Materials → Polyurethane
Material profile · 01/06
POLYURETHANE
The default choice for dynamic rod, piston, and wiper seals under abrasive load.
- -30°C to 110°C
- Temp. range
- 85-95 Shore A
- Hardness
- Low-medium
- Friction
- Excellent
- Abrasion resistance
Overview
Where Polyurethane earns its place.
Polyurethane is the general-purpose workhorse of hydraulic sealing. It combines high tensile strength with excellent resistance to abrasion and extrusion, which is why it dominates dynamic sealing positions — rod seals, piston seals, and wiper seals — where a seal lip repeatedly moves across a metal surface. Compared with standard rubber compounds, PU holds its shape better under pressure and resists nicking from small hard particles in the fluid, extending service life in cylinders that see frequent cycling.
Used in
Best-fit industries
Trade-offs
Advantages and limitations.
Advantages
- High tensile strength and tear resistance for long dynamic seal life.
- Strong extrusion resistance at moderate to high system pressure.
- Good compression set behaviour compared with standard elastomers.
- Machinable and mouldable into custom lip and wiper profiles.
Limitations
- Performance drops at sustained high temperature; not the first choice above ~100°C continuous.
- Limited compatibility with some phosphate-ester and ketone-based fluids.
- Can absorb moisture over long-term water exposure, softening the compound.
Operating envelope
Typical technical reference.
Figures are typical for the compound family and vary by specific grade and cure. Confirm exact limits against your fluid, pressure, and duty cycle before finalising a specification.
| Operating temperature | -30°C to 110°C (grade dependent) |
| Typical hardness | 85-95 Shore A |
| Friction coefficient | Low to medium |
| Fluid compatibility | Mineral oils, most hydraulic fluids |
| Duty type | Dynamic — rod, piston, wiper |
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See the other five materials.
Engineering support
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