Overmolding Services: Enhancing Product Performance

Overmolding services have revolutionized the manufacturing landscape by introducing innovative techniques that combine different materials to enhance product functionality and design. This process involves molding one material over another, often plastic over metal or plastic over plastic. In this comprehensive exploration of overmolding, we will explore the advantages and common application cases, and provide insights into the overmolding of plastic and metal parts. Additionally, we’ll explore the methods employed in overmolding plastic and metal components, shedding light on the common plastic and rubber materials used in this intricate process.

What Is Overmolding?

Overmolding, also known as two-shot molding or multi-material molding, is a specialized manufacturing process that involves molding one material over another to create a single, integrated product. This technique offers a versatile solution to product design challenges by combining materials with distinct properties. Overmolding is not limited to specific material combinations; however, it often involves molding plastic over metal or plastic over plastic. The process aims to achieve a seamless integration of materials, resulting in a final product that is not only functional but also aesthetically pleasing. Overmolded products often exhibit improved durability, ergonomic designs, and enhanced aesthetic appeal compared to traditional single-material products.

Advantages of Overmolding

Overmolding offers a plethora of advantages, making it a preferred choice in various industries. Some key benefits include:

  1. Enhanced Aesthetics:

   Overmolding allows for the incorporation of multiple colors, textures, and materials, enhancing the visual appeal of the final product. This is particularly beneficial for consumer goods where aesthetics play a crucial role.

  1. Improved Ergonomics:

   The ability to mold soft, rubber-like materials over rigid components enhances the ergonomics and comfort of products. This is often seen in the design of handles, grips, and other surfaces that come in direct contact with users.

  1. Increased Durability: 

   Combining materials with different properties can result in products with improved durability and impact resistance. Overmolding reinforces critical areas, reducing the risk of damage or wear under challenging conditions.

  1. Cost-Effective Manufacturing:

   Overmolding can streamline the manufacturing process by creating a single, integrated component instead of assembling multiple parts. This can lead to cost savings in production, assembly, and overall material usage.

  1. Seamless Integration of Components: 

   Overmolding enables the integration of different materials without the need for secondary assembly processes. This seamless integration enhances the overall structural integrity of the final product.

Common Application Cases of Overmolding

Overmolding finds application across various industries, providing innovative solutions to diverse manufacturing challenges.

At Sung Precision Mould & Plastic Co., Ltd, since 2002 we have delivered high quality plastic injection molds and services including: plastic injection molding, custom injection molding, prototype injection molding, overmolding, insert molding and more. We leverage our technical knowledge of the injection molding process and materials, customer service and responsiveness to our customer needs, and our focus on quality and reliability to make us stand out in our industry. If your business is looking for a plastic mold manufacturer and injection molding supplier, please contact us with your inquiry of injection molded parts.

Some common application manufacturing cases include:

  1. Consumer Electronics: 

   Overmolding is extensively used in the production of consumer electronic devices, such as mobile phones, remote controls, and wearable devices. This allows manufacturers to achieve sleek designs, comfortable grips, and improved durability.

  1. Medical Devices:

   In the medical field, overmolding is employed to create ergonomic handles for surgical instruments, comfortable grips for medical devices, and components with enhanced chemical resistance.

  1. Automotive Components: 

   Overmolding is applied in the automotive industry to create soft-touch surfaces for steering wheels, gear shift knobs, and handles. This enhances the user experience and contributes to the overall aesthetics of the vehicle interior.

  1. Tool Handles and Grips: 

   Tools with overmolded handles and grips benefit from improved ergonomics and user comfort. The overmolding process allows manufacturers to design handles with contours that fit comfortably in the user’s hand.

  1. Industrial Equipment: 

Overmolding is utilized in the production of various industrial equipment components, providing improved impact resistance, durability, and ergonomic features.

How to Overmold Plastic Parts?

Overmolding plastic parts involves a meticulous process that requires precision and expertise. The general steps for overmolding plastic parts are as follows:

Material Selection:

Choose the appropriate materials for the base and overmold components. Consider the compatibility of materials in terms of adhesion, thermal expansion, and overall performance.

Mold Design: 

Design the molds for both the base and overmold components, ensuring that they align accurately during the molding process. The molds must accommodate the specific geometry of the parts and allow for proper material flow.

Insert Placement:

If using inserts (metal or plastic components), position them within the mold for the base material. The inserts will be encapsulated by the overmold material during the molding process.

Injection Molding: 

The base material is first injection molded into the mold. Afterward, the mold is opened, and the overmold material is injected over the base material. The overmold material bonds with the base material during this stage.

Cooling and Ejection: 

Allow the combined structure to cool and solidify within the mold. Once cooled, eject the overmolded part from the mold.

How to Overmold Metal Parts?

Overmolding metal parts involves similar steps as overmolding plastic parts but requires additional considerations due to the differences in material properties. The steps include:

Material Compatibility: 

Ensure compatibility between the metal part and the overmold material. This includes addressing issues such as thermal expansion differences and adhesion.

Surface Preparation: 

Properly prepare the surface of the metal part to facilitate adhesion with the overmold material. Surface treatments or coatings may be applied to enhance bonding.

Mold Design: 

Design molds that accommodate the metal part and allow for precise alignment with the overmold material. Considerations for thermal management are crucial due to the different cooling rates of metal and plastic.

Insert Placement: 

Position the metal part within the mold for the base material, taking care to ensure proper alignment. The metal part will be encapsulated by the overmold material during the molding process.

Injection Molding: 

Follow the injection molding process, starting with the base material injection and followed by the overmold material. The overmold material bonds with the metal part during the molding process.

Cooling and Ejection: 

Allow the combined structure to cool and solidify within the mold. Eject the overmolded metal part from the mold.

Common Plastic and Rubber Materials Used for Overmolding

The success of overmolding relies on selecting materials that complement each other in terms of adhesion, mechanical properties, and overall performance. Common plastic and rubber materials used for overmolding include:

Thermoplastic Elastomers (TPE): 

TPEs are versatile materials that combine the properties of rubber and plastic. They offer excellent flexibility, softness, and durability, making them suitable for overmolding applications requiring comfortable grips or soft-touch surfaces.

Thermoplastic Polyurethane (TPU): 

TPU is known for its high elasticity, abrasion resistance, and chemical durability. It is commonly used in overmolding applications where flexibility and toughness are essential, such as in the production of shoe soles and handles.

Liquid Silicone Rubber (LSR): 

LSR is a flexible and heat-resistant material that can be overmolded onto various substrates, including plastic and metal. It is often used in medical devices, consumer electronics, and automotive components.

Polypropylene (PP): 

PP is a widely used thermoplastic that provides good chemical resistance and toughness. It is suitable for overmolding applications requiring a durable and rigid base material.

Acrylonitrile Butadiene Styrene (ABS):

ABS is a common thermoplastic known for its impact resistance and dimensional stability. It is suitable for overmolding applications where a rigid base material is desired.

Polyamide (Nylon): 

Nylon offers high strength and resistance to wear, making it suitable for overmolding applications in which durability is a key requirement. It is often used in automotive and industrial components.

Polycarbonate (PC): 

PC is a transparent thermoplastic with excellent impact resistance. It is used in overmolding applications where optical clarity or transparency is necessary.


Overmolding services represent a pinnacle of innovation in manufacturing, allowing for the seamless integration of different materials to create products with enhanced functionality and design. Whether overmolding plastic over metal or plastic over plastic, the process offers a myriad of advantages, including improved aesthetics, ergonomics, and durability.

Understanding the intricacies of overmolding plastic and metal parts, along with the selection of suitable materials, is crucial for achieving successful outcomes. Overmolding manufacturers continue to leverage overmolding services to push the boundaries of product design, offering consumers products that not only meet functional requirements but also exceed expectations in terms of comfort and visual appeal. In a world where differentiation is key, overmolding stands as a beacon of innovation, shaping the future of manufacturing in diverse and exciting ways.

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