Overmolding: When to use Adhesive Coating

An operator applies adhesive coating to a metal carrier at our manufacturing plant in Mexico

Overmolding is a specialized manufacturing process that results in a seamless combination of multiple materials into a single part. Some overmolded seals use a physical bond, while others require a chemical bond. For overmolded seals that require a chemical bond, specialized adhesive coatings are often used due to several key reasons:

1. Enhanced Bonding: Adhesive coatings improve the bonding between the rubber material and the carrier, which is typically made of metal or plastic. A chemically enhanced bond helps to ensure a tight seal for the overmolded gasket, crucial for preventing leaks of fluids, gases, and contaminants within automotive systems.

An operator inspects a Thermostat Housing Gasket made from HNBR overmolded onto an aluminized steel carrier

2. Temperature and Chemical Resistance: Automotive gaskets and seals are exposed to a wide range of temperatures and chemicals, such as engine heat, oil, fuel, and coolant. Specialized adhesive coatings are formulated to withstand these harsh conditions, maintaining bond integrity and seal performance over the lifespan of the vehicle.

3. Vibration and Mechanical Stress Mitigation: Vehicles experience constant vibrations and mechanical stresses during operation, which can weaken gasket seals over time. Adhesive coatings help to strengthen the bond between the rubber and carrier, reducing the risk of seal failure due to vibration-induced fatigue.

4. Compatibility with Diverse Materials: Automotive gaskets often involve joining rubber with various substrate materials, each with its own properties and challenges. Specialized adhesive coatings are tailored to promote adhesion and compatibility across different materials, minimizing the risk of delamination and ensuring a durable bond.

A specialized coating is applied to a metal carrier for a Flywheel Housing Gasket

5. Durability and Longevity: The demanding operational conditions of automotive systems require gaskets and seals to maintain their integrity over extended periods. Adhesive coatings enhance the durability and longevity of overmolded gaskets by providing superior bonding strength and resistance to environmental factors, contributing to the reliability of automotive components.

Here’s a quick video that demonstrates our use of a specialized adhesive coating to prep a metal carrier during the manufacturing of overmolded gaskets in Mexico.

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To learn more about rubber and plastic overmolding, here’s a 3-minute video that shows how we manufacture gaskets for automotive OEMs from our plant in Mexico:

Manufacturing overmolded gaskets and seals for automotive applications in Mexico