong bases, chlorinated solvents and some ketones; stress-crazes if cleaned with them |
| Cost index | 2.5–4 × PMMA | Roughly a third of PEEK — the value grade of the high-temperature family |
The transparent standard grade. Our default for manifolds, sight windows, medical housings and anything that needs visual inspection of the fluid path.
Improved melt-flow and release variants of the base grade; mechanically similar, sometimes easier to source in rod. We quote whichever is in stock.
Higher stiffness and lower CTE for structural brackets and fixtures. Opaque; expect more tool wear than unfilled.
Maximum stiffness and creep resistance in the PEI family. Chosen for load-bearing insulators where PEEK is not justified.
USP Class VI and ISO 10993 documentation, with lot traceability. Used for sterilisation trays, instrument handles and IVD housings.
Rod 6–150 mm, plate 6–75 mm, sheet. Unfilled plate is available in optical-quality sheet for windows up to 25 mm.
Sterilisation trays, instrument housings, IVD manifolds and dental components that need repeated autoclave cycles without PEEK pricing.
Connectors, coil formers, busbar supports and insulating plates: V-0 without additives, stable dielectric strength at temperature.
Wet-bench fixtures, wafer carriers and chemical-delivery components where transparency helps inspection and PI is over-specified.
Ducting components, brackets and trim parts meeting heat-release and smoke-density requirements.
Flow manifolds, valve bodies and cuvette holders with visible fluid paths and solvent resistance up to 150 °C.
Sight glasses, spray nozzles and guide rails that must survive CIP/SIP without clouding like PC does.
If you need clarity without amber, more heat, or a lower price, one of these replaces PEI cleanly.
Send the drawing and the sterilisation protocol. We will confirm grade, wall thickness and whether PEI or PSU is the better fit for your cycle count.
