Overmolding vs. Insert Molding: What’s the Best Choice?

Plastic part production presents several insert molding difference technique choices. They are two popular choices. Different approaches result in distinct final products since the injection methods rely on the design and features of the insert molding process.

Table of Contents

Through the comparison of overmolding and insert molding, this piece delves into their respective strengths and weaknesses as well as sector-specific utilization scenarios.

What is Overmolding?


It is a manufacturing procedure. A single product is made by molding that mixes two or more materials. A substrate, typically found in stiff plastic form, is put inside a mold during processing. Over the substrate involves molding a second material that is typically soft or more flexible before creating the final product with additional features or improved looks.

  • Two-shot overmolding: a type of overmolding. One process requires two separate injections by means of this specially designed injection molding machine. With this methodology, multi-material complex components can be created, like a toothbrush handle with an accommodating grasp versus a plastic handle with soft seals and a stiff center.
  • Pick-and-Place Overmolding: With another approach, the pick-and-place process overmolding is possible. Pre-molded inserts are inserted into a mold cavity through manual or automated means during this process. Integration takes a two-step manufacturing process in place by combining two substances within one finished product.

What is Insert Molding?

Insert Molding

By putting a pre-shaped metal or molten plastic insert inside an insertion molding cavity, and then filling up the space by injecting surrounding plastic. With the insert, the already molten plastic and material form a robust bond, providing security. Through metal molten plastic insert addition, the strength or function of a component can be improved.

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

Injection molding is classified into three types: insert molding, overmolding, and molding with extra material added. Whereas inserts go inside double-injection molding before plaster material introduction, overmolding adds excess materials outside double-shot molding of the base component. How this difference impacts the strength, design flexibility, and functionality of injection molded metal parts used in the final output varies.

Overmolding vs. Insert Molding

It is possible to make soft or flexible grips using insert molding and overmolding, as well as improved ergonomics and improved aesthetics. Additionally, injection molding is unable to match the level of shock absorption and vibration dampening offered by machining. With the goal of improving part performance through metal-inserted design, insert molding and overmolding is the way to go. Connectors, sensors, and terminals are examples of components. It is used in both the electronics and automobile industries.

Overmolding & Insert Molding Industry Applications

Due to overmolding and insert molding, each method has a specific use in a variety of sectors. Possibilities exist for designers and engineers to improve product functionality, appearance, and longevity through these methods.


Both overmolding of plastic pellets and metal insert molding play key roles in tool, handle, grip, and component manufacturing for the industry. Comfort and ergonomics advantages stem from overmolding; through insert molding, strength, and conductivity are boosted via a seamless combination of plastic, and metal elements.

handle grip

Medical & Healthcare

These moldings are required for medical equipment. Softness or improved hold can result from overmolding devices. By combining metal components or sensors during the multiple layers of materials in the manufacturing process, insert injection molding adds strength and durability to medical equipment.


Both insert molding and overmolding together, insert molding and overmolding have advantages that benefit the electronics industry. To improve case durability and aesthetics, overmolding is essential; meanwhile, insert molding guarantees dependable links via added components.

Consumer & Recreational

When producing handles, grips, and distinctive goods, insert molding rather than overmolding is frequently utilized in the consumer and entertainment industries. Instead, choose insert molding that is used to improve durability and performance in a variety of products, like power tools, athletic gear, and playthings.



Strategies for overmolding include direct overmolding, insert molded part molding variation, and overmolding with inserts. Interior and exterior component design benefits from overmolding in terms of ergonomics and aesthetics. By including metal components like connections, switches, and sensors, the insert molded part molding, on the other hand, provides an alternate method for enhancing component performance and dependability.

Designing for Overmolding and Insert Molding: Tips and Best Practices

With these injection molding methods, multiple components can be integrated into a single part, offering increased aesthetics, functionality, and endurance. Here are some tips hand tools, and best practices to consider when designing two-shot molding:

Overmolding and Insert Molding: Tips and Best Practices

Early Collaboration with Manufacturers

Early involvement of an injection molding manufacturer leads to more efficient and cost-effective production processes. Identify potential difficulties, their expertise strong, and reusable connections they can help you with. Ensuring consistency across various injection molded part manufacturers requires coordination, which also helps you stay within their capabilities and restrictions.

Material Selection

Compatibility with the process should be considered when choosing materials. A solid mechanical linkup needs to exist between the fundamental material and whatever else that will get injected. Find the optimal mix of materials with input from your manufacturing expert.

Component Geometry and Placement

thermoplastic composite overmolding

For Overmolding:

  • Made to be easily ejected from the overmolding process, the major component (base) should have sufficient draft angles.
  • Between the base and overmolded plastic materials, pay close attention to the interface. Process simplicity is hindered by design factors like undercuts.
  • To avoid part distortion when cooling, consider material shrinkage rates first.

For Insert Molding:

  • Attaching them to the insert injection molded parts part requires designing components with undercuts, knurls, or grooves.
  • Insert placement must be precise for correct positioning during the insert injection molding itself.
  • Spacing between inserts should be just right to avoid disruption during insertion.

Tolerances and Clearances

Components threaded inserts must have well-defined interface areas with tolerance and clearance parameters. Tight fittingness between the malleable material and either the foundation or between molten plastics of an insert guarantees a robust connection without any undesirable motion or space.

Surface Finish and Texture

Overmolding and Insert molding

The surface finish and texture for the base plus the complementary or contrasting color of the overmolded plastic material must be considered together. Clear communication with the manufacturer regarding the desired texture or look is crucial when engaging other manufacturing services in overmolding.

Gate Locations and Flow Analysis

Determine the most effective spots in collaboration with your production partner. Identify potential quality issues like air traps or insufficient material flows by analyzing the flow of materials, these tools allow.

Part Orientation

Consideration must be given to how your role fits into the bigger picture of the entire double injection molding process, so that you may simplify things. Better material flow results when the proper orientation of plastic parts is maintained complex two shot involves molding is up.

Prototyping and Testing

Prototype creation or small-scale testing before full-scale production complex two-shot mold, is key. Identifying and addressing any necessary adjustments enables optimization of the both processes.

Pros and Cons of Overmolding vs. Insert Molding

Two options for injection molding, both with pros and cons. Knowing the pros and cons of the two-step process makes it easier to decide on the ideal method that involves injection molding for your unique project. Let’s compare the above two processes:


Overmolding products


  1. Enhanced Aesthetics: With the overmolding process, products gain an appealing visual component and improved ergonomics through mixing various materials, colors, and textures within a single component.
  2. Improved Sealing: Resistance to moisture, dust, and other substances results from overmolding. Harsh environments provide value to this.
  3. Reduced Assembly: Reducing the need for additional assembly steps through the overmolding process leads to cost savings and faster production.
  4. Design Flexibility: Design flexibility allows overmolding to create one-of-a-kind and sophisticated part shapes and details.
  5. Reduced Material Waste: Efficiency is key when it comes to overmolding, thanks to the injection molding process which minimizes waste by maximizing materials.

Few cons follow when it comes to overmolding.

  1. Complex Tooling: Standard injection molding may have higher initial setup costs than tooling that is more complex and costly.
  2. Longer Cycle Times: With longer cooling times and multi-material processes involved in injection molded parts, the cycle time. efficiency in production could suffer as a result.
  3. Limited Material Compatibility: Material compatibility is crucial for successful overmolding processes.

Insert Molding

Insert Molding products


Insert molding has numerous positive and useful properties including:

  1. Strength and Durability: Strong bonds between components and the plastic surroundings create parts exhibiting great mechanical qualities.
  2. Cost Efficiency: By cutting down on waste disposal fees and streamlining manufacturing processes, high production rates become more affordable.
  3. Design Precision: With precision control over insert positioning, this approach works well for components boasting particular functionality or built-in attributes.
  4. Versatile Material Compatibility: Plastic, metal, and electronic components are some examples of items used in molding through insertion.

Despite offering advantages, the use of insert molding carries unexpected repercussions. It includes:

  1. Assembly Complexity: Planning and tooling modification must be exact to guarantee correct insert positioning and adhesion through the design process.
  2. Limited Aesthetic Options: When it comes to colors and textures, overmolding offers more aesthetic flexibility than it does.
  3. Higher Initial Tooling Costs: Standard injection molding has higher initial tooling costs compared to while being cost-effective for high-volume production.
  4. Material Compatibility: Compatibility between the insert material and the surrounding plastic is crucial to prevent future bonding issues.


In conclusion, Overmolding and insert molding have significant value because they help in industrial production methods. With multiple manufacturing technologies, each offering distinct pros and uses, companies can fabricate practical and visually appealing, plastic and metal parts and components. Two manufacturing approaches provide cutting-edge solutions—overmolding and insert molding.

Why go to Hongju for your  Manufacturing needs?

Feel free to contact Hongju immediately. We look forward to engaging in collaborative discussions about how our state-of-the-art processes and tools can be the catalysts for your business growth and success. Rest assured, our dedicated team will be there for you every step of the way, fully committed to turning your visionary ideas into tangible realities.

untitled design (2)

Send Your Inquiry Now!

Quality Meets Affordability. Inquire Now for High-Quality Products at Low Volumes.

Get Instant Quote Now!

Share The Post Now:


Hey there, I’m David!

I’m the founder of Hongju Silicone. I have been in this field for more than two decades. If you are looking for custom-made silicone rubber products, feel free to ask me any questions.

You may also find these topics interesting

viton rubber

Viton Rubber: The Definitive Guide

The rapidly evolving demands of the modern world mean materials must operate in harsher environments for longer. In the case of elastomers, even materials such as nitrile rubbers can fall short of expectations. This is where Viton rubber comes into play.

Read More »
4 types of silicone

4 Types of Silicone and Their Distinctions

Silicone rubber, an elastomeric material known for its exceptional properties, plays a pivotal role in various industries, from medical devices to automotive applications. Understanding the 4 types of silicone and their distinctions—ranging from liquid silicone rubber (LSR) to high-consistency rubber (HCR)—is crucial for selecting the right material for your needs.

Read More »
epdm rubber

EPDM Rubber: The Definitive Guide

EPDM, or Ethylene Propylene Diene Monomer rubber, is a versatile material known for its durability and weather-resistant properties. It is used in a wide range of industries, including roofing, automotive, and construction.

Read More »

Request for Quote

*All inquiries will be responded to within 24 hours.

Send Your Inquiry

*We respect your confidentiality and all information is protected.

Download Catalog

Fill in the form below, and we will send you our entire catalog immediately!