Custom Overmolding Insert Injection Molding Services

Zhongde, a reputable plastic and rubber injection molding company in China, provides insert and over-molding services and produces unique multi-material parts.

Both over-molding and insert molding injection processes by Zhongde, a reliable injection molding supplier, involve putting two types of materials together to make one part, and the inserts can be threaded metal inserts. Overmolding is a two steps process, one to create the substrate and one for the oversold that goes on top of it. China inserts molding is a slightly faster process as it takes only one step that the two materials are molded at the same time.

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Overmolding vs Insert Molding

Overmolding is a process where a single part is created using two or more different materials in combination. Traditionally, over-molding starts with injection molding a hard plastic resin that has a higher melting point. Once that part is cooled, another material is injection molded over the first part, resulting in a single, finished product.


Insert molding combines metal and plastic injection molding services into one single part. It allows the plastic to bond to insert pieces, mostly brass or stainless steel metal component, which go inside a mold cavity. There are many options for the insert that can be placed into the mold. A few examples are warming labels, threaded bushings, wires, batteries, etc.

Injection Molding From Prototyping to Production

Injection Molding Molds Making and Tooling Services

Zhongde, a custom plastic injection molding company in China, can produce the most intricate CNC injection mold, which is up to 78 inches long. In addition, our customize plastic die mold is lifetime guaranteed and machined from high-grade metal.

We have been insisting on developing our own molds for many years, meanwhile, introducing fully automated equipment. Our professional engineer will help to improve the mold design.

  • Injection Molding Service Option: Prototyping & on-demand manufacturing


  • Mold Material: Steel P20, H13, S136, 2316,2344, 083, 718H, SKD618, etc.


  • Mold Type: Family molds, single and multi-cavities molds


  • Mold Storage: Stored for 3 years in inactivity


  • Guaranteed mold life: Unlimited


  • Mold Remachining: We can re-machine the molds if there are any changes required, basis on mold structure.

Size of Over Molding and Insert Molding Parts

Below table shows the size of Overmolding & Insert Molding parts we usually make. If you need a larger size, we can also help you achieve it.

Size Metric Inch
Length 2500 98.4
Width 2000 78.7
Height 1500 59

What Materials Are Used in Overmolding and Insert Molding?

In addition to the general materials listed below, Zhongde, a reliable custom rubber injection molding company, can also modify the materials according to the special needs of customers. Our professional engineers will adjust the raw material formula to meet the unique conditions of use. Our production materials for custom over-molding and insert molding range from thermoplastic to elastomer rubber, as well as metal and silicone. We’ve broken down the differences and similarities between the two processes. Let us help you decide which process is right for your project.

The General materials listed below are for custom insert and overmoled plastic injection.


The general rubber overmolding & insert molding materials are listed below:


The metal over molding and insert molding with metal inserts are listed below:

AluminumStainless Steel
Carbon SteelCopper

Injection Molding Surface Finishing

Injection molding surface finish is critical to a successful part design and it is used for aesthetic and functional reasons in injection molded parts for engineering products. The surface finish improves the look and the feel of a product as the perceived value and quality of the product increase with a suitable surface finish.

Different grades of surface finishing chart.

GlossyA-grade finishes are made using a diamond buffing process and yield shiny and glossy surfaces on injection molded parts.Get A Quote
Semi-glossyB-grade finishes use grit sandpaper to produce parts with a slightly rougher finish than grade A parts. Custom molded plastic parts that undergo B-grade finishing have a matte surface texture.Get A Quote
MatteC-grade finishes use grit sanding stones to produce a rough, uneven surface. Injection plastic parts that undergo C-grade finishing have a matte surface texture.Get A Quote
TexturedD-grade finishes use grit and dry glass beads or oxide to produce a very rough textured finish. Depending on the type of material used, products can have a satin or dull finish.Get A Quote

What is the diferent of overmolding and insert modling?

What is Overmolding?

Overmoulding is a manufacturing process that involves molding a material over another material or substrate to create a single part. It includes placing a pre-formed material or substrate, such as a metal component, into a mold cavity.

What is Insert Molding?

Insert molding is a form of injection overmolding. The only difference between overmolding and insert molding is that the pre-formed part is added to the mold before pouring the molding material. The material flows around and between the pre-formed substrate to form a finished product that has better durability and strength than an overmolded component. In overmolding the material is molded over another material. An example is the rubber part of the toothbrush.

overmolding process

Insert Molding and Overmolding Types

There are many kinds of overmolding and insert molding, including plastic over plastic, plastic over metal, rubber over metal, and rubber over plastic. Dividing the materials of the mold, there are two kinds of overmolding – plastic overmolding and rubber overmolding.

The below Images show the different types.

Bonding The Resin to the Metal


Metal Insert into the Resin


Rubber Onto Plastic


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Related Products of Overmolding & Insert Molding

Rubber Roller

Anti Vibration Mount

Rubber Brake Pedal

Rubber Feet

Rubber Impeller

Suction Cup

Click and get a thorough description of the process of overmoulding and a breakdown of the cost factors.

Why Choose Zhongde for Custom Injection Molding?

Moving beyond rapid prototyping, this reliable injection molding manufacturer is supported by many senior project managers and engineering experts, communicating through all project stages from design to production.

FAQs of Insert Molding & Overmolding

What is the minimum order quantity?

We don't have a minimum order requirement. 1 piece is available. However, the cost will be lower if the order quantity is bigger. Because once the mold is created and the machine is set up, additional parts can be manufactured very fast and at a very low cost.

How long does it take for reorders?

Your mold will be preserved forever. If you need to reorder, place the order, prepare the materials, manufacture, delivery. Molds making and debugging time will be saved.

May I know some examples of overmolded?

The soft rubber grip of toothbrush, the handle of screwdriver, and Paring knife handle, etc.

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