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Overmolding: A New Approach in Plastic Injection Molding

by Nice Rapid | May 05,2022 | Plastic Injection Molding

Have you heard about overmolding?

This is a unique injection molding process where two materials are seamlessly combined into a single part or product. The combination is usually a rigid, plastic-based component and overlaid with a pliable, thin, and rubber-like thermoplastic elastomer for its exterior. The process uses either single-shot (insert molding) or two-shot (multiple shot) techniques.

It is becoming increasingly popular among many manufacturers and has massive potential for industrial applications.

plastic injection molding parts

What are the types of overmolding?

There are many different types of overmolding and it all depends on the application and requirements of the project. In most cases, the substrate is harder and heavier than the covering material and the two parts are either chemically bonded or mechanically interlocked.

Here are the four different types of overmolding:

  • Plastic over plastic
  • Plastic over rubber
  • Plastic over metal
  • Rubber over metal

What are the best materials for overmolding?

There are two critical factors to consider when choosing the best materials for overmolding: compatibility and physical properties. The materials in the process should chemically bond, or else the product will fail or fall apart. You should also consider the outcome of the product.

Some of the most common materials include:

HDPE - High-density polyethylene is the most ideal material for durability and toughness. It can accommodate temperatures as high as 1830 F, therefore it is compatible with many applications. HDPE is also moisture resistant and can be processed quickly.

ABS - This is the most common material in overmolding because of its toughness, durability, heat resistance, and can work with acids and alkalis. The most common applications of ABS include electronics products, smartphones, and some automotive products.

PEEK - Polyethereketone is a material that can withstand the harshest environment. It is a great choice for applications that demand great thermal, chemical, and mechanical properties. It is commonly found in automobiles engines, gaskets, compressors, and other similar components.

Acrylic - This is another plastic that we see everywhere from optical lenses to touchscreens to lamps. Its surface is generally hard and has moderate tensile strength. It also offers great transparency and costs less than its counterparts.

Acrylic and PEEK are FDA-approved materials. Hence, they are suitable for use in the food and medical industry.

There are plenty of material options and combinations in overmolding. You must remember that it is important to get the right combination of materials to use in the process.

Advantages of Using Overmolding

Currently, there are plenty of sectors relying on an overmolding process to make their products safer, attractive, and practical. Here are some of the reasons why.

  • Better performance - one of the benefits of using overmolding is it can enhance the product's performance. You can find them in slip-resistant grips, soft handles, and other additional features.
  • Electrical insulation and vibration absorption - aside from enhancing its performance, overmolding can also make your product safer. It can help create insulated handles and covers to protect you from electric shocks and burns. It can also dampen vibrations in the source to give better protection and increase the durability of the product.
  • Reduce overall costs - the overmolding process can reduce cost and production times, thereby increasing efficiency and reducing the total running costs.


The competition is stiff in the consumer industry. It pushes manufacturers to be more creative to make their products stand out. Overmolding is an innovation in the injection molding process that can enhance the look and performance of a product.

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