Rubber to metal bonding is an umbrella term for the processes used to bind an elastomer to a pre-treated metal surface. These processes are suitable for producing parts and products with both the strength characteristic of steel and the flexibility or chemical resistance characteristic of rubber.
The Rubber to Metal Bonding and Molding Process
In general, rubber to metal bonding operations include the following steps:
- Material identification: The materials used in rubber to metal bonding processes are chosen based on the intended application for the end product. If the product will be exposed to extreme temperatures, harsh chemicals, or excessive moisture, the elastomer used must be able to withstand these environmental and operational elements. The appropriate metal should be chosen based on similar characteristics. Standard options for the elastomer include natural rubber and neoprene.
- Surface preparation: Once the material has been selected, the surface needs to be prepared. To ensure full bonding of the rubber, the metal’s surface needs to be free of oil, rust, and other contaminants. Depending on the state of the metal used, surface preparation might require solvent degreasing, alkaline cleaning, mechanical washing treatments, or other processes.
- Primer and adhesive application: To prevent contamination, adhesive application begins immediately after surface preparation. Industry-leading LORD adhesive systems feature two layers—a primer and an adhesive topcoat—that are applied sequentially to the metal surface. The metal can be sprayed, dipped, or rolled in the adhesive so long as an even coat is achieved.
- Molding: The molding process generally involves compression, transfer, or injection molding. The metal is “located” into the mold cavity. While secured in the cavity, the rubber will flow in and around the metal. Under heat and pressure, the rubber and adhesives cure and crosslink. It is important that the metal not sit in the cavity too long before molding as the adhesive can pre-cure and cause failures.
- Testing: Once the adhesive has fully cured, service providers perform quality assurance tests to ensure the parts meet the specified requirements. Typical tests focus on key parameters, such as tensile strength.
Types of Adhesive Systems for Rubber to Metal Bonding Processes
During the molding stage, the adhesive system allows the rubber material to form a durable bond with the metal part. The types of adhesive systems available include:
- One-coat adhesive. In a one-coat system, the adhesive and primer are combined into a single spray that is applied in one step. As the primer step is eliminated, this system can reduce processing time, increase output, and reduce costs. However, it is not as durable or versatile as other adhesive systems.
- Two-coat adhesive. Separating the primer and adhesive application makes it possible to achieve more advanced characteristics compared to a one-coat process. For instance, two-component adhesives—such as the LORD adhesive system—often offer better corrosion resistance and are less susceptible to water damage or chemical exposures. They also tend to perform better overall, including on measures of dynamic and static fatigue.
- Water-based adhesive. These systems are recognized as being safer and more environmentally friendly because they eliminate the use of chemical solvents. This quality also reduces the health risk to employees, lowers the amount of VOCs emitted, and makes them easier to store.
The choice of adhesive system is an important one, and our team at Molded Products can help guide you toward the optimal solution for your application. Our experience working with diverse clients informs our advice, giving us insight into industry-specific requirements and restrictions.
Industries Served Some of the industries we serve with our rubber to metal bonding and molding capabilities include the following:
- Alternative energy (hydrogen fuel cells)
- Automotive aftermarket
- Building and construction
- Industrial equipment
- Oil and gas
Rubber to Metal Bonding and Molding Solutions by Molded Products
The rubber to metal bonding and molding process allows manufacturers to combine the material benefits of elastomers and metals. Parts produced through this process generally demonstrate superior strength, flexibility, and durability. At Molded Products, we have over three decades of experience providing industrial customers with high quality, custom rubber molded products. If you need durable and flexible parts, we have the skills, knowledge, and full service machine shops to execute your project with precision. To learn more about our rubber to metal bonding and molding services or partner with us on your next project, contact us or request a quote today.