NBR is the workhorse oil seal material. It resists mineral oils, greases, hydraulic fluids and aliphatic hydrocarbons, moulds easily, and costs a fraction of FKM — which is why the majority of O-rings, shaft seals and fuel lines in general industrial service are nitrile. Its weakness is weather: NBR degrades in ozone and UV, so outdoor applications need a protective compound or a different polymer.
Typical values for standard moulding grades. Exact figures depend on the specific compound or grade — confirm against your drawing before quoting.
Key properties
| Własność | Typical value |
|---|---|
| Hardness range | 40 – 90 Shore A |
| Service temperature | -40 to +120 °C |
| Tensile strength | 7 – 15 MPa |
| Elongation at break | 200 – 500 % |
| Compression set (22 h / 100 °C) | 15 – 30 % |
| Oil resistance | Excellent in mineral oils and greases |
Values are typical for unfilled moulding grades at 23 °C unless stated. Glass-filled and specialty grades differ.
Typical applications
- O-rings and rotary shaft seals
- Hydraulic and pneumatic seals
- Fuel and oil hoses
- Gaskets for gearboxes and pumps
- Rollers and industrial moulded goods
Processing notes
- Acrylonitrile content decides the balance: higher ACN means better oil resistance but worse low-temperature flexibility. Specify the service temperature and we will pick the grade.
- NBR is not suitable for outdoor exposure without protection. Ozone attack shows as surface cracking within months.
- Poor resistance to ketones, esters, ethers and strong acids. Confirm the media.
- Sulphur-cured NBR is standard; peroxide-cured gives better set resistance and heat ageing at higher cost.
Frequently asked questions
What ACN content do I need?
Around 34 % for general oil service, 40 % and above for aggressive oils and higher temperatures, and 28 % or lower when flexibility below -40 °C matters more than oil resistance. Give us the fluid and the temperature and we will specify.
NBR or HNBR?
NBR for service to 120 °C in clean oil. HNBR when the same oil runs hotter, or when ozone and ageing resistance matter — it is the same chemistry with the double bonds hydrogenated out.
Related materials
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Send us your NBR Nitrile Rubber drawing
Upload a 3D model or a 2D drawing and we will come back with a DFM review, a tooling cost and a piece price — usually within two working days.
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