Custom rubber extrusions are used in thousands of products across industries ranging from transportation and construction to aerospace, manufacturing, marine, and industrial equipment.
While many rubber extrusions may appear relatively simple, selecting the correct profile, material, hardness, and manufacturing specifications can significantly affect how the finished component performs.
A weather seal installed on an exterior structure, for example, has very different requirements from an industrial gasket exposed to petroleum-based oils. Similarly, a custom extrusion designed to absorb vibration may require different material properties and geometry than one designed to create a watertight seal.
Understanding the fundamentals of custom rubber extrusion can help engineers, designers, purchasing teams, and manufacturers make better decisions when developing new components.
Northwest Rubber Extruders (NWRE) manufactures custom rubber extrusions in a variety of profiles and elastomer materials. This guide explains how rubber extrusion works, common profile designs, material options, applications, and some of the key considerations when designing a custom extruded rubber component.
What Is a Custom Rubber Extrusion?
Rubber extrusion is a manufacturing process used to create continuous lengths of rubber with a specific cross-sectional shape or profile.
During the extrusion process, an uncured rubber compound is forced through a specially designed die. The opening in the die helps form the rubber into the desired profile.
The extruded material then goes through additional processing and curing to establish its final physical properties.
Because the die can be designed around a specific cross-sectional shape, extrusion makes it possible to manufacture a wide variety of custom profiles.
These can range from relatively simple strips and tubing to complex seals with multiple walls, channels, or other design features.
Why Use Custom Rubber Extrusions?
Standard rubber profiles work well for some applications, but many products require a component designed specifically around the finished assembly.
A custom extrusion allows engineers to specify characteristics such as:
- Profile shape
- Dimensions
- Wall thickness
- Material
- Durometer
- Color
- Length
- Tolerances
- Surface characteristics
- Secondary operations
This allows the rubber component to be designed around the application rather than requiring the application to accommodate an existing standard profile.
Custom extrusion can be especially useful when a seal or gasket needs to fit a unique channel, enclosure, frame, piece of equipment, or assembly.
Common Custom Rubber Extrusion Profiles
One of the major advantages of extrusion is the variety of profiles that can be manufactured.
Some common configurations include:
Rubber Tubing
Extruded rubber tubing is used in numerous industrial applications where a hollow, flexible profile is required.
Diameter, wall thickness, material, and hardness can be adjusted depending on the application.
D-Shaped Rubber Profiles
D-shaped extrusions feature a rounded exterior surface and a flatter mounting surface.
These profiles are frequently used as seals, bumpers, cushions, and protective components.
P-Shaped Rubber Profiles
P-shaped profiles typically combine a rounded sealing section with an extended mounting leg.
They may be used around doors, enclosures, machinery, transportation equipment, and other applications requiring compression sealing.
U-Channels
U-shaped rubber channels can fit over an edge or surface to provide protection, cushioning, sealing, or insulation.
Rubber Strips
Solid rectangular or square extrusions can be used for gasketing, spacers, bumpers, vibration isolation, and other industrial purposes.
Hollow Rubber Profiles
Hollow profiles can provide greater compressibility than solid rubber.
When compressed between two surfaces, the hollow section can deform to create a seal while requiring less compression force.
Custom Geometric Profiles
Some applications require unique cross sections that don’t fit into a standard profile category.
Custom tooling allows these shapes to be manufactured around specific dimensional and performance requirements.
What Materials Are Used for Rubber Extrusions?
Selecting the appropriate elastomer is one of the most important steps in designing a custom extrusion.
Different rubber materials provide different levels of resistance to weather, oils, chemicals, temperature, abrasion, and environmental exposure.
Common options include:
EPDM
EPDM is widely used for outdoor and environmental sealing applications.
It offers excellent resistance to:
- Ozone
- Weather
- Water
- UV exposure
- Environmental aging
These characteristics make EPDM popular for construction, automotive, HVAC, transportation, and other outdoor applications.
EPDM generally isn’t recommended when continuous exposure to petroleum-based oils or fuels is expected.
Neoprene
Neoprene provides balanced performance across several categories.
It offers good weather resistance along with moderate resistance to oils, abrasion, and environmental exposure.
This versatility makes Neoprene useful for many general industrial applications.
Nitrile
Nitrile, also known as NBR or Buna-N, is particularly well known for its resistance to petroleum-based oils and fuels.
It is commonly considered for:
- Machinery
- Automotive components
- Industrial equipment
- Oil-resistant seals
- Hydraulic applications
Nitrile generally doesn’t provide the same outdoor weather and ozone resistance as EPDM.
SBR
SBR is a general-purpose synthetic rubber offering useful mechanical and abrasion-resistant properties.
It can provide a cost-effective solution for applications that don’t require specialized resistance to oil, extreme temperatures, or prolonged outdoor exposure.
Silicone
Silicone is commonly considered for demanding temperature environments and applications requiring excellent environmental stability.
It can be manufactured into a wide variety of custom profiles.
NWRE also manufactures custom silicone extrusions for specialized industrial applications.
Additional information about elastomers and material selection is available through NWRE’s Material & Engineering resources.
What Is Rubber Durometer?
Durometer measures the hardness of a rubber material.
This characteristic can significantly affect how a rubber extrusion performs.
A softer rubber compound generally compresses more easily, while a harder compound provides greater resistance to deformation.
Selecting the appropriate durometer depends on the application.
For example, a compression seal may need enough flexibility to conform to irregular surfaces while maintaining sufficient resistance to create an effective seal.
Other applications may require a harder profile that maintains its shape under mechanical stress.
Material type and durometer should therefore be evaluated together.
Solid vs. Hollow Rubber Extrusions
One important design decision is whether to use a solid or hollow profile.
Solid Extrusions
Solid profiles generally provide greater structural resistance and may be appropriate for:
- Bumpers
- Spacers
- Protective strips
- Wear components
- Applications requiring limited compression
Hollow Extrusions
Hollow profiles can compress more easily and are frequently used for sealing.
The hollow cavity allows the profile to deform when pressure is applied.
This can make hollow extrusions useful around:
- Doors
- Hatches
- Equipment enclosures
- Access panels
- Windows
- Transportation equipment
The appropriate design depends on the amount of compression available and the sealing force required.
What Industries Use Custom Rubber Extrusions?
Custom extruded rubber components are used throughout modern manufacturing.
NWRE supplies products for a variety of industries and applications.
Common markets include:
Automotive and Transportation
Rubber extrusions may be used for weather seals, protective profiles, vibration control, equipment seals, and other transportation components.
Aerospace
Aerospace applications can require carefully controlled materials, dimensions, and manufacturing processes.
Rubber and silicone profiles may be used for sealing, protection, vibration control, and environmental isolation.
Construction
Construction products frequently require materials capable of handling prolonged exposure to weather, water, sunlight, and temperature changes.
EPDM and other weather-resistant elastomers are commonly considered for these environments.
Industrial Manufacturing
Industrial machinery and equipment can require rubber profiles for sealing, cushioning, protection, isolation, and vibration control.
Material selection may depend heavily on exposure to oils, chemicals, heat, and mechanical wear.
Marine Applications
Marine environments introduce moisture, weather, UV exposure, and potentially demanding temperature conditions.
The correct elastomer and profile design can help maintain long-term sealing performance.
Railroad and Transit
Rubber products are used in railroad and transit infrastructure for applications involving vibration, isolation, protection, and environmental exposure.
NWRE manufactures specialized products for railroad and transit applications in addition to custom extrusion capabilities.
How Are Custom Rubber Extrusions Designed?
The development process often begins with a drawing, sample, specification, or description of the required application.
Several factors should be considered.
Profile Geometry
The cross-sectional design determines how the extrusion fits into the finished assembly.
Engineers should consider:
- Installation space
- Compression
- Mounting method
- Sealing surfaces
- Wall thickness
- Potential movement
Operating Environment
The environment helps determine which material should be used.
Important questions include:
- Will the component be outdoors?
- Will it encounter sunlight?
- Will it be exposed to oil?
- What temperatures will it experience?
- Will it encounter water?
- Are chemicals present?
- Will it experience abrasion?
Compression Requirements
For sealing applications, the extrusion needs to compress enough to create the desired seal without requiring excessive force.
Profile geometry and durometer both affect compression.
Tolerances
Rubber behaves differently from rigid materials such as metal and plastic.
Realistic dimensional tolerances should be established based on the material, profile geometry, manufacturing process, and application requirements.
Secondary Operations for Rubber Extrusions
Extrusion doesn’t always end when the continuous rubber profile leaves the production line.
Depending on the finished component, additional operations may be required.
These can include:
- Cutting to specific lengths
- Splicing
- Joining
- Adhesive application
- Fabrication
- Packaging
- Other value-added processes
Using secondary operations can allow an extruded profile to arrive closer to its final installation-ready configuration.
Custom Extrusions vs. Molded Rubber Parts
Not every rubber component should be extruded.
Extrusion is generally best suited for products that maintain the same cross-sectional profile along their length.
Molding may be more appropriate when a component requires a complex three-dimensional geometry.
Examples might include specialized gaskets, boots, bumpers, diaphragms, or components with shapes that change substantially across multiple dimensions.
NWRE provides both custom extrusion and rubber molding capabilities, allowing different manufacturing processes to be considered based on the requirements of the component.
How to Choose a Custom Rubber Extrusion Manufacturer
Choosing a manufacturing partner involves more than finding a company capable of pushing rubber through a die.
Important considerations can include:
- Experience with different elastomers
- Custom tooling capabilities
- Quality-control procedures
- Ability to work from customer drawings
- Material knowledge
- Secondary operations
- Industry experience
- Production capabilities
- Quality certifications
For demanding applications, quality systems can be especially important.
NWRE maintains quality-control processes and certifications supporting manufacturing for a variety of industries and applications.
Questions to Answer Before Requesting a Quote
Providing complete information can help make the quoting and manufacturing process more efficient.
Before requesting pricing for a custom extrusion, try to identify:
What is the profile shape?
Provide a drawing whenever possible.
What material is required?
If you’re unsure, provide information about the operating environment.
What durometer is needed?
This may already be specified on an engineering drawing.
What are the dimensions and tolerances?
Identify dimensions that are particularly important to the application.
What quantity is required?
Expected production volumes can affect manufacturing and tooling decisions.
What lengths are needed?
Specify continuous lengths or cut lengths.
Are secondary operations required?
Identify cutting, adhesive, joining, or other finishing requirements.
What is the operating environment?
Include temperature, chemicals, oils, weather, water, and other relevant conditions.
Finding the Right Custom Rubber Extrusion Solution
A successful custom extrusion begins with understanding how the component needs to perform.
Material, profile geometry, durometer, dimensions, tolerances, and environmental exposure all work together to determine whether a finished extrusion will meet the application’s requirements.
EPDM may be appropriate for an outdoor weather seal, while nitrile may be better suited for an oil-resistant industrial component. Silicone may be considered when demanding temperature performance is required.
There is no single material or profile that works for every application.
Working through these requirements early in the design process can help identify potential problems before tooling and production begin.
Talk to Northwest Rubber Extruders About Your Project
Northwest Rubber Extruders manufactures custom rubber, silicone, and flexible plastic extrusions for customers across a wide range of industries.
Whether you’re developing a completely new component or replacing an existing rubber profile, NWRE can manufacture custom extrusions based on customer drawings and specifications.
Learn more about our Rubber Extrusions, Silicone Extrusions, Material & Engineering, and Industries Served capabilities.
Have a drawing or specification ready? Request a Quote to discuss your custom extrusion project with Northwest Rubber Extruders.