Insert Molding Services

Insert rubber molding is a unique manufacturing method that enables manufacturers to integrate metal or thermoplastic substrates or inserts into a rubber molded component. Metal and plastic insert rubber molding supports a range of design options while offering enhanced functionality and superior durability.

RD Rubber Technology Corporation is a leading insert rubber molding service provider with over 35 years of experience delivering quality engineered products. We offer custom solutions for demanding applications, leveraging sophisticated technology and deep expertise to realize critical to function products for industry’s most demanding applications. We are widely recognized as a leader for delivering engineered quality that meets our customers most demanding requirements.

What Is Insert Molding?

Insert rubber molding delivers a superior bond between components. In this process, metallic or thermoplastic substrates are molded with high performance synthetic rubbers to produce a single integrated component. Insert rubber molding is ideal for creating assemblies with high structural integrity.

The Insert Molding Process

Rubber insert molding follows several steps, including:

1. Identify the Right Elastomer: Natural and synthetic rubbers can both be bonded to metal substrates, but they require different preparation methods and are paired with different fillers to give the material new characteristics. At this stage, the rubber does not exhibit its desired properties until it is cured in the molding process.
2. Preparing the Metal Surface: After deciding on the proper elastomer material, manufacturers prepare the surface of the metal substrate. First, the surface needs to be thoroughly cleaned with a degreasing solvent and stored away from moisture. If the parts need to be handled manually, technicians should wear gloves or use a cloth so the parts are maintained in pristine condition.
3. Applying Primer and Adhesive: Once the metal is cleaned, manufacturers apply either a one-step adhesive coating or a two-step primer and adhesive coating. RD Rubber’s chemical bonding solutions comply with ASTM D429 standards.

   Chemical adhesives are applied through dipping, rolling, spraying, or brushing the substrate. The ideal thickness for the primer should be about 0.2 to 0.4 mil and 0.5 to 1.0 mil for the adhesive. The coating then needs to dry and set in a low-humidity environment free of contamination.

   RD Rubber also performs mechanical bonding, in which rubber materials flow through channels or holes in the metal substrates. This creates a strong rubber bonding to metal on its own or assists the chemical bonds to stay intact over time.

4. Molding: After the adhesive application, the molding stage should take place as soon as possible. A common molding technique is rubber compression molding, which is a closed mold process that produces low to medium volumes of rubber to metal bonded components. Compression molding involves positioning an uncured rubber preform or profile into a heated mold, which applies high clamping pressure to fill the cavities with the rubber material. The rubber takes the shape of the mold and is cured into a finished molded component. Once the part finishes curing, technicians cut off excess material and set aside the bonded parts.
5. Testing: After molding, the parts are tested to ensure the bond, tensile strength, and other properties meet customer specifications. Manufacturers also test the components according to the standards established in ASTM D429. Common performance modes to test include 1) the strength of the rubber and adhesive bond, 2) the strength between the primer and adhesive layer, and 3) the strength between the adhesive and the metal.

Insert Molding vs. Overmolding

Overmolding and insert molding both combine distinct materials. However, there are several differences to consider when choosing one of these methods for use in a manufacturing project:

• Insert molding delivers superior durability and strength by integrating the insert with the injected rubber or plastic material
• Overmolding produces an additional layer of molded material over an existing component
• Insert molding is preferred for producing integrated components with improved durability
• Overmolding is a superior solution for introducing secondary features to a component, offering a flexible option for a breadth of manufacturing projects

The Unique Benefits of Insert Molding

Insert molding delivers several notable benefits, including:

• Improved product durability and strength (due to its integration with different materials) for a robust and solid finished product
• Increased flexibility, which can be leveraged to create multifunctional parts and complex geometries for various project requirements
• Enhanced assembly process that produces a single integrated product.

Advantages of Choosing RD Rubber for Insert Molding

When you choose RD Rubber for your insert molding solutions, you will benefit from our expertise in insert molding and extensive industry knowledge. We maintain the following certifications and registrations:

• ISO 9001:2015 certified
• AS 9100:2016 certified
• ITAR Registered
• DOD Registered
• NIST 800-171 compliant

Our team delivers coordinated support with your team members from the initial design phase and prototyping to final production, all the while providing consistent communication to keep you up to date on your project and delivery status.

Get Started With RD Rubber’s Insert Molding Services

Insert molding delivers superior product functionality and durability by encapsulating metal or plastic inserts in high performance synthetic rubber compounds. Insert molding can be rapidly completed with fewer processes than conventional assembly options to produce a single component with enhanced structural integrity.

RD Rubber Technology Corporation is ready to improve your product’s reliability and performance with our custom insert molding services. Contact us or request a quote to speak with an expert about our full capabilities.