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Flat gaskets made of rubber in NBR, EPDM, FKM & silicone. Find out all about applications, selection criteria and custom-made parts.
Rubber sheets play a central role in electrical insulation in industrial practice. They are used wherever electrical energy is controlled and reliably shielded at the same time. In control cabinets, power systems and machines, this creates a safe separation between live and touchable areas. This reduces the risk of flashovers, leakage currents and unwanted dissipation, while at the same time increasing operational safety.
As power densities rise and designs become more compact, the demands on materials increase significantly. Components are positioned closer together, thermal loads rise and ambient conditions become more complex. Rubber sheets combine electrical insulation with mechanical stability and can be flexibly adapted to different installation situations. A clean design of material, thickness and installation situation ensures long-term operational safety and reduces maintenance effort and downtime.
Fundamentals of electrical insulation with rubber
Rubber acts as an electrical insulator because its polymer chains allow hardly any freely moving charge carriers. Electrical energy is therefore bound within the material instead of spreading as a current flow. In practice, however, it is less the pure material property that decides than the interaction of field strength, material thickness, surface condition and ambient conditions.
When voltage is applied, an electric field forms across the material thickness. As field strength rises, the load increases until, in the limiting case, a breakdown occurs. This process depends heavily on the homogeneity of the material, on inclusions and on the quality of the surface. Smooth, clean surfaces reduce local field peaks and increase stability.
Moisture, dust and chemical residues additionally influence surface conductivity. In industrial environments, this creates leakage currents along the surface, which shorten the effective insulation distance. A clean design with sufficient clearances and suitable materials ensures stable conditions.
Temperature also has a direct effect on insulation. As temperature rises, the mobility of the molecular chains increases, which changes electrical properties. Materials such as silicone retain their properties over a broad temperature range, while other elastomers react more strongly to temperature. A robust design takes these effects into account already in the planning phase.
Key parameters at a glance
| Parameter | Typical values | Meaning |
|---|---|---|
| Dielectric strength | 10–30 kV/mm | maximum electrical load |
| Volume resistivity | 10¹³ – 10¹⁶ Ohm cm | insulation quality within the material |
| Surface resistivity | 10¹² – 10¹⁵ Ohm | behaviour on contact |
| Temperature range | -30 to +200 °C | application limits |
In practice, safety reserves are used, since real conditions rarely remain constant. Load peaks, moisture or contamination can increase the electrical load locally. A conservative design ensures that the insulation remains stable even under unfavourable conditions.
Which types of rubber are suitable
| Material | Dielectric strength | Temperature | Special feature |
|---|---|---|---|
| EPDM | approx. 20–30 kV/mm | -40 to +120 °C | stable insulation, UV- and weather-resistant |
| Silicone | approx. 20–25 kV/mm | -60 to +200 °C | high temperature stability |
| NBR | approx. 10–20 kV/mm | -30 to +100 °C | resistant to oils and greases |
| SBR | approx. 10–15 kV/mm | -20 to +80 °C | economical for standard applications |
The choice of material depends on the environment, temperature profile and mechanical load. EPDM is suitable for outdoor areas and changing weather, silicone for high temperatures and sensitive applications. NBR is used specifically in oil-loaded environments, while SBR is often used in less critical applications.
Decision aid for practice
| Situation | Recommendation |
|---|---|
| dry control cabinet | EPDM 3–5 mm |
| oil-containing environment | NBR 5–8 mm |
| outdoor area with UV influence | EPDM 5–10 mm |
| high temperatures | silicone project-specific |
In addition to these basic parameters, the installation situation, surface pressure and maintenance intervals play a role. Large contact surfaces require uniform material thicknesses, while point loads make higher reserves necessary.
Voltage and material thickness
| Voltage | recommended thickness |
|---|---|
| up to 1 kV | 2–3 mm |
| up to 10 kV | 5–8 mm |
| over 10 kV | project-specific |
As voltage rises, the need for material thickness and safety clearance grows. In high-voltage applications, additional design measures such as clearances, covers or multilayer systems are used to secure the insulation permanently.
Insulating, antistatic, conductive
Insulating materials prevent current flow and serve personal protection as well as the separation of electrical areas. Antistatic materials dissipate electrical charge in a controlled manner and are used above all in sensitive production environments. Conductive materials enable targeted dissipation of charge. For classic insulation tasks, exclusively insulating material is used, since even low conductivity reduces the protective effect.
Typical areas of application
- Control cabinet construction and distribution systems
- Mechanical engineering and plant construction
- Power and high-voltage areas
- Test benches and laboratory environments
Practical examples
In the control cabinet, the rubber sheet acts as an insulating base between components and housing, thereby avoiding unwanted contact points. In mechanical engineering, it serves as a separating layer between conductive components and at the same time reduces mechanical vibrations. In power systems, defined working areas are secured so that operating personnel find clearly demarcated and safe zones.
Processing and installation
Processing decisively determines the actual performance of the rubber sheet in operation. Proper preparation begins with a level, load-bearing substrate. Unevenness leads to local pressure peaks and uneven field distribution, which increases the electrical load at specific points.
The sheet is laid over the full surface so that a closed contact area is created. Even small cavities or air pockets can change the field distribution and favour unwanted effects. Stress-free laying ensures that the material adapts evenly and no internal stresses arise that would lead to material fatigue in the long term.
When fastening, suitable methods must be used that neither damage the material nor overload it at specific points. Mechanical fixings are designed so that they support the surface evenly. In areas with movement or vibration, elastic mounting provides additional stability.
Particular attention is paid to edges and transitions. Clean, even cut edges prevent field concentrations and reduce the risk of leakage currents. Transitions to other materials are designed so that no abrupt material changes with strongly differing properties occur.
Service life and maintenance
The service life of rubber sheets depends on a large number of influencing factors. Mechanical load, temperature changes, UV radiation and chemical effects change the material structure over time. Elastomers react to this with hardening, loss of elasticity or fine cracking.
A structured maintenance approach includes regular visual inspections as well as an assessment of the operating conditions. Areas with high load or direct exposure to media are checked at shorter intervals. Changes to the surface and structure serve as indicators of the condition of the insulation.
Operating data also play a role. High load cycles, frequent temperature cycles or aggressive media shorten the service life. Forward-looking planning takes these factors into account and defines replacement cycles based on real operating conditions.
Consistent maintenance keeps the insulating effect stable and reduces unplanned failures. The timely replacement of worn sheets contributes to long-term operational safety.
Avoiding typical mistakes
- unsuitable material for the environment
- insufficient material thickness
- incomplete coverage of contact surfaces
- mechanical damage during installation or operation
Safety requirements and standards
- DIN EN 61111 for insulating mats
- IEC guidelines for electrical installations
- VDE specifications for safe operation
Standards define test methods, minimum values and areas of application. They serve as a basis for the design and ensure that materials and applications meet the technical requirements.
Cut to size and application in practice
The cut to size directly influences the function of the rubber sheet. Exact dimensions ensure complete coverage of the relevant areas and avoid open edges or transitions. Even small dimensional deviations lead to contact surfaces being loaded unevenly or gaps forming.
Modern manufacturing processes enable precise cut pieces even with complex geometries. Contours, recesses and feed-throughs can be adapted exactly to the respective application. This creates a precisely fitting integration into existing systems that functions reliably both mechanically and electrically.
The quality of the cut edges plays a central role. Smooth, clean edges reduce field concentrations and ensure an even distribution of the electrical load. Post-processing such as deburring or edge rounding further improves the properties.
In application, the cut piece is chosen so that it supports assembly and maintenance. Replaceable segments, modular surfaces or defined interfaces facilitate handling during ongoing operation. A well-considered design of the cut piece thus contributes directly to the efficiency and safety of the entire system.
Frequently asked questions
Which rubber sheet is suitable for electrical insulation?
For most applications, EPDM and silicone are used. EPDM is suitable for outdoor areas and general industrial applications, while silicone is used at high temperatures and in sensitive electrical applications. The selection always depends on voltage, environment and mechanical load.
How high is the dielectric strength of rubber sheets?
Depending on the material, the dielectric strength is generally between 10 and 30 kV per millimetre. High-quality materials such as EPDM or silicone achieve stable values in the upper range, while simpler compounds have lower values.
What thickness should a rubber sheet for insulation have?
The required thickness depends directly on the voltage applied. For low voltages, 2 to 3 mm is often sufficient, while for higher voltages 5 to 10 mm or more are required. For critical applications, the design is project-specific.
What is the difference between insulating and antistatic rubber?
Insulating rubber completely prevents current flow and serves to protect people and systems. Antistatic rubber dissipates electrical charges in a controlled manner and is used above all in sensitive production areas. For classic insulation, exclusively insulating material is suitable.
How long do rubber sheets last in use?
The service life depends on load, temperature, UV influence and chemical environment. In stable indoor areas, rubber sheets often last many years, while under strong environmental influences they age more quickly. Regular visual inspections help to determine the right replacement time.
How can worn rubber sheets be recognised?
Typical signs are cracks, hardening, discolouration or mechanical abrasion. Changes to the surface or elasticity also indicate material ageing and should be regarded as a reason for replacement.
Can rubber sheets be cut to size individually?
Yes, rubber sheets can be cut exactly to size. Individual cut pieces ensure complete coverage, clean edges and an even insulating effect, especially in complex installation situations.
Where are insulating rubber sheets typically used?
Typical areas of application are control cabinets, machines, power systems, test benches and workplaces with electrical hazards. They serve as bases, covers or separating layers.
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 distinguished 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 requiring excellent resistance to oils, greases and various chemicals.
Viton rubber sheet
The Viton rubber sheet is a high-quality technical product that is used for a wide variety 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 distinguished by a large number 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 placing high demands on temperature resistance and flexibility.
PUR rubber sheet
The PUR rubber sheet, manufactured from high-quality polyurethane, is a technically advanced product that has been developed for applications placing 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 variety of industrial and commercial applications.
