Custom rubber extrusions are used throughout industrial equipment, transportation, construction, aerospace, manufacturing, and many other industries. While the material used to manufacture an extrusion is important, the shape of the rubber profile is equally critical to how the finished component performs.
Rubber extrusion makes it possible to manufacture continuous profiles in a wide variety of shapes, from simple strips and tubing to hollow bulb seals and completely custom geometries.
Each profile serves a different purpose.
Some are designed to compress and create a seal. Others protect edges, fill gaps, absorb impact, reduce vibration, or provide a flexible channel between components.
Northwest Rubber Extruders (NWRE) manufactures custom rubber extrusions for industrial and OEM applications.
Below are some of the most common types of rubber extrusion profiles and factors to consider when designing a custom profile for your application.
What Is a Rubber Extrusion Profile?
A rubber extrusion profile is a continuous length of rubber manufactured with a consistent cross-sectional shape.
During the extrusion process, uncured rubber is forced through a die containing an opening designed to create the desired profile.
The extrusion is then processed and cured to establish its final physical properties.
Because the profile is produced continuously, extrusion is ideal for components that maintain essentially the same cross-sectional geometry throughout their length.
Examples include:
- Seals
- Gaskets
- Tubing
- Channels
- Strips
- Weatherstripping
- Bumpers
- Edge protection
- Hollow profiles
Custom tooling can also be developed when an existing standard profile doesn’t meet the application’s requirements.
1. D-Shaped Rubber Profiles
D-shaped rubber extrusions are commonly used as compression seals.
When viewed from the end, the profile resembles the letter “D,” typically with a flat mounting surface and rounded sealing surface.
The rounded portion compresses when two surfaces come together.
Common D-Profile Applications
D-shaped rubber seals may be used for:
- Equipment doors
- Enclosures
- Hatches
- Cabinets
- Automotive applications
- Transportation equipment
- Industrial machinery
- Weather sealing
D-shaped profiles may be solid or hollow depending on the required compression characteristics.
A hollow D-profile generally compresses more easily than a comparable solid profile.
2. P-Shaped Rubber Profiles
P-shaped profiles typically combine a rounded or hollow sealing section with an extended mounting leg.
Viewed from the end, the shape resembles the letter “P.”
The extended portion can provide a surface for mounting or positioning the extrusion, while the bulb section creates the seal.
Common P-Profile Applications
P-shaped seals may be used around:
- Doors
- Hatches
- Access panels
- Machinery
- Vehicles
- Industrial equipment
- Enclosures
The profile geometry can be customized based on the required mounting method and compression.
3. Bulb Seals
Bulb seals use a hollow rounded section designed to compress under pressure.
The hollow cavity allows the profile to deform relatively easily.
This makes bulb seals useful when a significant amount of compression is required without excessive closing force.
Common Bulb Seal Applications
Bulb seals may be used for:
- Equipment doors
- Vehicle compartments
- Enclosures
- Access panels
- HVAC equipment
- Cabinets
- Construction products
Bulb geometry can vary considerably.
The bulb may be circular, oval, rectangular, or incorporated into a more complex custom profile.
4. U-Channel Rubber Profiles
U-channel extrusions are designed to fit over an edge or into a specific mounting configuration.
Viewed from the end, they generally resemble the letter “U.”
The channel can help protect an edge, provide cushioning, isolate components, or create a finished surface.
Common U-Channel Applications
U-channel rubber profiles may be used for:
- Edge protection
- Metal panels
- Glass protection
- Machinery
- Automotive components
- Industrial equipment
- Construction products
The dimensions of the channel should be designed around the thickness of the material it needs to fit.
5. Rubber Tubing
Rubber tubing is another common extruded profile.
Tubing typically consists of a round outer diameter with a hollow center, although custom tubing configurations may also be manufactured.
Important tubing dimensions include:
- Outside diameter
- Inside diameter
- Wall thickness
Common Rubber Tubing Applications
Depending on the material and design, extruded rubber tubing may be used for:
- Protective sleeves
- Industrial equipment
- Cushioning
- Sealing
- Insulation
- Fluid-related applications
- Mechanical protection
Material selection becomes especially important if tubing will encounter chemicals, oils, temperature extremes, or environmental exposure.
6. Solid Rubber Strips
Not every custom extrusion requires complex geometry.
A simple solid rubber strip can be useful for many industrial applications.
Solid strips can be manufactured in different:
- Widths
- Thicknesses
- Materials
- Durometers
Common Rubber Strip Applications
Rubber strips may be used for:
- Spacers
- Gaskets
- Protective surfaces
- Bumpers
- Cushioning
- Isolation
- Wear protection
- Gap filling
The simplicity of the profile can make rubber strips a versatile option when complex sealing geometry isn’t required.
7. Rectangular Rubber Profiles
Rectangular profiles are similar to rubber strips but may be designed with dimensions appropriate for more specialized applications.
They can be manufactured as solid or hollow profiles.
Solid Rectangular Profiles
These may be used when greater resistance to compression or deformation is needed.
Hollow Rectangular Profiles
An internal cavity can increase compressibility.
Hollow rectangular seals may be useful around:
- Doors
- Equipment
- Industrial enclosures
- Access panels
The cavity shape and wall thickness can be adjusted to influence compression characteristics.
8. Hollow Rubber Profiles
Hollow rubber extrusions are particularly valuable for sealing applications.
Instead of relying entirely on a soft rubber compound, the profile’s internal cavity allows the rubber to deform when compressed.
This can create an effective seal using less force than might be required with a solid profile.
Hollow profiles can take many shapes, including:
- Round
- Oval
- Rectangular
- D-shaped
- Bulb-shaped
- Custom geometries
Profile design can have a major effect on how the seal responds to pressure.
9. Rubber Edge Trim
Rubber edge profiles can help cover or protect exposed edges.
Depending on the application, they may provide:
- Impact protection
- Abrasion protection
- Cushioning
- Noise reduction
- A finished appearance
Edge trim profiles may be designed around the thickness and geometry of the surface they need to cover.
10. Custom Weatherstripping Profiles
Weatherstripping is used to help reduce the movement of water, air, dust, and other environmental elements through gaps.
Weather seals may incorporate several profile styles, including:
- D-shaped seals
- P-shaped seals
- Bulb seals
- Hollow profiles
- Channels
- Custom geometries
Material selection is especially important for exterior weatherstripping.
EPDM is commonly considered for outdoor weather seals because of its resistance to ozone, UV exposure, water, and environmental aging.
Silicone extrusions may also be considered when demanding temperature conditions or other specialized requirements are involved.
11. Custom Rubber Gasket Profiles
Not every gasket needs to be molded.
A continuous rubber extrusion can sometimes be cut and fabricated into a finished gasket.
For example, a custom profile may be:
- Extruded continuously
- Cut to the required dimensions
- Joined or spliced
- Fabricated into a finished gasket
This approach may be appropriate when the gasket maintains the same cross-sectional profile around its perimeter.
More complex three-dimensional components may instead require custom rubber molding.
12. Completely Custom Rubber Profiles
Standard profile shapes don’t work for every application.
A custom rubber extrusion can be designed around the specific geometry of a customer’s assembly.
Custom profiles may combine multiple features into one extrusion.
For example, a single profile might incorporate:
- A mounting channel
- A flexible hinge
- A compression bulb
- A sealing lip
- A protective edge
This can potentially reduce the number of separate components required within an assembly.
Custom profiles can be manufactured from customer drawings and specifications.
Solid vs. Hollow Rubber Profiles
One of the biggest decisions in profile design is whether the extrusion should be solid or hollow.
Solid Profiles
Solid rubber generally provides greater resistance to compression and deformation.
It may be appropriate for:
- Bumpers
- Protective strips
- Spacers
- Wear surfaces
- Certain gaskets
- Edge protection
Hollow Profiles
Hollow profiles are generally easier to compress.
They are commonly considered for:
- Door seals
- Weather seals
- Enclosures
- Hatches
- Equipment seals
Neither design is automatically better.
The appropriate choice depends on what the extrusion needs to accomplish.
Choosing the Right Rubber Material for the Profile
Profile geometry is only half of the design.
The rubber material needs to withstand the operating environment.
Common elastomers include:
EPDM
EPDM provides excellent resistance to:
- Weather
- Ozone
- UV exposure
- Water
- Environmental aging
It is commonly considered for outdoor seals and weatherstripping.
Neoprene
Neoprene provides balanced physical and environmental properties and may be appropriate for many general industrial applications.
Nitrile
Nitrile is commonly selected when resistance to petroleum-based oils or fuels is important.
SBR
SBR is a general-purpose synthetic rubber that can provide useful mechanical and abrasion-resistant properties.
Silicone
Silicone is particularly valuable when temperature extremes or specialized performance requirements are involved.
NWRE’s Material & Engineering resources provide additional information related to material selection.
How Durometer Affects Rubber Profiles
Durometer measures rubber hardness.
The appropriate durometer depends on the function of the profile.
A softer rubber generally:
- Compresses more easily
- Provides greater flexibility
- Conforms more readily to surfaces
A harder rubber generally:
- Resists deformation
- Requires greater compression force
- May provide increased physical resistance in certain applications
However, profile geometry can dramatically change compression characteristics.
A hollow profile made from a harder compound may still compress more easily than a solid profile made from a softer compound.
Material hardness and geometry should therefore be considered together.
Designing Rubber Profiles for Compression
If a rubber extrusion will function as a seal, engineers should determine how much space is available for compression.
Important considerations include:
- Gap between surfaces
- Expected compression
- Closing force
- Surface variation
- Movement during operation
- Frequency of compression
- Temperature
- Compression set
Too little compression may prevent the profile from creating sufficient contact.
Too much compression may increase closing force or place unnecessary stress on the rubber and surrounding assembly.
The seal should be designed around the actual conditions in which it will operate.
Tolerances for Custom Rubber Profiles
Rubber is a flexible material, so extrusion tolerances should reflect the functional requirements of the part.
Engineers should identify which dimensions are critical to:
- Installation
- Fit
- Compression
- Sealing
- Alignment
Not every dimension necessarily needs the same tolerance.
Applying unnecessarily tight tolerances to non-critical dimensions can create manufacturing challenges without improving the performance of the finished component.
Discussing critical dimensions before tooling can help establish practical manufacturing requirements.
Industries That Use Custom Rubber Extrusion Profiles
Custom rubber profiles are used across a broad range of markets.
Examples include:
Transportation
Weather seals, protective profiles, tubing, vibration isolation, and other components.
Construction
Weatherstripping, building seals, edge protection, and specialty profiles.
Industrial Manufacturing
Machine seals, protective strips, channels, bumpers, and custom components.
Aerospace
Specialized sealing profiles and components requiring specific material properties.
HVAC
Equipment seals, access-panel gaskets, and weather-resistant profiles.
Railroad and Transit
Specialized elastomeric components used in rail and transportation applications.
NWRE serves customers across numerous industries with different material and performance requirements.
What Information Is Needed for a Custom Rubber Profile?
When requesting a quote for a custom extrusion, providing detailed information can make the process more efficient.
Whenever possible, include:
Profile drawing: Provide the cross-sectional dimensions.
Material: Identify the elastomer if it has already been selected.
Durometer: Specify the required hardness.
Tolerances: Identify dimensions critical to performance.
Quantity: Provide anticipated order quantities or annual usage.
Length: Specify continuous, coiled, or cut lengths.
Operating environment: Include temperature, weather, water, oils, chemicals, UV, and other exposure.
Application: Explain what the profile actually needs to accomplish.
Secondary operations: Identify cutting, joining, adhesive, or fabrication requirements.
Providing application information in addition to a drawing can help identify potential design and manufacturing considerations earlier in the process.
Choosing the Right Rubber Extrusion Profile
There isn’t one profile shape that works for every application.
The right design depends on:
- What the component needs to do
- How much it needs to compress
- How it will be installed
- What environment it will encounter
- Required material properties
- Available space
- Mechanical forces
- Dimensional requirements
A simple solid strip may be all that’s required for one application.
Another project may require a custom hollow profile incorporating a mounting channel and compression bulb.
The best solution comes from evaluating material, geometry, installation, and operating conditions together.
Custom Rubber Extrusion Profiles from Northwest Rubber Extruders
Northwest Rubber Extruders manufactures custom extruded rubber profiles for customers across a variety of industrial markets.
From simple strips and tubing to D-shaped seals, channels, hollow profiles, and complex custom geometries, extrusions can be manufactured according to customer drawings and specifications.
Explore NWRE’s Rubber Extrusions, Silicone Extrusions, Material & Engineering, and Industries Served capabilities.
Have a drawing for a custom rubber profile? Request a Quote from Northwest Rubber Extruders.