Automotive and transportation components operate in demanding environments. Temperature changes, sunlight, rain, vibration, road debris, oils, fuels, repeated movement, and years of environmental exposure can all affect the performance of rubber seals and profiles.
Custom rubber extrusions are widely used throughout vehicles and transportation equipment to provide sealing, cushioning, vibration isolation, edge protection, and environmental protection.
From weatherstripping and door seals to tubing and complex custom profiles, the correct combination of material and extrusion design can have a significant impact on long-term performance.
Northwest Rubber Extruders (NWRE) manufactures custom rubber extrusions and custom silicone extrusions for OEM and industrial applications.
This guide explores common automotive and transportation applications, material considerations, and factors to evaluate when designing a custom rubber profile.
Where Are Rubber Extrusions Used in Vehicles?
Rubber extrusions can be found throughout automotive and transportation equipment.
Potential applications include:
- Door seals
- Window seals
- Weatherstripping
- Hatch seals
- Trunk seals
- Equipment compartment seals
- Protective edging
- Channels
- Tubing
- Gaskets
- Vibration-control components
- Bumpers
- Interior seals
- Exterior seals
- Custom protective profiles
Similar components are used beyond passenger vehicles in applications involving:
- Commercial trucks
- Trailers
- Buses
- Recreational vehicles
- Rail equipment
- Specialty vehicles
- Heavy equipment
- Transportation infrastructure
Each application may require different material and profile characteristics.
Why Rubber Is Important in Transportation Applications
Vehicles contain hundreds or thousands of components that experience constant movement.
Rubber provides several properties that make it useful in these environments.
Sealing
Rubber profiles can help create barriers against:
- Water
- Air
- Dust
- Dirt
- Road debris
Vibration Control
Flexible elastomers can help isolate components and reduce vibration transfer.
Cushioning
Rubber can provide a protective interface between rigid surfaces.
Noise Reduction
Properly designed seals can help reduce movement and unwanted noise between components.
Edge Protection
Rubber channels and profiles can protect exposed metal, glass, or other surfaces.
Flexibility
Rubber components can flex as doors, panels, hatches, and other vehicle components move.
These requirements help explain why elastomeric components are used extensively throughout transportation equipment.
EPDM Rubber Extrusions for Automotive Applications
EPDM is one of the most commonly considered materials for automotive weather-sealing applications.
It provides excellent resistance to:
- Ozone
- UV exposure
- Weather
- Water
- Environmental aging
These characteristics make EPDM particularly useful for components exposed to outdoor conditions.
Potential EPDM applications include:
- Door weatherstripping
- Window seals
- Hatch seals
- Trunk seals
- Exterior equipment seals
- Protective profiles
Vehicles may remain outdoors for years while experiencing sunlight, rain, snow, humidity, and major temperature changes.
A material used for exterior sealing needs to tolerate these conditions while maintaining useful physical properties.
This is one reason EPDM is frequently considered for automotive and transportation sealing applications.
Silicone Extrusions for Transportation Applications
Silicone may be considered when temperature performance becomes a major requirement.
Depending on the specific compound, silicone can provide:
- Excellent high-temperature performance
- Excellent low-temperature flexibility
- Excellent UV resistance
- Excellent ozone resistance
- Strong environmental aging characteristics
These properties can make custom silicone extrusions useful for specialized transportation components.
Silicone may be considered for applications near:
- High-temperature equipment
- Electrical components
- Lighting systems
- Engines
- Heating systems
- Specialized transportation equipment
The specific compound should always be evaluated against the operating environment.
Nitrile for Oil and Fuel Exposure
EPDM performs exceptionally well against weather, but it is generally not the preferred elastomer for regular exposure to petroleum-based oils and fuels.
For those environments, nitrile may be considered.
Nitrile rubber is commonly valued for its resistance to:
- Petroleum oils
- Fuels
- Lubricants
- Certain hydrocarbon-based fluids
This makes nitrile potentially useful for components located around machinery, engines, fuel systems, and other areas where petroleum exposure is expected.
Material selection should be based on the specific substance, concentration, temperature, and duration of exposure.
Automotive Weatherstripping
Weatherstripping is one of the most recognizable applications for rubber extrusion.
Vehicle weatherstripping helps create a seal around areas such as:
- Doors
- Windows
- Hatches
- Trunks
- Equipment compartments
- Access panels
The extrusion must maintain contact between mating surfaces while allowing doors and panels to open and close properly.
This requires careful consideration of:
- Material
- Durometer
- Profile geometry
- Compression
- Closing force
- Temperature
- Environmental exposure
A seal that is too difficult to compress can increase closing force.
A seal that doesn’t compress enough may not maintain sufficient contact.
Profile design is therefore critical.
D-Shaped Automotive Seals
D-shaped extrusions are commonly used for compression sealing.
The flat portion of the profile provides a mounting surface, while the rounded section compresses against another surface.
D-profiles can be manufactured as solid or hollow extrusions.
Hollow D-shaped seals generally compress more easily, which can make them useful around:
- Doors
- Hatches
- Equipment compartments
- Access panels
The dimensions of the profile can be customized around the available space and required compression.
P-Shaped Seals
P-shaped rubber profiles combine a sealing bulb with an extended mounting section.
This design can provide both a method of positioning the extrusion and a compressible sealing surface.
P-profiles may be used around:
- Doors
- Panels
- Compartments
- Vehicle bodies
- Transportation equipment
Custom dimensions allow the profile to be designed around the specific assembly.
Bulb Seals
Bulb seals are another common option for transportation applications.
The hollow bulb section compresses when two surfaces come together.
Because the profile contains an internal cavity, it can provide substantial compression without requiring the force that might be necessary with a solid rubber profile.
Bulb seals can be manufactured in different configurations, including:
- Round bulbs
- Oval bulbs
- Side bulbs
- Top bulbs
- Custom hollow shapes
The mounting portion can also be customized according to the installation method.
Rubber Channels and Edge Protection
U-channels and other rubber channel profiles can be used to protect edges or create a flexible interface between components.
Potential applications include:
- Sheet metal edges
- Glass edges
- Panels
- Equipment housings
- Interior components
- Vehicle bodies
Rubber edge profiles can help provide cushioning and reduce direct contact between rigid surfaces.
The channel dimensions should be designed around the thickness of the surface it needs to fit.
Rubber Tubing for Transportation Equipment
Rubber tubing can be manufactured through the extrusion process in a wide range of sizes.
Important dimensions include:
- Outside diameter
- Inside diameter
- Wall thickness
Tubing may be used for protection, insulation, sealing, cushioning, or other specialized purposes.
Material selection depends heavily on the environment.
For example, tubing exposed to outdoor weather may require different material properties than tubing exposed to petroleum fluids or elevated temperatures.
Solid vs. Hollow Vehicle Seals
Whether a profile should be solid or hollow depends on its function.
Solid Rubber Profiles
Solid extrusions may be appropriate for:
- Bumpers
- Protective strips
- Spacers
- Edge protection
- Wear surfaces
- Certain gaskets
They generally provide greater resistance to compression and deformation.
Hollow Rubber Profiles
Hollow extrusions are often useful for seals.
The internal cavity allows the profile to collapse under pressure, reducing the force required for compression.
Potential applications include:
- Door seals
- Hatch seals
- Trunk seals
- Compartment seals
- Equipment enclosures
Profile geometry can often be adjusted to achieve the desired compression characteristics.
Durometer and Vehicle Seal Performance
Durometer measures the hardness of rubber.
Selecting the correct durometer is important because it affects:
- Flexibility
- Compression
- Closing force
- Installation
- Resistance to deformation
A softer material generally compresses more easily.
However, simply selecting softer rubber isn’t always the best solution.
A properly designed hollow profile can provide significant compression while using a material selected for other important performance characteristics.
Material, hardness, and geometry should be considered together.
Compression Set and Long-Term Performance
Automotive seals can remain compressed for extended periods.
A vehicle door seal, for example, remains compressed whenever the door is closed.
Over time, rubber can experience permanent deformation known as compression set.
If the profile doesn’t recover adequately, sealing performance may decline.
Compression-set behavior can be influenced by:
- Material
- Compound formulation
- Temperature
- Compression percentage
- Profile geometry
- Length of time under compression
Long-term sealing requirements should therefore be considered during the design process.
Temperature Changes in Transportation Applications
Vehicle components can experience substantial temperature fluctuations.
A vehicle parked outside may encounter freezing winter temperatures followed by significant heat during summer.
Components near engines or mechanical systems may experience even more demanding conditions.
Engineers should consider:
- Minimum operating temperature
- Maximum operating temperature
- Continuous temperature
- Intermittent temperature
- Temperature cycling
The material needs to maintain the required physical properties across the expected environment.
UV and Ozone Exposure
Exterior vehicle seals are continuously exposed to environmental conditions.
UV radiation and ozone can cause certain rubber compounds to crack or deteriorate over time.
EPDM provides excellent resistance to both UV and ozone, making it particularly valuable for exterior automotive seals.
Silicone also provides excellent resistance to environmental aging and may be appropriate where additional temperature performance is required.
Vibration in Automotive and Transportation Equipment
Transportation equipment is constantly subjected to vibration.
Engines, road surfaces, tracks, mechanical equipment, and normal vehicle movement can all produce vibration.
Rubber components can help:
- Cushion contact points
- Reduce movement between components
- Protect adjacent surfaces
- Reduce vibration transfer
- Maintain flexible seals
The appropriate profile depends on the magnitude and type of movement involved.
Designing Custom Automotive Rubber Profiles
Standard rubber profiles may work for some applications, but OEM designs often require custom geometry.
A custom extrusion can incorporate features such as:
- Compression bulbs
- Mounting legs
- Channels
- Sealing lips
- Hollow cavities
- Flexible sections
- Multiple sealing surfaces
Combining several features into one extrusion may help simplify the assembly.
Instead of installing multiple separate rubber components, a custom profile may perform several functions simultaneously.
Rubber Extrusion Tolerances
Rubber is flexible and behaves differently from machined metal or rigid plastic.
Dimensions can be affected by:
- Extrusion
- Curing
- Cooling
- Cutting
- Material characteristics
- Profile geometry
Engineers should identify dimensions that are critical to:
- Fit
- Compression
- Installation
- Sealing
- Alignment
Not every dimension necessarily needs the same tolerance.
Applying extremely tight tolerances to non-critical dimensions can increase manufacturing difficulty without improving the performance of the component.
Secondary Operations
Extruded profiles can sometimes require additional processing before installation.
Depending on the project, secondary operations may include:
- Cutting to length
- Joining
- Splicing
- Adhesive application
- Fabrication
- Packaging
These requirements should be considered early in the project.
For example, if an extrusion ultimately needs to be supplied as individual seals rather than continuous lengths, that requirement should be communicated during quoting.
Extrusion vs. Molding for Automotive Rubber Components
Not every vehicle component is best manufactured through extrusion.
Extrusion is ideal for products that maintain a consistent cross section.
Examples include:
- Weatherstripping
- Tubing
- Channels
- Continuous seals
- Protective strips
More complex three-dimensional components may require custom rubber molding.
Molded components can incorporate:
- Variable thickness
- Mounting holes
- Complex surfaces
- Inserts
- Rubber-to-metal bonding
Many transportation assemblies use both molded and extruded rubber components.
Quality Considerations for Transportation Components
Automotive and transportation customers can have demanding quality requirements.
Depending on the project, these may involve:
- Material documentation
- Dimensional inspection
- Traceability
- Production records
- Customer specifications
- Quality documentation
NWRE provides information about its manufacturing quality systems through its Quality Control resources.
Any project-specific documentation or inspection requirements should be identified during the quoting process.
Information to Provide When Requesting a Quote
When requesting a quote for an automotive or transportation extrusion, provide as much information as possible.
Useful information includes:
Drawing: Cross-sectional dimensions and critical tolerances.
Material: Required elastomer or performance requirements.
Durometer: Required hardness if known.
Quantity: Order quantity and estimated annual usage.
Length: Continuous, coiled, or cut lengths.
Temperature: Minimum and maximum operating temperatures.
Environmental exposure: Weather, UV, ozone, water, oil, fuel, or chemicals.
Compression: Available gap and required sealing characteristics.
Application: Explain what the component needs to do.
Secondary operations: Cutting, adhesive, joining, or other fabrication requirements.
This information helps establish the requirements before production begins.
Custom Rubber Extrusions for Transportation Applications
Transportation equipment requires rubber components that can withstand movement, weather, temperature changes, vibration, and long-term use.
The right extrusion depends on more than simply selecting a rubber material.
Successful designs consider:
- Material compatibility
- Profile geometry
- Durometer
- Compression
- Temperature
- Installation
- Tolerances
- Environmental exposure
Evaluating these factors together can help create a profile designed around the actual operating conditions.
Custom Automotive and Transportation Extrusions from NWRE
Northwest Rubber Extruders manufactures custom rubber and silicone profiles for OEM and industrial customers across a variety of industries.
Custom profiles can be manufactured according to customer drawings, material requirements, dimensions, and application specifications.
Explore our Rubber Extrusions, Silicone Extrusions, Material & Engineering, Quality Control, and Industries Served capabilities.
Have a drawing or specification for an automotive or transportation rubber component? Request a Quote from Northwest Rubber Extruders.