RJC incorporates in-house overmolding and inserts molding services to support our injection molding abilities. Many people confuse overmolding and insert molding since they have a bit of similarity.

However, the two are different processes but are related. Both processes are subsets or rather types of injection molding.

A similarity is that these methods involve the same process of molding, where you inject resin into a mold hole. A difference that can help you understand the two processes is that insert molding is not a subset of overmolding but vice versa.

Knowing the difference between insert molding and overmolding will make it easier to choose the right process to use in manufacturing a product.

What Is Overmolding

Overmolding is an injection molding process that involves multistage, which involves molding two or more components on top of each other.

In molding, another layer is placed on the top first layer and molded into one. Since overmolding involves a two-step process, it is sometimes referred to as two-shot molding. Overmolding involves two main processes making the process affordable and fast.

The process of overmolding

The first step involves molding a substrate and allowing it to cure. The common material used for overmolded substrates is plastic.

The second layer is placed on top of the first layer and molded into a single piece. An example of the two-shot process is creating a toothbrush.

The handle base is formed separately and then attached using the overmolding process. The base is fitted with a rubbery surface to reduce slipping.

Overmolding is used in various materials such as nylon, silicone, polypropylene, thermoplastic rubber, acrylic, ABS, and others.

What Is Insert Molding

Insert molding is a form of injecting molding, but the second part is formed over the substrate. A structural difference between insert molding and overmolding is that insert molding has a preformed substrate or base. The preexisting substrate is placed in the mold, and then the second layer is formed to encapsulate it.

The most common insert molding process is adding a plastic part to a metal component such as a screwdriver. The screwdriver has a plastic part covering the metal part to form a handle. Other tools employ insert molding techniques when creating electronics embedded into plastics, insulated water pipes, and similar products.

The same materials used in the overmolding process are also utilized for this process.

As seen above, overmolding and insert molding are close, but the differences are visible when you understand the processes in depth. Most of the businesses prefer alternatives of overmolding since it takes longer to get a turnaround.

All types of overmolds can be termed insert mold since the process is similar in some ways. However, not all insert molds can be over molds because the structure and process are different.

Benefits of Overmolding

It significantly reduces the number of steps required to create the end product. It is called two-shot for the reason that it uses only two steps. Other molding methods may require more steps which leads to a higher cost of production. Hence over-molding is effective if you want to cut costs.

The finished look of a product that has undergone overmolding is attractive and includes color schemes for appeal.

Thus making it has a competitive advantage over other products. It is important to have products with unique features that make them stand out in other products. It is a marketing strategy used by many shop holders.

Most of the products that undergo this process have a non-slip grip to control dropping. The rubber grip also functions as a barrier for shock, noise, and vibrations from the environment to increase the product’s service life.

Overmolding has a limitation that is important to be aware of before deciding to choose it.

Just like the mother, inject molding overmolding has high starting costs. It is expensive and drains to create and change the structure of tools out of metal.

Thus, for you to make a profit, you have to consider mass production. Mass production brings huge profits to overwrite the costs incurred in the forefront.

Benefits of Insert Molding

It reduces the parts required and sets the logistics regarding shipping, tracking, supplier consolidation, and shipping.

It eliminates secondary processes during assembly, e.g., using screws, gluing, fasteners, and snap fits—fusing design features that cannot be done by plastic features alone and including important metal parts.

The downside of insert molding is similar to the ones of overmolding. Although when you decide to manufacture insert molding tools without a 3D printer, get ready to experience many challenges. The parts and tools for insert molding have to be precise. The base has to be in suspension in the mold to create a final product.

How To Decide Whether Overmolding or Insert Molding Is Appropriate for Your Project

It may be challenging to decide whether to use overmolding and insert molding. But worry not, we have compiled a list of scenarios where you will need either of the methods.

Scenarios You Need To Choose Over-Molding
  • When you are manufacturing everything from scratch, both the second layer and substrate
  • You will use overmolding if the finished product does not need to be taken apart
  • If your end product is made of rubber or thermoplastics, you will use the over-mold technique.
  • Use the overmolding process if the end product design will have multiple layers and materials.
Scenarios You Need To Use Insert Molding
  • You will have to use the insert molding process if the substrate is prefabricated
  • If your preformed part is made of computerized parts, wires, and metal, choose insert molding
  • If the condition of your finished product is to have a single piece


At RJC, we used insert molding and overmolding to produce a variety of products for many industries. We have a team of engineers who are experienced in using molding techniques. Before you decide to create a given product, our engineers will advise you on the best way to go about it. Some products we manufacture in our premises are as follows.

Automotive Industry

Insert molding is used to manufacture fasteners, gears, and other automotive parts that combine rubber, plastic, and metal.

We use the overmolding technique to create two-tone interior parts such as handles, knobs, and control parts.

Medial Industry

Plastics are easier to sterilize than metal, so the medical industry relies on overmolded and inserts molding.

The medical industry depends on many items through insert molding, such as the pacemaker implanted in the human body. Insert molding helps manufacture cameras utilized in internal imaging in the human body.

Electrical Industry

Insert molding and overmolding are used to manufacture insulated electrical wires making the wires safer and element-proof.

We coat the components of the wire with rubber-like materials for the safety of human beings, e.g., computer chargers.

We use the accepted code of colors when it comes to differentiating different types of wires. It is very important to color code to easily tell which one is hot and which one is neutral.

Beauty Industry

The beauty industry is one of the areas where we utilize the two techniques. We routinely use internal molding and over-molding to make the packaging of beauty products attractive.

Designers can now create a package with custom features such as texture and colors. We have produced all of the following products, e.g., perfume, compacts, and compacts.

Consumer Goods

RJC produces products that are mostly used in everyday life. Just swirl around your sitting space and look at the things around you.

Most of the products you see were created through the overmolding process. The method is very popular and is used to create anything from plastic containers, plates, children’s toys, and so much more.

Co-Injection Molding

Co-injection molding is the most expensive type of molding of the three molding processes. The creation process is different since it involves injecting the elastomer and substrates in a molding process. Materials used in this process must be compatible with each other.

Final Thoughts

Choosing injection molding to create a certain part for your industry is not the final point of the decision. Well, you have to decide whether to use over-molding and insert molding for your project.

Suppose you do not know what to choose; you can stick to traditional types of injection molding. However, if you feel you need to choose between one of the two and have no experience, please get in touch with RJC engineers on the topic.

Our company is happy when you get into contact with the staff to know more about a product. We are ready to support any person to know more about injection molding and its other subsets.

The forefront costs of producing to produce using the overmolding process are very high. Here is where RJC walks in to assist you in saving more money for an easier payment structure. We have a specialized series of steps that you can easily follow if you need to order with us.