Aria provides design assistance and material selection guidance to help customers optimize their overmolding projects for cost, performance, and manufacturability.

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Finished Overmolding projects


Injection Mold Design

Overmolding Design

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Experience in overmolding

15 years

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Overmolding Cost

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Types of  Overmolding Process

Overmolding can be used to improve the strength, durability, and aesthetics of a plastic part. It can also be used to add functionality to a part, such as adding a grippy surface or creating a water-tight seal.

Plastic Over Plastic
Plastic Over Plastic

A second layer of plastic is added to the core part. This can be used to improve the strength or aesthetics of the part.

rubber over plastic
Rubber Over Plastic

A layer of rubber is added to the core part. This can be used to improve the grip of the part or create a water-tight seal.

plastic over metal
Plastic Over Metal

A layer of plastic is added to a metal core. This can be used to improve the durability or aesthetics of the part.

rubber over metal
Rubber Over Metal

A layer of rubber is added to a metal core. This can be used to improve the durability or grip of the part.

How does overmoling work?


The overmolding process begins with a mold that has two halves. The first half of the mold is filled with the first material, and the second half is filled with the second material. The two materials are then injected into each other, bonding them together.

The basic items used for Over Molding have been classified into two types – the first one being the substrate, and the second one being the Over Molding material. The substrate may be composed of glass, plastic, metal, or rubber. Whereas the other item is commonly thermoplastic. When these two are combined, their adjoining can be the cause of a mechanical interlock or a chemical bond between the two. Either way, the parts create a new object, for example, scissors, cellphones, drill machines, etc.

Using Overmolding technology reduces the assembly process and manufacturing cost, improves product quality and performance, enhances the appearance and molding, and improves competition for the product.

What is Overmolding Process?

Our overmolding allowing you to create parts that meet your specific needs and requirements. With advanced materials, injection molding expertise, and secondary operations, we can help you create high-quality overmolded parts quickly and cost-effectively.

1. Molding Core Part

The first step is to create the core part using injection molding. This part will be the innermost layer of the overmolded part.

2. Create Overmold Layer

A second mold is created that is slightly larger than the first mold. This second mold will be used to create the overmold layer.

3. Assembly

Molten plastic is then injected into the second mold. This plastic will flow around the core part, and fill the entire mold.

Injection Mold design

4. Cooling & Demould

Once the overmold layer has cooled and hardened, it can be removed from the mold. The overmolded part will now have two layers of plastic!

Overmolding Plastics

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ASB Materials


ABS (Acrylonitrile Butadiene Styrene) is a common thermoplastic polymer that is widely used in a variety of applications, including automotive parts, toys, and electronic housings. ABS materials offer excellent impact resistance, dimensional stability, and high tensile strength.

ABS materials are a versatile and reliable choice for overmolding applications due to their excellent mechanical and chemical properties, ease of processing, and cost-effectiveness.

Nylon Materials


Nylon materials have a high melting point, which makes them suitable for overmolding onto substrates with high melting points, such as metal or glass.

and it have a certain degree of flexibility, which can be useful for overmolding applications where the molded part needs to be able to bend or flex without breaking.

PC Materials


Polycarbonate is a very durable material that can withstand shock and high temperatures. It is also resistant to chemicals and wear and has good adhesion and can easily bond to other materials during the molding process.

On the other hand, Polycarbonate can be easily molded into complex shapes, allowing for greater design flexibility. This makes it suitable for overlay applications where precise shapes are required.

PE Materials


According to the density, there are 2 types of PE: LDPE and HDPE. It has good inherent lubricity and is easy to process. It should be noted that it is very soft and cannot be used at a temperature much higher than 150.

PE materials are resistant to a wide range of chemicals, making them suitable for overmolding in applications where the final product may come in contact with chemicals or other corrosive substances.

PP Materials


Polypropylene has a high level of flexibility and toughness, which makes it ideal for overmolding applications where the parts need to withstand impact or other forms of stress.

PP is a cost-effective material compared to other engineering plastics, making it a popular choice for overmolding applications where cost is an important factor.

PP Materials


PMMA stands for Polymethyl methacrylate, which is a synthetic polymer that is also known by the trade name of acrylic or acrylic glass. It is a transparent and rigid thermoplastic material that is widely used in various applications due to its unique properties.

PMMA is an excellent choice for overmolding due to its unique properties and benefits, including transparency, high strength, chemical resistance, aesthetics, and UV resistance.

POM Materials


POM has a low coefficient of friction, which makes it an excellent choice for overmolding products that require smooth movement, such as gears and bearings.

And it has good resistance to high temperatures, making it an excellent choice for overmolding products that will be exposed to high temperatures.

HIPS Materials


HIPS is a thermoplastic polymer known for its excellent impact resistance, making it an ideal choice for products that may be subjected to frequent impacts or drops.

HIPS is a light weight material with good impact resistance is an ideal material for Overmolding products requiring durability and impact resistance. The product also has a good surface finish.

PU Materials


PU(Polyurethane) is an extremely elastic, wear-resistant, and tear-resistant elastic material that can be used in ether and ester-based formulations. These different formulations cover a very wide range of hardness and density.

Polyurethane (Pu) materials are known for their flexibility and elasticity, which make them ideal for overmolding applications where parts need to be able to bend and flex without breaking.

TPE Materials


Thermoplastic polyurethane (TPU) can be easily overmolded onto a variety of substrates, including plastics, metals, and rubber. This allows for a wide range of design possibilities and can create a strong bond between the two materials.

In overmolding, The TPE should be less thick than the substrate to prevent warpage, especially if the part is flat, long, or both.

Notes On Material Selection


Some materials stick together when they are overmolded, while others do not. Perfect combination is the ideal situation.

Tensile property

Since it is overmolded on plastic, the substrate must not deform under the heat and pressure of the molding process.

Compression Properties

It may be important for your overmoling project to know how much parts can be compressed without permanent damage.

Friction Coefficient

Friction is the force required to cross one surface over another, The surface texture of the mold is a factor too.


Hardness property is the ability of the material to resist indentation, hardness of different materials vary greatly.

Flexural properties

The bending resistance of a material is the bending modulus. This attribute is the second factor in the “feel” of materials.


From a design point of view, the thickness of the material will change the effectiveness of the material properties.

Applications of Overmolding Services

This technique is widely used in various industries to improve product performance, enhance the aesthetic appeal, and provide additional functionalities to the end product.



Consumer Goods

Medical Devices

Electronic Component

Advantages of Overmoding Servcies

There are a handful of reasons for its preference over the other molding processes. After closely evaluating each one of them, we’ve come up with some of the most impressive advantages of Overmolding for the plastic manufacturing industry.

injection molding surface quality

Performance of parts improved

The overall performance is hence increased because the user has better control of the tool due to the addition of a rubber substrate.

reucing tooling cost

Reduces cost of parts

As this method is a single cycle process, This increases their production rate, and the customers receive the final item faster!

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Excellent shock absorption 

Overmolding is used to provide plastic resins on the product.  the user may feel a reduced shock and vibration when the products is used.

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Elegant structure and design

Elegant structure is a very important factor in product competitiveness, because it immediately catches the eye of the buyers. 

Plastic Injection Overmolding FAQs

Overmolding is a process where two or more different materials are molded together to create a single product.

In the case of plastic overmolding, one of the materials is typically a plastic. The other material can be another plastic, metal, rubber, or even glass.

The primary difference between them is that, in overmolding, the plastic material is injected directly onto a molded part or assembly; in insert molding, the plastic is first injected into a cavity and then the finished piece is inserted into another injection-molded part.

Overmolding can reduce production costs. While standard injection molding can combine multiple parts into a single multi-cavity mold, secondary molding can produce individual parts made of different materials without assembly. Mold production is more complex, but it eliminates the repetitive cost of assembling thousands of parts.

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