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Insert Molding Vs. Overmolding: What Are the Differences? 

Views: 329     Author: Site Editor     Publish Time: 2022-05-17      Origin: Site

Insert Molding Vs. Overmolding: What Are the Differences? 

Multi-material injection molding – especially over-molding and insert molding – is frequently used by manufacturers to create products that meet a variety of practical and aesthetic functions. The two methods are commonly confused since they have some commonalities, though there are several major differences.

Insert molding and over-molding are frequently misunderstood. Both procedures are injection molding that you use to generate structurally comparable items, which makes sense. However, a closer examination reveals that over-molding and insert molding are two separate processes with distinct benefits.

Insert molding and over-molding have numerous advantages, ranging from embedded electronics to enabling ordinary equipment easier to hold. However, you can only use these advantages if you know what makes those manufacturing methods distinctive.

What does Insert Molding entail?


Insert molding, like over-molding, is a subcategory of injection molding processes in which metal parts are put into a mold cavity well before the real injection of plastic. The insertion is manually or robotically positioned exactly in the mold. The mold is then closed, and the plastic is molded over the insert to form a single piece.

Metal connection elements for fasteners are among the most common uses for insert molding. Fasteners make it possible to install and dismantle components safely without damaging the product. To eliminate the possibility of thread breakage during installation, you mold the heat-set threaded inserts into plastic.

By integrating the appropriate metal elements in the mold, the insert molding can eliminate the need for the fasteners, firmly bonding the components into a single bonded component.

Benefits of insert molding?

  • It improves the parts' long-term durability. The plastic adds another protection layer, ensuring that the product lasts longer.

  • It's lighter since plastic may weigh up about half as much as the metal used to produce it. It makes it simple to use and transport.

  • It's a less expensive option because plastic is less expensive than a metal shell.

  • Design diversity. You may have your shell and metal piece shaped into whatever you wish. It distinguishes your products from the competition, exactly what you want.

What is Overmolding?


Overmolding is a form of molding. On the other hand, insert molding versus over-molding is when you mold plastic over another molded object, as the name implies. The initial component is created in an injection mold before placing it in a second mold to include the over-molded component. 

Multiple plastics are combined in this approach for either aesthetic or practical goals. To render a part simpler to grip, for instance, various durometer plastics could be used to form a gentler plastic over the more stiff one.

In an over-molded item, using several colored polymers will help to distinguish the product from various brands. Tool handles are frequently over-molded, such as screwdrivers, toothbrushes, and power drills.

Benefits of Over-molding.

  •  It aids in the enhancement of material adhesion. Overmolding tends to stay together better and is more seamless at the joints. The components will stay together longer than in any other way.

  •  It makes the design more concise. It's difficult to identify where one plastic chunk stops and the other begins. The seamless feature further enhances the piece's form.

  •  Low manufacturing costs. The overall process is mechanized, allowing for more merchandise to be stacked than if you use human labor.

  • It acts as an insulator. The pieces created are excellent insulators, a major benefit for most individuals.

Overmolding vs. Insert Molding: What's the Difference?


While over-molding and insert molding have many parallels in terms of applications, such as, education, energy, industrial, supply chain and purchasing, some variances exist. The following are the differences between over-molding and insert molding:



A two-production process is involved in over-molding. One process involves curing and molding the substrate, while the second involves molding an additional layer on top of the first. A two-step manufacturing procedure is not required for insert injection molding. It ultimately leads to the addition of yet another layer to a product.



Because both sections are developed independently, insert molding requires a while to mold additional items. As a result, it takes longer than over-molding. It involves whole product immersion in the molded part instead of partial encapsulation with over-molding.

Over molding helps to speed up the production process. It's achievable because the other piece does not need to be produced separately and may be molded directly into the product. 

Nevertheless, because over-molding is a complicated procedure, operators must follow specific guidelines.

Material selection


Over molding does not require adhesives. Over molding eliminates the need for adhesives, increasing part longevity and lowering assembly costs. As a result, the goods are typically long-lasting and adaptable. Because the critical metal pieces are incorporated in the mold, you don't need any mechanical fasteners during the insert molding process. Overmolded items are typically stronger than under molded products due to the materials.

Because the technique and consequences of over-molding are more complicated than single-shot injection molding, it's beneficial to obtain advice from resin specialists when choosing materials.



Insert injection molding decreases assembly costs significantly and allows for the production of thousands of parts in a single day. When producing in big quantities, insert injection molding prices drop dramatically. Overmolding, on the other hand, requires two steps and is a lot more costly than insert molding.

In general, the efficiency of insert-molded parts is inferior to that of metal parts. Overmolding improves material flexibility, and embedded seal over-molding allows a soft seal to be molded into the part.

Before deciding between the two procedures, you must consider the distinction between over-molding and insert molding. It will assist you in making well-informed selections. Before you settle on a production process, it's good to think about your applications. Certain over-molding parts might not be possible to make with insert molding or vice versa.

That is the distinction between these two molding procedures. Each has its own set of benefits and uses. It depends on the application and the parts that need to be made.

However, you might get assistance from a professional who can recommend the ideal injection molding procedure for your needs. All-win MFG is one such professional you can rely on.

With services including CNC machining, sheet cutting, sheet metal forming & injection molding, All Win MFG delivers 100% qualified products on time, efficiently and reliably. We are your ideal manufacturing partner for plastic parts, customized metal parts and customized sheet metal parts.

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