This image was created with artificial intelligence – marked under Art. 50 of the AI Act, Regulation (EU) 2024/1689. It is a placeholder until the company's photos arrive.Selecting seals for automotive engineering
Flat gaskets made of rubber in NBR, EPDM, FKM & silicone. Find out all about applications, selection criteria and custom-made parts.
Seals perform a central function in vehicle engineering: they protect systems against leaks, safeguard components and ensure the long-term functionality of components under sometimes extreme conditions. In a vehicle, temperature changes, media contact, mechanical loads and environmental influences all act on the materials used at the same time. This results in a high level of complexity when it comes to selection.
In practice, it becomes clear that many failures are not attributable to the design but to an unsuitable choice of material. Even small deviations in temperature resistance or media resistance lead to embrittlement, swelling or leaks. A well-founded selection significantly reduces these risks and increases the service life of the entire assembly.
Are you faced with the task of choosing a suitable seal for your application? Then three factors matter: medium, temperature and mechanical load.
Requirements for seals in vehicle engineering
Vehicles combine a wide variety of operating conditions. Seals must therefore meet several requirements at the same time:
- Temperature resistance (from cold to engine heat)
- Resistance to oils, fuels and chemicals
- Pressure and vibration resistance
- Ageing and weather resistance
- Dimensional stability under continuous load
Depending on the installation location, these requirements vary considerably. A seal in the engine compartment places different demands than a seal in the interior or on the body.
Materials at a glance
Choosing the right material forms the basis for a functioning seal. Different elastomers react very differently to temperature, media and mechanical load. There is no one-size-fits-all solution, as every material has specific strengths and limits. It is therefore crucial to match the material precisely to the specific application in the vehicle.
Below you will find an overview of the most important materials and their typical areas of application.
EPDM
EPDM is eminently suitable for applications involving water, steam and environmental influences. The material shows high resistance to ozone and UV radiation and remains flexible even at changing temperatures. This makes it particularly suitable for components that are permanently exposed to environmental influences or are in contact with cooling media. Typical areas of application are door seals and components in the cooling circuit.
NBR
NBR is the standard for oil- and fuel-resistant applications. The material offers very good resistance to mineral oils and fuels and at the same time has solid mechanical properties. As a result, it is preferentially used in areas where media contact and mechanical load occur together, for example in fuel systems or hydraulic applications.
FKM (Viton)
FKM is used wherever high temperatures and aggressive media occur. The material is characterised by exceptionally high temperature resistance and excellent chemical resistance. This makes it particularly suitable for demanding applications in the engine compartment where standard materials reach their limits.
Silicone
Silicone is used when a very wide temperature range and high flexibility are required. The material remains elastic even at extreme temperatures and is therefore suitable for applications where other elastomers would become brittle. Typical areas of application are found in electronics, sensor technology and in components with lower mechanical load.
Selection by specific application
Engine compartment
- High temperatures and oil load at the same time
- Mechanical stress from vibration and pressure
- Suitable materials: FKM, NBR
Fuel system
- Contact with petrol and diesel
- High demands on media resistance
- Suitable materials: NBR, FKM
Cooling circuit
- Water and temperature fluctuations in focus
- Permanent elasticity required
- Suitable material: EPDM
Exterior and body
- Weather, UV radiation and ozone exposure
- Long-term ageing resistance required
- Suitable material: EPDM
Typical areas of application in the vehicle
The requirements differ considerably depending on the assembly:
| Area | Requirements | Typical materials |
|---|---|---|
| Engine compartment | Heat, oil, pressure | FKM, NBR |
| Cooling circuit | Water, temperature changes | EPDM |
| Fuel system | Fuels, pressure | NBR, FKM |
| Body | Weather, UV | EPDM |
| Interior | Flexibility, ageing | Silicone |
Temperature and media matrix
| Material | Temperature range | Media resistance |
|---|---|---|
| EPDM | -40 to +120 °C | Water, coolant |
| NBR | -30 to +100 °C | Oils, fuels |
| FKM | -20 to +200 °C | Aggressive media, chemicals |
| Silicone | -60 to +200 °C | Limited chemical resistance |
Decision logic (practical)
| Step | Question | Recommendation |
|---|---|---|
| 1 | Medium? | Oil/fuel → NBR or FKM · Water/coolant → EPDM |
| 2 | Temperature? | >150 °C → FKM · <120 °C → EPDM/NBR |
| 3 | Chemistry? | Aggressive media → FKM |
| 4 | Exterior/UV? | Weather → EPDM |
| 5 | Movement/pressure? | Dynamic/high → NBR or FKM |
Selection criteria in practice
For the right selection, you should proceed systematically:
1. Define the medium Which substances come into contact with the seal? Oil, water, fuel or chemicals determine the choice of material.
2. Determine the temperature range Continuous and peak temperatures must be taken into account.
3. Check the mechanical load Pressure, movement and vibration influence the service life.
4. Analyse the installation situation Shape, tolerances and assembly conditions play a role.
5. Define the service life requirement Depending on the application, long-term resistance may be required.
Standards and requirements in the automotive sector
Specific standards and quality requirements apply in vehicle engineering. These include, among others, DIN and ISO standards for seals as well as manufacturers' internal specifications. These define requirements for material properties, tolerances and service life.
Compliance with these standards ensures consistent quality and enables safe integration into existing systems.
Service life and maintenance
Elastomers are subject to a natural ageing process. Temperature, UV radiation, ozone and media contact significantly influence the service life. Regular inspection and planned replacement increase operational safety and prevent unplanned failures.
Manufacturing techniques
Depending on the requirement, seals are produced using different processes. Waterjet cutting enables precise contours without thermal load. Punching is suitable for large quantities with consistent quality. CNC processes are used for complex geometries and enable high accuracy.
Comparison of materials
| Material | Advantages | Limits | Typical errors | Area of application |
|---|---|---|---|---|
| EPDM | Weather-resistant, flexible | not oil-resistant | Use with oil → swelling | Exterior, cooling circuit |
| NBR | Oil- and fuel-resistant | limited UV resistance | Outdoor use → cracks | Hydraulics, fuel system |
| FKM | High temperature and chemical resistance | higher price | Overdimensioning for simple applications | Engine compartment |
| Silicone | Extremely temperature-resistant | weaker chemical resistance | Use with oil → material degradation | Electronics, sensor technology |
Avoiding errors in selection
Typical errors usually arise from incomplete requirements:
- Selecting material based on price alone
- Ignoring temperature peaks
- Underestimating media resistance
- Not taking mechanical load into account
Even small deviations lead to leaks or premature wear.
Further topics
You can find more in-depth content here:
This content helps with selection and design for specific applications.
Custom manufacturing and cut to size
When standard solutions reach their limits, individual manufacturing offers clear advantages. Particularly with complex geometries, high requirements or tight tolerances, dimensionally accurate cut pieces provide significantly higher operational safety.
How to proceed (enquiry)
- Define the area of application (medium, temperature, installation location)
- Provide a drawing or dimensions
- Clarify requirements for service life and load
- Select a suitable material or have one checked
A structured enquiry speeds up selection and reduces wrong decisions.
Standard solutions cover many applications but quickly reach their limits with specific requirements. In such cases, dimensionally accurate cut to size offers clear advantages, as the seal is adapted exactly to the geometry and load situation.
Individual manufacturing allows fit accuracy, assembly effort and operational safety to be optimised in a targeted way. At the same time, material thicknesses, tolerances and contours can be defined exactly, which makes a decisive difference in practice, particularly with complex assemblies.
Individual seals are manufactured on the basis of drawings or specific specifications and enable precise matching to the respective application in the vehicle.
Frequently asked questions
Which seal is suitable for the engine compartment?
FKM and NBR are primarily suitable for the engine compartment. FKM is suitable for very high temperatures and aggressive media. NBR is appropriate when oil and fuel resistance is required and the temperature load remains within the usual range.
Which material is suitable for seals in the fuel system?
NBR or FKM are usually used for fuel systems. Both materials offer good resistance to petrol and diesel. With higher thermal or chemical requirements, FKM is often the better choice.
When is EPDM the right choice?
EPDM is very suitable for applications involving water, coolants, ozone, UV radiation and environmental influences. Typical areas of application are cooling circuits, door seals and seals in the exterior area.
Why is media resistance so important for seals?
Media resistance determines whether a seal remains functional in the long term. If an unsuitable material comes into contact with oil, fuel or chemicals, the material can swell, harden, crack or become leaky.
What role does temperature play in selection?
Temperature is one of the most important selection criteria. In addition to the continuous temperature, short-term temperature peaks must also be taken into account. A material that is thermally overloaded loses elasticity and sealing effect.
When is a custom-made seal worthwhile?
Custom manufacturing is always suitable when standard dimensions do not cleanly cover the requirements for fit, load or installation situation. This improves operational safety and reduces assembly problems.
Which errors occur particularly frequently during selection?
Temperature peaks, media contact or mechanical loads are often assessed too superficially. Selecting based on price alone is equally problematic. In practice, such decisions often lead to premature wear or leaks.
How do I best proceed when selecting a seal?
First, the medium, temperature range, pressure, movement and installation location should be clearly defined. This is followed by the selection of the suitable material. For demanding applications, it is also advisable to check tolerances, service life and manufacturing processes.
Our rubber sheets
For industry and trade, we offer a wide variety of rubber sheets.
SBR rubber sheet
Our high-quality SBR rubber sheet (styrene-butadiene rubber) is the solution for numerous industrial and commercial applications. This rubber sheet is manufactured from first-class styrene-butadiene rubber and is characterised by its outstanding physical properties.
EPDM rubber sheet
Discover the versatility and reliability of our EPDM rubber sheet, which is manufactured from ethylene propylene diene monomer (EPDM). This high-quality elastomer solution has been specially developed to meet the most demanding industrial and commercial applications.
NBR rubber sheet
The NBR rubber sheet is a high-quality industrial product that has been specially developed for applications where excellent resistance to oils, greases and various chemicals is required.
Viton rubber sheet
The Viton rubber sheet is a high-quality technical product that is used for a wide range of industrial applications. Manufactured from fluoro rubber (FKM), it offers outstanding properties that make it the ideal choice for extreme conditions.
FKM rubber sheet
The FKM rubber sheet is a high-quality technical product that is ideal for use in demanding industrial applications. Made from fluoro rubber (FKM), it is characterised by a wide range of outstanding properties that make it the optimal choice for extreme operating conditions.
Silicone rubber sheet
The silicone rubber sheet is a first-class technical product that has been specially developed for applications that place high demands on temperature resistance and flexibility.
PUR rubber sheet
The PUR rubber sheet, made from high-quality polyurethane, is a technically advanced product that has been developed for applications that place the highest demands on abrasion resistance and mechanical load capacity.
Neoprene rubber sheet
The Neoprene rubber sheet, manufactured from high-quality chloroprene rubber (CR), is a versatile technical product that is ideal for a wide range of industrial and commercial applications.
