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Which seal suits your application? Materials, areas of use and clear decision-making guidance for mechanical engineering. Find out more now.
The selection of the right seal in mechanical engineering directly influences the sealing performance, service life and operational reliability of your systems. In practice, it becomes clear that failures rarely have complex causes. The origin often lies in a material choice that does not match the real load, or in a design that considers individual influencing factors in isolation. A seal only fulfils its task reliably when material, geometry and operating conditions are considered as a unit.
This guide is aimed at designers, buyers and technical decision-makers who are facing a specific selection and want to make a sound decision.
Understanding requirements in mechanical engineering
Seals separate media, hold pressure and protect components from external influences. In mechanical engineering, this results in combined load scenarios. This is precisely where the actual challenge lies.
Pressure rarely acts constantly. In hydraulic systems, loads rise sharply within a short time, while in other applications only low differential pressures are present. The decisive question is whether a seal seals statically or whether movements occur. Dynamic applications increase friction, temperature and wear.
Temperature directly influences the material structure. Elastomers change their properties depending on the temperature range. At low temperatures, hardness increases; at high temperatures, dimensional stability decreases. Typical ranges for NBR are roughly between −30 and +100 °C, EPDM often covers −40 to +120 °C, while FKM and PTFE reach significantly higher ranges.
The medium determines the chemical load. Oils, fuels, water, steam or aggressive chemicals affect materials differently. A seal can appear mechanically stable and yet fail quickly due to chemical influences.
In addition, external factors such as UV radiation, ozone or abrasion have an effect. Particularly in open machines or outdoor applications, this creates requirements that are often given too little consideration in planning.
Standards provide an important basis for design. DIN 3771 and ISO 3601 define O-ring geometries, DIN 2690 describes flat gaskets. For applications in sensitive areas, additional specifications such as FDA or EU 1935/2004 apply. These standards structure the design and create comparability.
Overview of seal types
The design of a seal determines how forces are absorbed and distributed. Different geometries react differently to loads.
Flat gaskets
Flat gaskets are used wherever two flat surfaces are sealed against each other. They offer a high degree of adaptability through material and thickness. In practice, they are found in housings, flanges and covers.
The function is created by surface pressure. An even distribution of force ensures reliable sealing. Material and thickness influence how well unevenness is compensated for.
O-rings
O-rings are among the most efficient sealing elements in mechanical engineering. Their round geometry enables even deformation in the groove. This creates a very reliable seal with a small installation space.
The design is based on defined standard series. Groove geometry, tolerances and compression influence the sealing effect. Particularly in hydraulics and pneumatics, O-rings have become established as standard.
Profile seals
Profile seals offer advantages in applications where movements or changing loads occur. Their geometry enables targeted absorption of forces and better adaptation to dynamic conditions.
In complex installation situations, they increase service life and ensure a more stable sealing effect.
Moulded parts and special seals
In mechanical engineering, requirements frequently arise that are not covered by standard geometries. Individual seals enable exact adaptation to installation space, load and function.
Materials in comparison
The material choice determines how long a seal fulfils its function. While the design forms the mechanical basis, the material determines resistance to temperature, media and load.
Which material for which application?
| Application | Recommended material | Reason |
|---|---|---|
| Hydraulics | NBR / FKM | oil-resistant and pressure-stable |
| Outdoor area | EPDM | UV- and weather-resistant |
| Chemical applications | PTFE | high chemical resistance |
| Food technology | Silicone / EPDM | hygienic and temperature-stable |
Material data at a glance
| Material | Temperature range (typ.) | Strengths | Notes |
|---|---|---|---|
| NBR | −30 to +100 °C | oil and fuel resistance | limited ozone resistance |
| EPDM | −40 to +120 °C | water, steam, UV/ozone | unsuitable for oil |
| FKM | −20 to +200 °C | high temperature and chemical resistance | higher price |
| PTFE | −200 to +260 °C | very high chemical resistance | low elasticity |
| Silicone | −60 to +200 °C | flexible and temperature-stable | lower mechanical load capacity |
In practice, the combination of medium, temperature and mechanical load determines the right choice.
How to select the right seal
A sound selection follows a clear sequence. First comes the analysis of the application. From this follows the material choice. Then the suitable design is defined.
The right seal in 3 steps
- Describe the application fully
- Check material compatibility
- Define geometry and installation situation
Once the requirements have been recorded cleanly, a clear decision-making basis is created.
Technical details: Shore hardness, compression, tolerances
The performance of a seal results from technical parameters.
Shore hardness describes the elasticity of the material. Lower values enable better adaptation, higher values increase dimensional stability.
Compression provides the actual sealing. Sufficient compression ensures that media are reliably separated.
Tolerances have a decisive influence on function. Particularly with O-rings, the exact matching of groove and seal determines service life.
Practical examples
In hydraulic systems, the focus is on the combination of pressure and oil resistance. NBR often forms the basis here, while FKM is used at higher temperatures.
Outdoor machines require resistance to weather influences. EPDM has proven itself in these applications.
In chemical plants, aggressive media are the focus. PTFE offers high resistance and stable properties here.
Typical applications in mechanical engineering
- Hydraulic systems with high pressure requirements
- Pneumatic systems with fast movements
- Systems in food technology
- Machines in outdoor areas
- Chemical processes with aggressive media
- Housings and covers with static sealing
Common mistakes in selection
- Material is chosen without media testing
- Temperature ranges are defined too narrowly
- Movements are not taken into account
- Pressure loads are underestimated
- Tolerances are designed too generously
- Service life requirements are missing from planning
What information you need for an enquiry
For a precise design, the following information should be available:
- Medium
- Temperature range
- Pressure conditions
- Installation situation
- Dimensions
- Quantity
When standard is enough – and when custom solutions make sense
Standard seals reliably fulfil a large proportion of all applications in mechanical engineering. They are based on standardised geometries, proven materials and clearly defined application limits. As soon as the boundary conditions lie within these limits, standard solutions offer an economical, quickly available and technically stable option.
Typical scenarios for standard solutions are applications with known media, moderate temperatures and clearly defined pressure conditions. Standard seals can also be used efficiently for static sealing or established designs, as they are based on proven designs.
Custom solutions gain in importance as soon as several loads occur simultaneously or the installation situation deviates from the standard. This applies in particular to applications with changing temperatures, aggressive media or dynamic movements. In such cases, the mere selection of a material is not enough – rather, the seal must be considered as part of the overall system.
In practice, it becomes clear that early coordination often brings the greatest added value. The more precisely the requirements are recorded, the more specifically it can be decided whether a standard solution is sufficient or whether an individual seal represents the better choice in the long term.
In conclusion
The selection of the right seal in mechanical engineering is always the result of a systematic consideration of the application. Evaluating individual factors in isolation frequently leads to problems in practice. Only the interaction of medium, temperature, pressure, movement and geometry provides a sound decision-making basis.
In many cases, reliable results can be achieved with standard solutions, as long as the operating conditions are clearly defined and lie within proven limits. However, as soon as several loads occur simultaneously or the installation situation deviates from standard geometries, the demands on material and design increase significantly.
Particularly in mechanical engineering, it becomes clear that the quality of the seal not only influences the function of individual components, but the entire operational reliability and service life of a system. A precise selection reduces failure risks, extends maintenance intervals and ensures stable processes.
If you are facing a specific application, a structured assessment of all influencing factors is recommended. On this basis, it can quickly be determined whether a standard solution is sufficient or whether an individually designed seal represents the better choice in the long term.
Send us the technical requirements and receive a tailored recommendation including material choice and cut to size, matched to your specific application.
Frequently asked questions
Which seal is suitable for high pressures?
For applications with high pressures, NBR or FKM seals are often suitable. Which solution fits also depends on temperature, medium and installation situation.
Which material is suitable for chemical applications?
PTFE is often used for chemically demanding applications, as the material has a high resistance to many aggressive media.
When is EPDM the right choice?
EPDM is particularly suitable for applications with water, steam, UV radiation, ozone or weather influences. In outdoor areas, this material is often a very suitable solution.
When should a custom solution be chosen instead of a standard seal?
A custom solution is advisable when several loads occur simultaneously, the geometry deviates from the standard or there are high requirements for service life and operational reliability.
What role does Shore hardness play in seals?
Shore hardness describes the elasticity of the material. It influences how well a seal adapts and how dimensionally stable it remains under load.
What information is useful for an enquiry?
Information on medium, temperature range, pressure conditions, installation situation, dimensions and quantity is helpful. The more precisely the data is available, the more precisely the right seal can be selected.
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.
