PL · engineering plastic
Polysulfone PSU (Udel equivalent)
A transparent, sterilisable high-temperature plastic that machines cleanly. It is the medical-device material when clarity, autoclave cycles and toughness are all needed at once.
Quoting this material
- Typical lead time
- 10–18 working days
- Condition
- Extruded stock or moulded components
- Achievable finish
- Ra 0.8 µm typical · Ra 0.4 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
A transparent, sterilisable high-temperature plastic that machines cleanly. It is the medical-device material when clarity, autoclave cycles and toughness are all needed at once.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 70 | MPa |
| Modulus of elasticity | 2.5 | GPa |
| Hardness | M69 | Rockwell |
| Continuous service temperature | 150 | °C |
| Thermal conductivity | 0.26 | W/m·K |
| Density | 1.24 | g/cm³ |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Extruded stock or moulded components
Heat treatment
No heat treatment; stress relieving is used on a machined part destined for repeated sterilisation, because stress plus hot water is a stress-cracking combination.
Achievable surface finish
Ra 0.8 µm
Ra 0.4 µm
Machines to a clean translucent finish; it is slightly amber-tinted rather than water-clear.
Tooling and cutting parameters
Cutting speed
- 150–400 m/min (sharp uncoated carbide)
Feed
- 0.10–0.30 mm/rev turning · 0.10–0.25 mm/tooth milling
Tooling
- Sharp uncoated carbide, high rake
Coolant
- Air or mist; keep it clear of solvent-based coolants
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Medical and surgical device components
- Sterilisable trays and tooling
- Food processing equipment parts
- Membrane housings and manifolds
- Transparent high-temperature covers
DFM notes for this grade
- Designed for repeated steam sterilisation at 134 °C: it holds its properties through many autoclave cycles where polycarbonate would craze and crack
- Not for solvent exposure - aromatic solvents attack it, which limits the cleaning agents it can see
- Transparency plus toughness plus temperature is the combination being bought; where any two of the three suffice, cheaper materials exist
Questions buyers ask
- Why choose PSU rather than polycarbonate for a medical part?
- Autoclave resistance. Polycarbonate crazes and cracks under repeated steam sterilisation at 134 °C; polysulfone survives hundreds of cycles. If the device is single-use, polycarbonate is cheaper and adequate; if it is reprocessed, PSU is the material.
- Is PSU suitable for chemical service?
- For aqueous and many process chemistries yes, but it is attacked by aromatic solvents and some ketones. Where the part sees aggressive solvents, PPS or PEEK is the safer selection.
Grades we would quote instead
PEI (Ultem)
5/10A hard, stiff, amber-coloured plastic that machines like a tough wood: clean chips, crisp edges and good dimensional stability.
PEEK
5/10Machines cleanly for a plastic but it holds heat at the cut and the swarf will not break.
Polycarbonate (PC)
6/10Tough and transparent, and it machines without cracking if the tooling is sharp and the depth of cut is light.