Whether it’s an automotive production line, a transit vehicle manufacturer, a commercial building systems supplier, or an industrial equipment OEM, reliable weather sealing is critical to long-term product performance. For manufacturers requiring thousands of feet of custom sealing profiles, thermoplastic elastomer extrusion offers an efficient, scalable solution. Rain, snow, heat, freezing cold, UV rays, wind-driven debris, the elements are relentless, and any product exposed to the outdoors needs protection that can stand the test of time.

This is exactly where thermoplastic weather seals come in. And the manufacturing process that makes these high-performance seals possible is called thermoplastic elastomer extrusion, a precise, controlled process that transforms raw TPE material into long-lasting weatherproofing components.

In this blog, we’ll explore how thermoplastic elastomer extrusion works, why it produces superior thermoplastic weather seals compared to traditional rubber, and what makes this manufacturing process so important across industries that demand reliable, all-weather performance.

What Is a Thermoplastic Weather Seal?

A thermoplastic weather seal is a sealing component designed specifically to protect against environmental elements, water, air, dust, UV radiation, and temperature extremes. These seals are commonly found around:

• Vehicle doors, windows, trunks, and hoods
• Building windows, doors, and curtain walls
• Outdoor electrical and industrial enclosures
• Transit vehicle doors and windows (buses, trains)
• HVAC equipment and ductwork

In commercial and industrial environments, weather seals are often specified in high-volume production programs requiring consistent quality across thousands or even millions of linear feet annually. Unlike standard indoor gaskets, thermoplastic weather seals must endure constant exposure to sunlight, rain, temperature swings, and physical wear over many years, all while maintaining a tight, reliable seal.

The material of choice for high-performance thermoplastic weather seals is Santoprene™ TPV (thermoplastic vulcanizate), prized for its rubber-like flexibility combined with plastic-like processability and outstanding weather resistance.

What Is Thermoplastic Elastomer Extrusion?

Thermoplastic elastomer extrusion is the manufacturing process used to produce continuous-length profiles from TPE or TPV materials. In this process, thermoplastic elastomer pellets are melted and forced through a precision-shaped die, creating a continuous profile that is then cooled, cut, and finished into the final product, such as a thermoplastic weather seal.

This process differs significantly from traditional rubber compression molding or injection molding. Because thermoplastic elastomers can be melted and reshaped repeatedly (unlike vulcanized rubber, which is permanently cross-linked), thermoplastic elastomer extrusion offers faster production speeds, more consistent quality, and greater design flexibility. One of the major advantages of thermoplastic elastomer extrusion is its ability to support high-volume manufacturing programs while maintaining tight dimensional tolerances across long production runs

How Thermoplastic Elastomer Extrusion Works: Step by Step

Understanding the extrusion process helps explain why thermoplastic weather seals made this way perform so much better in real-world conditions.

Step 1: Material Preparation

The process begins with selecting and preparing the right TPE or TPV compound. For weather seal applications, materials are chosen based on:

• UV and ozone resistance
• Operating temperature range
• Flexibility and compression set performance
• Color and surface finish requirements

Santoprene™ TPV is typically supplied in pre-compounded pellet form, ready for extrusion, with consistent hardness (Shore A durometer) and performance characteristics from batch to batch.

Step 2: Die Design and Fabrication

A custom extrusion die is precision-machined to create the specific cross-sectional shape required for the weather seal application, whether it’s a simple flat strip, a hollow bulb seal, a U-channel, or a complex multi-cavity profile with integrated mounting flanges.

Die design must account for material shrinkage, die swell, and the draw-down ratio to ensure the final extruded profile matches the exact dimensions required.

Step 3: Extrusion

The TPE pellets are fed into a heated extruder barrel, where a rotating screw melts and conveys the material forward. The molten material is then forced through the die under controlled pressure, emerging as a continuous profile in the exact shape needed.

Extrusion temperatures for Santoprene™ TPV typically range from 160°C to 220°C, depending on the specific grade and profile complexity.

Youtube video link – https://youtu.be/n0Kbra6mIIc?si=o4TPM1T3lEbfn7HK

Step 4: Cooling and Sizing

As the profile exits the die, it passes through a cooling system, either a water trough or air cooling, to solidify the shape while it is still hot and malleable. Proper cooling is essential to lock in accurate dimensions and prevent warping or distortion.

Step 5: Haul-Off and Cutting

A haul-off unit pulls the cooled profile at a precisely controlled speed matched to the extrusion rate. The continuous profile is then cut to length using precision cutting equipment, such as digital oscillating knife systems, which deliver clean, accurate cuts with minimal waste.

Step 6: Finishing and Assembly

Depending on the application, additional finishing steps may be performed, including:

• Corner welding or splicing to create closed-loop seals for window and door frames
• Adhesive tape application for easy peel-and-stick installation
• Co-extrusion of multiple materials or colors in a single profile (e.g., a rigid base with a soft sealing lip)
• Custom packaging such as coiling or straight-length boxing

Why Thermoplastic Elastomer Extrusion Produces Superior Weather Seals

Compared to traditional rubber weatherstripping, thermoplastic weather seals made through thermoplastic elastomer extrusion offer several key advantages:

1. Exceptional Weather Resistance

Santoprene™ TPV and similar materials offer outstanding resistance to UV radiation and ozone exposure, two of the biggest causes of premature failure in outdoor rubber seals. While standard EPDM rubber can crack and degrade after prolonged sun exposure, thermoplastic weather seals maintain their flexibility and sealing performance for many years longer.

2. Wide Temperature Performance

Thermoplastic weather seals manufactured through proper thermoplastic elastomer extrusion processes maintain flexibility and sealing force across an extremely wide temperature range, typically from -40°C to +135°C. This makes them ideal for applications that experience extreme seasonal temperature swings.

3. Consistent Quality and Dimensional Accuracy

Because thermoplastic elastomer extrusion is a continuous, closely monitored process, dimensional consistency is significantly better than batch-cured rubber. This results in weather seals that fit precisely and perform consistently across the entire production run.

4. Low Compression Set

A good weather seal needs to maintain its sealing force over time, even after years of being compressed in a closed position (such as a door or window seal). Thermoplastic elastomers exhibit excellent compression set resistance, meaning they “spring back” and maintain sealing pressure far better than standard rubber compounds over the long term.

5. Design Flexibility for Complex Profiles

Thermoplastic elastomer extrusion allows for the creation of highly complex profile geometries, including hollow bulb seals, multi-durometer co-extrusions, and integrated mounting features, that would be difficult or expensive to achieve with traditional rubber extrusion or molding.

6. Recyclability and Sustainability

Unlike vulcanized rubber, thermoplastic elastomers can be reprocessed and recycled. This makes thermoplastic weather seals a more environmentally responsible choice for manufacturers aiming to reduce waste and improve sustainability credentials.

7. Faster Lead Times and Lower Tooling Costs

Extrusion tooling (dies) is significantly less expensive and faster to produce than injection or compression molds. This means thermoplastic weather seals can go from design to production faster, with lower upfront investment, a major advantage for new product development.

High-Volume Applications for Thermoplastic Weather Seals

The combination of superior material properties and the flexibility of thermoplastic elastomer extrusion makes thermoplastic weather seals the preferred choice across many industries. These applications typically require ongoing production volumes ranging from several thousand feet to hundreds of thousands of feet annually.

Automotive

Door seals, trunk seals, hood seals, and window run channels all rely on thermoplastic weather seals to keep water and noise out while withstanding years of sun exposure and temperature cycling.

Building & Construction

Window perimeter seals, door weatherstripping, and curtain wall gaskets depend on thermoplastic weather seals to maintain energy efficiency and prevent water infiltration in all climate conditions.

Mass Transit

Bus and train doors and windows require robust weather seals that can withstand constant opening and closing cycles, vibration, and outdoor exposure over the vehicle’s operational lifespan.

Industrial Enclosures

Outdoor electrical cabinets, control panels, and equipment housings use thermoplastic weather seals to maintain IP-rated environmental protection against dust and moisture ingress.

HVAC Systems

Ductwork and equipment access panels use weather seals to maintain airtight performance and prevent energy loss, even when exposed to temperature extremes.

Choosing the Right Thermoplastic Weather Seal Manufacturer

When selecting a manufacturing partner for thermoplastic elastomer extrusion and thermoplastic weather seals, manufacturers should consider:

• Material expertise – deep knowledge of TPE/TPV formulations and their performance characteristics
• In-house tooling capability – faster turnaround and better design collaboration
• Quality certifications – ISO 9001 at minimum, with additional certifications relevant to your industry
• Testing capabilities – ability to verify compression set, tensile strength, hardness, and weathering performance
• Production flexibility – capacity to handle both prototype runs and high-volume production
• Value-added services – cutting, splicing, corner joining, and adhesive backing options

Conclusion

When it comes to protecting products from the elements, not all seals are created equal. Thermoplastic elastomer extrusion has become the manufacturing process of choice for producing high-performance thermoplastic weather seals that outlast and outperform traditional rubber weatherstripping in nearly every measurable way, from UV resistance to compression set to long-term durability.

For manufacturers across automotive, construction, transit, and industrial sectors, investing in quality thermoplastic weather seals isn’t just about sealing out water and air it’s about protecting product performance, reducing warranty claims, and building a reputation for quality that lasts for years.

About Santop Seal Corporation

Santop Seal Corporation is a leading USA-based manufacturer specializing in thermoplastic elastomer extrusion and high-performance thermoplastic weather seals. Based in Pittsburgh, Pennsylvania, SantopSeal serves customers across automotive, construction, medical, food and beverage, industrial, and mass transit industries with precision-engineered sealing solutions.

SantopSeal manufactures all thermoplastic weather seals using premium Santoprene™ TPV material from Celanese, delivering consistent quality and outstanding weather resistance for the most demanding outdoor applications. All products are proudly Made in the USA.

Products Offered:

• Custom Extruded Seals & Gaskets (U, P, D, E, H, T Channel Profiles)
• Thermoplastic Weather Seals & Weatherstripping
• Santoprene™ TPE/TPV Tubing (General, Food Grade, Medical Grade)
• Custom & Standard O-Rings
• EPDM Sponge Rubber Seals
• Santoprene Rubber Sheets
• Custom Molded Rubber Products
• Custom Refrigeration Gaskets
• Viton™ Tubing, Cord, Strip & Square
• Flash Knife Cutting Services
• 3D Printing Services

Certifications & Compliance:

ISO 9001 | NSF 51 & NSF 61 | USP Class VI | RoHS Compliant | UL 94 V-0

Contact SantopSeal Corporation:

• Phone: +1 (412) 444-1888
• Email: info@santopseal.com
• Website: https://www.santopseal.com/
• USA Address: 3 Nicholson Dr, Cuddy (Pittsburgh), PA 15031