Flexible Custom Overmolding

Yes, silicone can be overmolded, but the process requires careful design and control. Silicone is often overmolded onto thermoplastic substrates to enhance functionality, durability, or aesthetics.

Successful silicone overmolding depends largely on the chemical compatibility between the silicone and the base material. To achieve strong adhesion, surface preparation—such as cleaning, plasma treatment, or the use of primers—may be necessary. Additionally, precise control of temperature, pressure, and curing conditions is crucial to prevent damage to either material during molding.

When properly executed, silicone overmolding produces durable, flexible, and high-performance components, commonly used in medical devices, consumer electronics, and automotive applications.

Overmolding is a versatile manufacturing process in which a secondary material is molded over a base substrate to improve functionality, appearance, or user comfort. The selection of materials plays a critical role in achieving desired performance characteristics. Common materials used in overmolding include:

1. Thermoplastics:
Thermoplastics are widely used because of their excellent processability, toughness, and durability.

• Polypropylene (PP): Offers high chemical resistance and low density, making it ideal for lightweight components.

• Polyethylene (PE): Known for its toughness and impact resistance, often used in consumer and industrial applications.

2. Thermoplastic Elastomers (TPE):
TPEs combine the elasticity of rubber with the processability of plastics, providing a soft-touch feel and excellent flexibility.

• Styrenic Block Copolymers (SBC): A popular TPE family offering superior flexibility, surface grip, and strong adhesion to substrates.

3. Silicone:
Silicone is valued for its heat resistance, biocompatibility, and flexibility. It is commonly used in medical devices, wearable electronics, and consumer goods requiring high temperature stability and comfort.

4. Polyurethane (PU):
PU offers outstanding abrasion resistance, elasticity, and cushioning properties, making it suitable for automotive components, footwear, and protective coatings.

5. Rubber:
Rubber provides excellent grip, vibration damping, and resilience. It is often used in tool handles, grips, and other ergonomic products where comfort and control are essential.

Overmolding and insert molding are two advanced plastic manufacturing techniques designed to enhance product performance and design flexibility.

Process Definition:
Overmolding involves molding a secondary material over a pre-formed substrate, often combining materials with different properties to achieve benefits such as improved grip, aesthetics, or durability.
In contrast, insert molding places a pre-manufactured component—commonly metal, ceramic, or another plastic—into the mold before injection. The molten plastic then encapsulates the insert, forming a robust mechanical or chemical bond between the materials.

Applications:
Overmolding is widely used for ergonomic or aesthetic purposes, such as tool handles, electronic enclosures, or consumer goods where a soft-touch surface improves comfort and usability.
Insert molding is preferred in structural or functional applications, such as automotive, aerospace, and electrical components, where metal inserts or threaded parts need to be securely integrated into a plastic structure.

Design Flexibility:
Overmolding enables creative multi-material designs and enhances product appearance and user experience.
Insert molding, on the other hand, focuses on functionality and structural performance, ensuring strong bonding and precise positioning of inserts within the molded part.

Overmolding is an advanced injection molding process that seamlessly fuses two or more materials into a single, high-performance component. It allows manufacturers to combine the structural strength of a rigid substrate with the comfort, flexibility, or design appeal of a softer outer layer — all within one efficient production cycle.

The process begins by molding a core substrate, typically made from durable plastic or metal. Once this base is formed, a secondary material, such as a thermoplastic elastomer (TPE), is precisely overmolded onto the surface. The result is a strong, cohesive bond between the two materials, delivering both functional and aesthetic advantages.

With overmolding, products gain more than just a refined look — they benefit from enhanced grip, comfort, protection, and durability. By selecting the right material combinations, manufacturers can fine-tune performance characteristics like softness, chemical resistance, and color, achieving both technical and design excellence.

At Horizon, we harness this technology to help our partners create smarter, stronger, and more visually distinctive products. Our expertise in multi-material molding ensures seamless integration, precise alignment, and consistent quality from prototype to mass production.

Discover how Horizon’s overmolding solutions can transform your product design into a competitive advantage.