| Property | Value |
|---|---|
| Temperature range | -40 °C to +80 °C |
| Hardness | 60–95 Shore A, up to 75 Shore D |
| Best at | Abrasion, tensile, tear, load capacity |
| Contains fluorine | No |
Polyester or polyether decides the part
This is the distinction that matters more than anything else on a urethane drawing. Polyester urethane (AU) has the better mechanical properties and the better oil resistance. Polyether urethane (EU) has far better hydrolysis resistance, meaning it survives hot water and humidity that would break a polyester grade down into a sticky mess.
A wear pad in a dry plant should be polyester. The same pad in a wash-down environment or outdoors in a humid climate should be polyether, and specifying the wrong one produces a part that performs beautifully for a year and then disintegrates. We ask about moisture on every urethane enquiry for this reason.
How we compound and test it
Hardness range extends into Shore D territory, which puts urethane in a space between rubber and plastic where the usual elastomer intuitions stop applying. Load-deflection behaviour is not proportional to hardness across that range, so for a load-bearing part we work from the deflection you need rather than from a durometer number.
Heat is the other limit. Above roughly 80 °C continuous, mechanical properties fall away quickly, and internal heat build-up in a fast-cycling part can push a component past that limit even in a cool room.
The two mistakes buyers make
The first is specifying urethane for a hot application because the abrasion number is attractive. The abrasion advantage disappears with the heat resistance, and there is no urethane grade that behaves like a fluoroelastomer.
The second is specifying a hardness rather than a load. Urethane is usually chosen because a part has to carry something, and hardness is a poor proxy for load capacity in this family in particular.