Gehäusedichtungen werden benötigt, um das Innere eines Gehäuses vor äußeren Einflüssen wie Staub, Wasser, Chemikalien und anderen Verunreinigungen zu schützen. Sie sorgen für eine dichte Abdichtung, die unerlässlich ist, um die Langlebigkeit und Funktionalität der im Gehäuse befindlichen Komponenten zu gewährleisten.

The sealing of a Industrial housing rarely receives much attention – yet it is almost always one of the most critical. It determines whether electronics operate reliably under continuous use, whether a sensor maintains its specified accuracy over years, and whether a device receives approval for a regulated market. If the seal fails, the entire system typically fails – often gradually, often only recognised late and usually expensively.

Modern housings are sealed against a wide range of influences: dust, splash and jet water, aggressive process media, gases, pressure and vacuum differences, biocontamination, vibrations and electromagnetic radiation. Depending on the field of application, the requirements range from simple dust protection to IP69 tightness, with simultaneous EMC protection and sterilisation capability.

Gehäuse und Gehäusedichtungen finden in einer Vielzahl von Branchen Anwendung, darunter: * **Automobilindustrie:** Zum Schutz von Motorkomponenten, Elektronik, Beleuchtung und anderen Teilen im Fahrzeug. * **Elektronik und Elektrotechnik:** Für Computergehäuse, Schaltkästen, Steckverbinder und empfindliche elektronische Bauteile. * **Industrielle Automatisierung und Maschinenbau:** Zum Schutz von Sensoren, Aktuatoren, Steuerungen und Bedienoberflächen in Fertigungsanlagen. * **Medizintechnik:** Für medizinische Geräte, Instrumente und implantierbare Komponenten, wo Sterilität und Schutz vor Kontamination entscheidend sind. * **Luft- und Raumfahrt:** Zum Schutz von Avionik, Sensoren und anderen kritischen Systemen unter extremen Bedingungen. * **Marine- und Offshore-Industrie:** Zum Schutz von Geräten vor Salzwasser, Feuchtigkeit und Korrosion. * **Energieerzeugung und -verteilung:** Für Umspannwerke, Windkraftanlagen, Solarmodule und andere Energieinfrastruktur. * **Telekommunikation:** Für Antennen, Basisstationen und Netzwerkausrüstung. * **Bauwesen:** Für Beleuchtungskörper im Freien, elektrische Schalter und Steuereinheiten. * **Verkehrswesen:** Für Signaltechnik, Fahrkartenautomaten und Sicherheitsausrüstung. Im Wesentlichen werden Gehäuse und Gehäusedichtungen überall dort eingesetzt, wo empfindliche Komponenten vor Umwelteinflüssen wie Staub, Wasser, Feuchtigkeit, Chemikalien, extremen Temperaturen, Stößen oder Vibrationen geschützt werden müssen.

Which sealing method is technically and economically sensible depends on the respective field of application. In typical high-tech industries, priorities vary significantly.

In the Medical Technology Sterilisability and biocompatibility are dominant. Housings must withstand autoclave cycles (mostly 134 °C at 3 bar steam), low-temperature sterilisation with H₂O₂ or ethylene oxide, and aggressive surface disinfectants. Seals must neither leach nor age significantly. Cleanable geometries without grooves or undercuts are mandatory.

In Semiconductor and cleanroom environment Particle poverty and low outgassing are paramount. Elastomers must be chemically resistant to process gases, acids, solvents, and plasma environments. High-performance sealing materials are standard here; contamination by fillers, plasticisers, or release agents from seal manufacturing are a deal-breaker.

In the Aerospace require solutions adapted to extreme temperature ranges from below -65°C to above +200°C, vibrations, alternating pressure loads, and weight restrictions. In addition, there is a strict batch traceability of materials and the requirement for reproducible, validated manufacturing processes.

In the Electronics – from industrial electronics to power electronics, e-mobility and telecommunications – tight installation spaces meet high thermal loads and demanding environmental conditions. Enclosures must reliably keep out moisture, condensation, and corrosive gases without compromising heat dissipation. Outgassing sealing components are critical because they can lead to fogging or corrosion on contacts and optical surfaces. In addition, there is almost always an EMC requirement, which is solved using conductive elastomer compounds (nickel-graphite, silver, carbon) – regardless of the mounting method chosen. High volumes and short product life cycles make the reproducibility and automability of the sealing process key economic factors.

In Mechanical Engineering as well as in sensory and measurement technology The design is determined by IP protection classes up to IP69K, media resistance, reproducibility in series production, and long-term stability. EMC requirements are also frequently relevant here and are addressed via the compound.

From these requirements, typical material choices for the elastomeric seal arise: EPDM for water and steam applications, NBR for oils, FKM (Viton) for chemicals and heat, and silicone for biocompatibility and wide temperature ranges.

7 different housing seals

Housing seals can be designed very differently depending on the application – from simple O-rings and stamped flat seals to permanently vulcanised seals. Which variant is suitable depends on the geometry, the quantity, the assembly process, the sealing requirements and the desired process reliability.

1. O-ring in nut

The O-ring It is the best-known and most widely standardised sealing element of all. It consists of a ring-shaped elastomer profile with a circular cross-section, which is inserted into a groove and sealed against a mating surface by compression. Typical compression ratios range from 15–30 % of the cord diameter.

Figure 1: Example O-ring

O-ring properties, such as compression set, Shore hardness, compression set, and media resistance, determine their function and application. Material and geometry can be chosen independently, making the variant technically extremely flexible.

Advantages:

• High standardisation (ISO 3601) and worldwide availability
• A very wide range of materials across all common elastomer families
• Low component costs even in small quantities
• Suitable for both static and dynamic applications
• Simple spare parts management and tolerant handling during service

Disadvantages:

• Nut geometry must be precisely executed – edge quality and roughness are critical for density
• Loose component: may be overlooked, twisted or jammed during assembly
• Only suitable for circular or convex contours
• Risk of spiral twisting in dynamic applications subject to vibration

Typical application: screwed covers and flanges in sensor technology, hydraulics, pneumatics, and general mechanical engineering.

2. Stamped flat gasket

The stamped flat gasket is the classic solution for large-area, non-circular sealing contours. It is cut from coil stock or sheets using stamping, waterjet, or laser processes and placed loosely between two parallel flanges. Sealing is achieved over the entire surface by defined compression using screw force.

Figure 2: Stamped flat gasket

The sealing rubber is a two-dimensional semi-finished product here: it has a constant thickness and a contour that can be freely chosen in the plane, but no three-dimensional functional geometry. Materials range from elastomer sheets (EPDM, NBR, FKM, Silicone) through to fibre and cork-rubber combinations.

Advantages:

• Any flat contours are achievable without tooling investment
• Very low entry costs, ideal for prototypes and small production runs
• Short lead times, as no mould-making is required
• Accommodates larger flange dimensions and flatness deviations
• It is possible to change materials easily within the same geometry

Disadvantages:

• No integrated features such as crimping stops, centering noses or multi-chamber profiles
• A constant thickness necessitates compromises in terms of contact force
• Loose part with typical assembly errors (slipping, doubling, missing)
• With soft materials, there's a risk of extrusion into the sealing gap.
• Less reproducible than injection-moulded profiles

Typical applications: Control cabinets, terminal boxes, large-scale covers on machine frames, standard enclosures with rectangular flanges.

3. Injection-moulded or compression-moulded seal

Where flat seals reach their geometric limits, custom-moulded seals built directly in the tool come into play. They are manufactured to customer specifications in the Rubber injection moulding  or in Formpressverfahren Manufactured and can be freely designed in three dimensions. The seal is therefore no longer created from a semi-finished product, but is produced in a metal tool specially made for this seal.

Figure 3: Example special geometry seal

The moulded seal usually performs significantly more functions than just sealing: it can incorporate sealing lips, compression stops, centering nubs, multi-chamber profiles, different materials in a single component (2K) or integrated functional areas such as membranes and grommets. Since the moulded seal is always custom-made, there is maximum design freedom regarding the seal geometry and its integration with the housing.

Advantages:

• Fully custom 3D geometry, adapted to the casing
• Integration of multiple functions (sealing lip, stopper, centering, grommet) in one part
• Very good reproducibility and tight tolerances (tool accuracy)
• Defined crimping by integrated stops – screw force-independent
• High surface quality, also suitable for visible and cleaning surfaces
• Combinable with multi-component processes (hard carrier + soft sealing lip)

Disadvantages:

• Tool investment required – only economically viable for medium production runs.
• Short development phase required
• The seal remains a loose component with an assembly risk.
• Geometry can only be adapted after tool creation at an additional cost.

Typical application: High-quality electronic enclosures, sensor technology, measuring technology, control units, enclosures with complex parting surfaces or integrated controls.

4. FIPG / CIPG – Liquid applied sealing beads

Formed-in-Place Gaskets (FIPG) and Cured-in-Place Gaskets (CIPG) summarise processes where a bead of pasty silicone or polyurethane sealant is applied directly onto one of the mating surfaces. With FIPG, the parts are assembled while the material is still liquid; the material cures in the joint. With CIPG, the bead is first cured on one component and the mating part is then bolted on – similar to a conventional gasket.

The sealing rubber is not a pre-fabricated component here, but is created at the location of its function. The bead adapts to the actual joining geometry, compensates for flatness deviations, and, after curing, is firmly connected to one of the two surfaces. The material is typically a 1K or 2K silicone with a defined Shore hardness and defined flow behaviour.

Advantages:

• No loose sealing parts, no parts logistics on the sealing side
• Very good adaptation to real manufacturing tolerances and flange distortion
• Any contours without your own sealing tool
• High degree of automation with 3D dispensing robots
• Rapid geometry changes via CAD update without tooling intervention

Disadvantages:

• Investment in dosing equipment and strict process control required
• Limited dismantling and reuse (especially FIPG)
• Compression set typically worse than with moulded elastomers
• Temperature and media resistance limited to available dispenser materials
• Curing time affects the production rate

Typical applications: Automotive control units, sensor housings in medium to high volumes, small electronic components for mechanical engineering.

5. Bonding with sealing function

In structural bonding, a separate seal is completely dispensed with; instead, an adhesive – typically a 2K-Polyurethane, a modified silane polymer or an epoxy – simultaneously fulfilling the joining and sealing functions. The process permanently and adhesively bonds two housing parts; the screw connection is eliminated or is only needed for pure fixation during curing.

A sealing rubber in the classical sense does not exist here. The elastic component is inherent in the adhesive itself: after curing, it must retain sufficient elasticity to absorb thermal expansion between aluminium, plastic and circuit board carriers without tearing.

Advantages:

• No separate seal, no screws, no groove milling
• Large-area voltage distribution and high vibration robustness
• Additional stiffening of the housing by bonding
• Hermetically sealed joints with high IP protection possible
• Reduced part count and fewer manufacturing steps

Disadvantages:

• Practically irreversible – service and repair excluded
• Surface pre-treatment (cleaning, plasma, primer) is process-critical
• Curing times affect the cycle time and require clamping fixtures.
• Additional assembly step
• Long-term stability strongly depends on the adhesive-substrate pair
• Qualification per material combination is complex

Typical applications: bonded electronic housings in consumer and industrial electronics, hermetically sealed sensors, potted housings.

6. Material-positive joining without elastomer

This category covers all processes in which two housing halves are directly fused or welded together – without sealing elements and without adhesive. For plastic housings, ultrasonic, vibration, hot gas, and laser beam welding are established. For metal housings, laser welding, electron beam welding, or shielding gas processes (TIG/MIG) perform the same function.

The component has no independent seal: the sealing gap is reduced to zero as the joining partners become a single material. Sealing rubber no longer plays a role in this variant – unless individual penetrations such as connectors, cables or Membranes are sealed separately.

Advantages:

• Technically highest achievable density
• No ageing sealing component, no compression set
• Very slim designs and small construction volumes possible
• Long-term stability over product life cycles of decades
• No media source, no compatibility check seal/medium necessary

Disadvantages:

• Non-dismantlable – Service and maintenance excluded
• Material combinations strongly restricted (usually like with like)
• Distortion and residual stresses as process-related challenges
• Extensive qualification per product variant
• High demands on upstream component quality (joint gap, cleanliness)
• Elaborate joining process

Typical applications: implantable medical technology, hermetic sensors, transponders, high-reliability electronics in aerospace.

7. Vulcanised seal

In the case of vulcanised sealing, the elastomer is applied to the housing in a material bond during cross-linking. The housing, made of plastic or metal, is inserted as a component into the individual mould. Rubber is injected under pressure and temperature into the sealing contour and vulcanises directly onto the prepared surface. The result is an inseparable, material bond between the substrate as Rubber-metal connection or rather Rubber-plastic connection.

Figure 4: Housing with vulcanised gasket

The process works for both metal housings (aluminium, stainless steel, brass – typically with adhesion promoter/primer) and plastic housings (PA, (PBT, PPS, PC, etc.). The sealing rubber is not a separate part here that needs to be inserted, glued, or mounted individually, but rather an integral component of the housing.

Advantages:

• Seals must not be forgotten, twisted or damaged during assembly
• High-precision positioning accuracy
• No separate assembly – „housing plus seal plus process step“ becomes a single part
• Highest reproducibility, ideal for validated processes (medicine, aerospace, semiconductors)
• Fabric-based connections allow for filigree geometries and very small sealing cross-sections
• Maximum design freedom
• Reduced number of parts, lower logistics and testing effort
• Free scaling via component selection (Media, Printing, EMC, Sterilisation)
• Top quality in terms of tightness, reproducibility and process reliability.

Disadvantages:

• Tool manufacturing with additional costs necessary
• The development phases for the substrate, adhesive system, and compound must be coordinated.
• Seal not replaceable separately – entire component must be replaced if damaged

Typical applications: high-quality sensor and measuring technology housings, medical technology assemblies, semiconductor handling technology, aerospace electronics – everywhere where the highest quality, reproducibility and process reliability are required.

The 7 sealing methods in direct comparison

The following table compares the seven processes based on the most important technical and economic criteria. The ratings should be understood as guidelines – the specific outcome depends on the material selection, geometry, and process control in each individual case.

Criterion	O-ring	Flat gasket (Punched)	Mould gasket Tool	FIPG / CIPG	Sealing adhesive	Welding	Vulcanised
Leakproofness	High	medium	High	High	High	very high (hermetic)	very high
Reproduce capability in Serie	medium	slight to medium	High	High	medium	High	very high
Assembly effort	medium	medium to High	medium	slight	High Adhesive bonding process	High (Welding required)	cancelled integrated
Disassembly	Gut	Gut	Gut	limited	Not possible	Not possible	Gut (as a component)
Tool costs	slight	very low	High	slight	slight	medium	High
Cost per unit in Serie	slight	slight	medium	medium	medium	medium	medium
Geometric Flexibility	slight run	medium (2D only)	very high (3D)	very high	very high	High	very high

Which sealing system is suitable for which application?

In practice, the choice of sealing method is not primarily dictated by the quantity produced – almost all the methods described here are used in both small-batch production and for millions of units. Four criteria are crucial: housing geometry, the requirements profile, service concept, and economic viability.

Criterion 1: Housing geometry and seal contour

The joint geometry already excludes many variants by itself:

• Round, rotationally symmetrical sealing surfaces (screw fittings, cylindrical lids, threaded seals) are the natural domain of the O-ring – here it is also technically and economically unbeatable in the highest of quantities.
• Flat, large-area flanges with a simple contour are typically sealed with a cut flat gasket.
• Complex 3D seal contours with integrated features (seal lips, stoppers, spigots) require a tool-bound mould seal, FIPG/CIPG, or a pre-vulcanised seal.
• Lost or very small construction spaces without a flange design suggest sealant bonding or welding.

Criterion 2: Requirements Profile

Irrespective of the geometry, there are hard technical exclusion criteria:

• When hermetic sealing is required, welding (of both plastics and metals) is the preferred alternative.
• Where the highest reproducibility and process reliability are required (validated manufacturing in medical technology, semiconductors, aviation, high-end electronics), the pre-vulcanised gasket is the benchmark, as it saves an assembly step, is firmly integrated into the housing, and thus eliminates the dominant source of error.
• Whether aggressive media, extreme temperatures or sterilisation are the focus, the choice of compound (FKM, HNBR, Silicone) is less important than the sealing system. Practically all classic methods (O-ring, moulded seal, vulcanisation) are compatible, while FIPG/CIPG and seal bonding reach their limits earlier in terms of material properties.
• If space is tight – which is typical in miniaturised electronics and sensor technology – vulcanised-on seals show their strengths because they do not require a flange or groove geometry.

Criterion 3: Service Concept and Lifecycle

The question of whether an enclosure should ever be opened again is at least as important as the seal itself when making a selection:

• Service-friendly products with planned opening (maintenance, battery replacement, calibration, cleaning) exclude welding and adhesive bonding. This leaves O-rings, flat or shaped seals, FIPG/CIPG, and vulcanised-in seals – the latter with the advantage that the seal reliably remains on the housing even after repeated opening.
• Maintenance-free, lost housings (disposable products, sealed sensors, high-reliability electronics) conversely benefit precisely from welding or adhesive bonding, because the elimination of an elastomer-side ageing component maximises the service life.
• Products with high assembly automation – whether small or large series – favour processes that avoid the insertion of a sealing component: FIPG/CIPG, adhesive sealing and, in particular, the vulcanised-in seal, where the seal is already physically part of the housing.

Criterion 4: Economic Viability

Only once the three technical axes have narrowed down the selection does economic efficiency come into play. It's not the process itself that is expensive or cheap, but the overall system comprising the component, assembly, testing, and scrap. An O-ring costs a few pence but can cause significant follow-on costs in automated assembly due to incorrect positioning. A vulcanised seal incurs higher tooling and component costs, but makes assembly, commissioning, and an entire testing step unnecessary. Which calculation is successful is decided on a project-specific basis – and should always be considered over the entire Total Cost of Ownership, not over the unit price of the seal.

Conclusion

Seven established methods are available today for sealing an industrial enclosure, from the standardised O-ring to the hermetically welded capsule. Each variant has its justification, its economic sweet spots, and its technical limitations.

The vulcanised seal holds a special position in this field: it combines the geometric freedom of tool-bound moulded seals, the process reliability of injection moulding, and the resistance of highly cross-linked elastomers with the crucial advantage that the seal becomes a physical part of the housing. Inserts, no assembly errors, no positional drift, no logistics for an additional part, and no assembly after the housing has been manufactured. For industries where validated processes, consistent quality, and the highest reliability are crucial – medical technology, semiconductors, aerospace, sensor technology, and measurement technology – it is the benchmark solution among housing seals.

Ultimately, the right variant for a specific project is decided at the intersection of the requirements profile, production volume, and product lifecycle, and should be determined as early as possible in product development, as the sealing concept and housing design are closely linked.