What is Overmolding? Definition, Process, Advantages and Disadvantages

Overmolding is a powerful and versatile manufacturing process that combines two or more different materials into a single part. Overmolding process is commonly used to create parts with a hard, rigid core and a soft, flexible outer layer.

In this article, we’ll see,

  • What is Overmolding?
  • Overmolding Process
  • Materials used in the overmolding process
  • Advantages of Overmolding
  • Disadvantages of Overmolding
  • Applications of Overmolding
  • How Topgrid can help you ?

What is Overmolding ?

Overmolding is a manufacturing process in which one material is molded over another to create a single part.

This process is commonly used to combine the properties of two different materials, such as the strength of plastic with the flexibility of rubber.

One of the most commonly used, everyday object toothbrushes is being manufactured by overmolding!

Overmolding Process

The overmolding process involves the following steps:


The base component, also known as the substrate, is molded using conventional injection molding techniques. The substrate is typically made of a rigid material such as plastic or metal.


The substrate is cooled and solidified. Then it is carefully prepared for the overmolding process. A release agent may be applied to ensure proper adhesion between the substrate and the overmold material.


The prepared substrate is placed into the overmolding mold. This mold is designed to accommodate the substrate and create the desired shape and features of the overmold.


The overmold material, commonly a rubber or thermoplastic elastomer (TPE), is injected into the mold. The mold cavity is carefully filled, ensuring that the overmold material flows around the substrate and adheres properly.


The mold is then cooled to allow the overmold material to solidify. This helps in forming a strong bond with the substrate. After cooling, the mold is opened. Then, the finished part is ejected.


The part is inspected for any defects or imperfections. Finishing processes such as trimming, sanding, or polishing may be performed to achieve the desired appearance and surface finish.

Material used in Overmolding

The materials used in the overmolding process can vary depending on the specific application and desired properties.

A few materials used are;

  • Thermoplastic Elastomers (TPE)
  • Thermoplastic Polyurethane (TPU)
  • Polyurethane (PU)
  • Silicone
  • Polyethylene (PE)
  • Polypropylene (PP)
  • Acrylonitrile Butadiene Styrene (ABS)
  • Polycarbonate (PC)
  • Polyethylene Terephthalate (PET)
  • Nylon (Polyamide)
  • Liquid Silicone Rubber (LSR)
  • Polyvinyl Chloride (PVC)
  • Ethylene Propylene Diene Monomer (EPDM)
  • Polybutadiene
  • Polyoxymethylene (POM)
  • Polyphenylene Sulfide (PPS)
  • Polyimide (PI)
  • Acetal
  • Thermoplastic Olefins (TPO)
  • Fluoroelastomers

Note: Always consult with a materials engineer or a manufacturing specialist to determine the most suitable materials for your specific application.

Advantages of Overmolding

Overmolding offers several advantages. This includes,

  • Overmolding can be used to create products with a comfortable and secure grip. It is particularly beneficial for tools, handles, and sports equipment.
  • Soft materials like rubber or silicone can be overmolded onto hard substrates like plastic or metal. This provides a non-slip surface that is easy to hold.
  • Overmolding can protect the underlying substrate from wear and tear. This helps in extending the products’ lifespan.
  • Overmolding can enhance the visual appearance of a product by adding different colors, textures, or patterns.
  • Overmolding allows for the integration of different material properties into a single component. This provides specific functional benefits like vibration damping, electrical insulation, or noise reduction.
  • Overmolding eliminates the need for mechanical assembly methods, reducing labor costs and improving production efficiency. This also eliminates the need for adhesives and fasteners.

Therefore these are the benefits of the overmolding process. There are a few limitations too. They are as follows.

Disadvantages of Overmolding

The overmolding process, though it offers several advantages, it also has some limitations or potential drawbacks that should be considered before choosing this method of manufacturing.

A few disadvantages of the overmolding process are,

  • Overmolding requires specialized equipment and tooling, which can be more expensive than traditional assembly methods.
  • There are a few material compatibility issues. Not all materials are compatible with overmolding. Some materials do not bond properly, leading to delamination or failure of the overmolded part.
  • Overmolding has limitations on part design, particularly for complex geometries or components with intricate features.
  • The two-step nature of overmolding can result in longer cycle times compared to single-shot injection molding.
  • Warping can occur due to the differential shrinkage of the two materials during cooling.

Overall, overmolding is an efficient manufacturing method that offers several benefits. However, it is important to carefully consider the potential drawbacks and assess their impact on the specific application before making a decision.

Applications of Overmolding Process

Overmolding finds its applications across various industries, offering enhanced functionality, durability, and aesthetics. 

Here are some common industries and products where overmolding is effectively employed

Consumer Electronics:

Overmolding provides a comfortable grip, and enhances impact resistance. It allows for the integration of multiple materials.

A few electronic devices such as 

  • Mobile phones
  • Remote controls
  • Wearable gadgets

are manufactured using overmolding.

Consumer Goods:

A few personal care products like,

  • Toothbrush handles
  • Razor grips
  • Hair styling tools

may feature overmolding.


Overmolding enhances both the tactile feel and durability of the part.

Therefore used in the manufacturing of,

  • Steering wheel grips
  • Gear shift knobs
  • Handles

and a few other interior components.

Medical devices:

The overmolding process contributes to improved ergonomics and hygiene.

Therefore employed in manufacturing medical equipment like,

  • Handles for surgical instruments
  • Grips for diagnostic devices
  • Specialized medical cables

Sporting Goods:

Overmolding helps in improving both the aesthetics and functionality of several sporting goods.

Therefore it is used in the production of sports equipment like,

  • Bicycle grips
  • Golf club handles
  • Fitness equipment

Toy Manufacturing:

Overmolidng adds a layer of safety by minimizing sharp edges. 

Therefore it is employed in the production of toys, creating soft and comfortable surfaces for handles and grips.

Due to its versatility, it is also used in manufacturing cable assemblies, aerospace products, industrial equipment, and many kitchen appliances.


In conclusion, the overmolding process is one of the most effective manufacturing techniques.

While it offers several advantages such as improved product aesthetics, enhanced functionality, and increased durability, there are a few drawbacks to consider. This includes cost implications, material compatibility, and increased complexity in design and production.

It is important to carefully consider the specific requirements of the end product and choose to employ overmolding.

How TOPGRID can help you ?

We TOPGRID, your manufacturing partner, offer you 50+ such manufacturing processes. You can choose as per your product needs. 

We’re dedicated to upholding the highest standards of quality throughout every stage of your manufacturing process.

From the initial design to the final product completion, we ensure the materials that undergo these processes and the products produced are quality-checked.

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