Rubber overmolding is a unique process that allows us to mold different rubber materials “over top” of a metal or plastic substrate. Essentially, that means your end products receive the advantages of both materials: high strength, structure, and rigidity from the underlying substrate, combined with a rubberized surface that absorbs impacts while being softer and more pliable – typically to achieve better ergonomics.
For example, it’s common to overmold soft rubber handles onto metal tools and handheld plastic devices to improve grip and comfort. The rubber overmold can also help protect these products, functioning as a shield with excellent shock absorption properties. For high-performance seals, we can combine the durability of metal with the outstanding sealing properties of silicone or other rubbers – as seen in our Self-Sealing Washers. These are just a couple of the highly customizable product applications.
Panova’s custom rubber overmolding services enable us to manufacture complex multi-material components that meet unique functional requirements and performance targets. In many applications, these requirements would be impossible to achieve with a single molded rubber or molded plastic material.
An Overview of the Rubber Overmolding Processes
As we discussed in our previous article, there are three processes we primarily use to manufacture custom molded rubber products: injection molding, transfer molding, and compression molding. Likewise, these three processes can be used for overmolding rubber.
Overmolding in Rubber Injection Molding
The substrate is placed into the mold cavity before the injection molding process begins. Uncured rubber is then injected into the mold, which fills the remaining space around the substrate. As the rubber heats and cures, a strong bond forms between the injected rubber and the substrate.
Overmolding in Rubber Transfer Molding
The substrate is placed into the mold cavity before the transfer molding process begins. A premeasured amount of rubber material is heated in a pot atop the mold. A piston forces the uncured material into the mold where it surrounds the substrate while it cures and bonds.
Overmolding in Rubber Compression Molding
In compression overmolding, a preformed rubber blank is placed into the mold cavity along with the substrate. The mold is closed, and heat and pressure are applied. The rubber conforms to the shape of the mold and bonds to the substrate. This process is often ideal for exceptionally hard or difficult-to-flow rubber materials.
The Advantages of Rubber Overmolding:
Bonding Rubber to Metal Substrates and Inserts
From metal hand tools to high-performance industrial seals, many products demand the material advantages of metal and rubber. Rather than having to compromise on performance, or otherwise assemble multiple components, rubber overmolding creates a single, solidly built component out of the two materials. That eliminates the need for complex assembly processes, fasteners or press-fit operations, while also creating a more robust end product.
Bonding Rubber to Plastic Substrates and Inserts
Likewise, many modern products demand the functional performance of rigid plastic materials with a softer, more pliable rubber overmold. End product applications include everything from specialized industrial electronics to everyday consumer products like mobile devices, toothbrushes, and other handheld utensils. By combining plastic injection molding capabilities with rubber overmolding, Panova can manufacture almost any custom plastic part for use as a substrate, giving you virtually endless product possibilities.
Bonded Rubber-to-Metal Seals
Many high-performance seals (e.g. for industrial use or aerospace applications) require increased strength and performance over conventional rubber seals. Our overmolded rubber/metal sealing washers provide metal-to-metal contact upon installation for a precision fit when extremely close tolerances must be maintained. In use, the metal substrate protects internal rubber sealing elements from damage to promote better long-term reliability.
Other Common Overmolded Rubber Product Applications:
- Automotive Components – Handles, shifter grips, steering wheels, and other interior components as well as seals and gaskets for the engine, exhaust, and emissions systems.
- Electronics Devices – Device housings, keypads, buttons, and various ergonomic features.
- Medical Devices – Device housings, handles, other ergonomic features, as well as specialized medical seals.
- Consumer Products – Hand tools, power tools, appliances, kitchen tools and utensils, sporting goods, and other common household devices.
Comprehensive Rubber Molding Solutions Since 1977
Panova offers comprehensive molding capabilities for custom rubber products – including overmolding and insert molding for complex multi-material components.
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