Extruded Automotive Seals

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Extruded Seal Types & Applications


We manufacture a variety of dual- and tri- durometer extruded seals such as trim seals, edge seals, bulb seals, bubble seals, hatch seals, flap seals, and others, with a focus in automotive seals.

A wireframe of a vehicle with blue lines indicating the locations of extruded seals.

  • Sunroof seals
  • Radiator seals
  • Hood seals
  • Cowl seals

  • Instrument panel seals
  • Pillar seals
  • HVAC seals
  • Closeout seals

  • Windshield laces
  • Condenser seals

Our FEA Engineers can recommend the best design and material for your application.

Why Choose Gemini?


We’ve been solving our customers’ sealing challenges for decades. We have the experience and technology to solve yours, too. Our team has engineered and built over 5,000 custom plastic extrusion and co-extrusion profiles with 99.99% accuracy and 99.72% on-time delivery. Here’s how:

DFM & DFA Engineering

We’re not just a manufacturer, we’re a partner in engineering. We take a DFMA approach to everything we do. This allows us to simplify, re-engineer, and drive cost out of your extruded seal, all while maintaining or improving its form, fit, and function. The result? Elegant, multi-function, reliable seals designed for lean assembly.

Automotive Expertise

We know the industry. With dozens of OEM and Tier 1 customers across the globe, we’re more than capable of meeting and surpassing tough quality standards, delivery demands, and budget constraints for high-volume orders. Our automotive seal customers are well-served by our strategically-located manufacturing and logistics facilities across North America.

In-House Tooling

From the ground up, we get it right for our customers. If your seal design can’t be matched to an existing extrusion profile, we’ll design and build the right tooling, in house. This includes prototype and production extrusion dies, trim and fabrication tools, fixtures and gauges, and anything else to assist in optimal design, manufacturing, and performance of your custom extruded plastic seal.


Complex sealing challenges don’t require complex solutions. In fact, we can achieve multiple characteristic properties by combining two or more materials in one step using co-extrusion.

In-Line Processing

We can apply tape, flock, and slip coat to your seal right on the extrusion line, reducing the need for secondary processes and operations.

Secondary Operations

Welding, insert/over molding, and other secondary operations for your seal are done in-house to reduce lead times and non-value added costs such as shipping to another facility.


As a Women’s Business Enterprise National Council (WBENC) certified minority-owned business, we proudly contribute to our customers’ supplier diversity programs.

Process Simulation Software

Our extrusion simulation software allows us to balance the material flow before any tooling is cut. This reduces the number of tool iterations, allows for a quicker completion of production tooling, shortens your time-to-market, and ultimately saves on manufacturing costs.

Testing Laboratory

We’re armed with an array of testing equipment to ensure that you receive consistent, reliable, high-quality products that meet your specifications and regulations.



Cost creep can kill your plastic seal program. While it’s impossible to predict every single cost an extruded plastic seal program will incur, you can minimize unpredictability and cost-creep by simplifying your design. The following list is by no means exhaustive, but it does cover the major cost-drivers that you should consider:


Typically, the more complex the seal, the more expensive it will be to engineer and manufacture. Features such as hollows, semi-hollows, narrow die sections, non-identical thickness, tight tolerances, and living hinges should be avoided whenever possible.

Design Changes

Any change to the quoted seal design can result in increased cost, especially if it happens after the initial tooling has been built. For this reason, we conduct extensive feasibility testing and simulations for our customers before the manufacturing process begins to minimize the risk of expensive design changes.


There is more to tooling than the extrusion die itself. Of course, the more complex the die the more expensive it will be to make, but you should also consider the cost of any trim or fabrication tools you’ll need after the initial seal is extruded, as well as fixtures and gauges to support the seal during secondary operations.

Quality & Accuracy


If you’re like most OEMs, it costs thousands of dollars each minute a production line shuts down due to a faulty seal. That’s why we use the latest in quality control technology before, during, and after the seal extrusion process. But many mistakes happen outside of manufacturing that can negatively impact your seal, too:

Failure to consider all failure modes:

  • Exposure to chemical, heat, fatigue, abrasion, tear, set, ozone
  • Stresses and strains from the surrounding systems
  • Effect of surrounding water management systems
  • Packaging and shipping requirements
  • Assembly, installation, and service constraints

Supplier Inexperience:

  • Inadequate material options and recommendations
  • Inattention to detail or a “shoot-and-ship” culture
  • Overestimation of seal tolerances and capabilities
  • Lack of experience in packaging and shipping seals
  • Underestimating high-volume logistical needs
  • Lack of certifications and processes for quality control


  • Changes with interfacing components and surfaces
  • Mismanaged timing, specification, tolerance, and cost expectations

Gemini Group lives in the automotive world; it’s woven into our culture. We have all the certifications, we build value into every product we produce, we have experience shipping over 600 million parts a year … we have the commitment it takes to engineer and manufacture a successful automotive seal.


  • PP – Polypropylene
  • Glass-filled
  • Talc-filled
  • PVC – rigid & flexible
  • ABS
  • Nylon
  • PS – Polystyrene
  • Polycarbonate
  • Acrylic
  • +50 specialty resins
  • Class A – color-matched
  • Graining
  • Foaming agents

Extruded Seals Terminology

  • Blooming: A phenomenon that occurs when compounding agents in rubber migrate, or bloom, to the surface, causing a dusty or milky looking film. This is due to the agents’ limited compatibility with the rubber elastomer and affects the tensile strength, adhesion properties, and appearance of your part.
  • Slipcoat: A non-drip lubricant applied to the surface of seals to reduce friction and increase surface smoothness and abrasion resistance.
  • Flock tape/spray: An adhesive tape or with a non-woven coating on one side or an adhesive non-woven spray that is used to reduce friction between two surfaces or reduce reflection.
  • Hollow: A hollow area, usually ¼” to 5” in diameter, in a profile design made by placing a pin or mandrel inside the die.
  • Durometer: A measurement usedto indicate the hardness of a material, defined as a material’s resistance to permanent indentation.
  • Compression set: The permanent indentation remaining when a force that was applied to a material is removed. There are two ways to measure compression set: Compression set A measures the materials thickness before and after pressure is applied. Compression set B measures the material thickness after the material is compressed to 25% of its original height.
  • Insertion/extraction forces: The forces applied to the seal during assembly and disassembly in its final application.
  • Insert molding: Molding one material (plastic) around another (metal) such that the final component is single unit with reduced assembly and labor costs, reduced the size and weight of the part, improved component reliability, and improved part strength and structure with enhanced design flexibility.

Resources for Engineers


We’re here to help you optimize your plastic seal design. So,


As you’re considering your next conversation with Gemini, enjoy these free resources: