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WhatIs the Overmolding Process, and Why Is It Important?

Posted by Evan Freemon on April 05, 2019 | Updated on April 19, 2024

What is overmolding?

At iCONN Systems, we provide custom-designed and application-specific connectors and cable assemblies, and overmolding is no exception. Our overmolding capabilities allow you to create a cable assembly that has a long lifespan, can be plugged and unplugged frequently, and can withstand heavy use and abrasion. If you’re looking for specialized connectors that are also branded or color-coded, overmolding is a process that can benefit you.

Be sure to contact iCONN Systems today for more information on how we can help with your overmolding requests.

Table of Contents

What Is Cable Overmolding?

Simply put, cable overmolding is an injection molding process in which two or more materials are used to combine the wire and overmolded cable connector to create a single part. To do this, the cable assembly is placed inside a mold. The first material (the substrate) is covered by the other materials in this process. The overmolding process requires a rigid plastic component to be overlaid with a TPU layer or other overmold materials using either the insert molding (a single shot) or multiple-shot molding (two-shot) technique.

Overmolding or overmolded cables are full assemblies that combine the wire and connector into one single, seamless piece. To do this, the overmolded cable assembly is placed inside a mold. Next, a molten plastic material is injected into the mold cavity. Once the plastic material cools and solidifies, it conforms to the shape of the mold and encapsulates the junction point between the connector and wire.

What Are the Benefits of an Overmolded Cable?

Collectively, all the advantages of overmolding boil down to two things: greater lifespan and reliability. Overmolding shields internal components, fortifies protective qualities and helps overmolded cable assemblies survive in even the most rugged environments. By overmolding your cable assemblies, you will:

  • Increase the flexibility at the cable exit, where most of the movement between a cable and connector takes place
  • Provide resistance to abrasion and shock or impact
  • Make cable assemblies tamper-proof by encapsulating components beneath a sealed resin
  • Provide 360-degree strain relief and increased pull strength
  • Create a water-resistant or water-tight seal that qualifies cable assemblies for IP certification
  • Improve the overall quality, appearance and feel of cable assemblies, replacing the need for expensive metal backshells
  • Simplify installation by creating a one-piece assembly with keys that act as visual indicators to assist in the mating of each pair
  • Reduce human error

Overmolding Guide

In the most basic sense, overmolding is a performance enhancer for products and electrical components. The process of overmolding involves bonding a layer of durable material over an already existing part to create a single unit—for example, the adjoining of a cable and a connector. The goal of overmolding is to create the best possible adhesion between the cable, connector and overmolding material.

Customizations to Your Overmolded Cable Assemblies

The less obvious advantage of overmolding your cable assemblies is the level of customization that can be applied. While it is possible to overmold existing assemblies, you can also create a unique product that perfectly meets the requirements of your application. Customizable components of your overmolded cable include:

  • The overmold color, which can be strategically chosen to color code assemblies, complement brand colors, match the cable jacket or blend in with equipment
  • The presence of a logo or company name on the overmolding
  • The presence of flanges, which can be used at attachment points
  • The design, which is available in straight, right-angle or any other exit required to meet the needs of your application
  • LED indicator lights, which decrease repair times by making bad connectors easy to locate
  • The material used, such as thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), Santoprene (TPV), or acrylonitrile butadiene styrene (ABS)

Common Applications

Cable overmolding is ideal for cable assemblies that will face extreme weather, high-pressure wash-downs, constant sanitation, frequent strain and flex, or exposure to dust or debris, as well as those that must be as aesthetically pleasing as they are reliable. The most common applications in which overmolding is used include solar energy, military equipment, consumer electronics, medical equipment and industrial/OEM applications.

Overmolding Material Selection

Thermal bonding is a mechanical interlock design that physically holds the overmolding material to the cable and connector. Thermal bonding can be achieved independently or in conjunction with other types of bonds. Below is a chart of the materials most commonly used and how they perform in the field.

The most important factor when making your selection is the compatibility between the cable jacket and the molding material.

Choosing the right material during the overmolding process is “make or break” for the success of your cable assembly and, ultimately, your product. The most important factor when making your selection is the compatibility between the cable jacket and the molding material. If materials aren’t correctly matched, then the best possible thermal bond won’t occur, which may result in over molding issues. The most common issues related to poor thermal bonding include separation between overmold material and cable.

Material Comparison Chart

Polyvinyl Chloride (PVC) Durable, excellent resistance to weather, flame, chemical, tension, and abrasion. Can be hard and rigid or soft and flexible. Poor regulatory reputation. Very stiff in cold weather.
Polypropylene (PP) Inexpensive and versatile. High impact and wear resistance. Flexible, with a high threshold for elongation. Resistant to acids and bases. Not ideal for UV exposure or high heat applications. Can become brittle in cold temperatures.
Acrylonitrile Butadiene Styrene (ABS) Tough. Impact and chemical resistant. Widely used across different industries. Low shrink. High dimensional stability. Affordable. Poor weather- and solvent-resistance. High smoke generation when burned.
Thermoplastic Polyurethane (TPU) High resistance to abrasion. High elasticity, great performer in low temperatures. Resistance to oil, grease, and solvents. Not as cost-effective as other materials.
Thermoplastic Rubber (TPR) Performs like rubber but processes like plastic. Slip resistant. Excellent weather resistance. High shock absorption and flexibility. Soft texture. Prone to warping.
Polybutylene terephthalate (PBT) Moderate to high strength. Can be tough and flexible. High resistance to fuels, oils, fats, and many solvents. Does not absorb flavors. Resistance to high temperatures. Not ideal for thin parts.

* Note: material properties may vary. This chart is for general reference purpose only.

Cable Overmolding Design Process

Design engineering for overmold tooling is a task of its own. Design considerations must be made for any overmolding project, as errors can have a major impact on production costs, cycle times, time-to-market and the overall quality and performance of the product — especially when designing multi-cavity molds and dealing with high volumes. Thanks to the growing sophistication and accessibility of prototyping technology, engineering teams can now 3D print a tool and test its functionality and manufacturability before production steel is cut. The ability to prototype significantly reduces cost, time and material waste.

The right manufacturer will have the capacity to provide the complete customization of overmolded cable assemblies, as well as high volume, quick turnaround production. 

When designing an overmolded cable, the key is to customize the design according to the exact specifications of the molding process. This is an extremely important step in development and should not be treated as an afterthought. Think of your molding design like it’s a house. The quality of the blueprint will determine how well a house structurally holds up and protects all the things that will dwell inside its walls.

The initial design of mold tooling for your cable assembly is no different. If the design isn’t compatible with the molding process and materials, it could result in deformities and other product issues that affect how the mold holds and shapes material. Overmolds can be designed to include synergistic features like mounting or hanging geometry.

Moldmaking starts using advanced computer software. This software allows designers to map out every detail of the mold and feed the data to a 3D printing machine for prototyping (more on this later). Molds can be designed to have single or multiple cavities to address either high- or low-volume production. The number of cavities will depend on your volume requirements with consideration for cost and cycle time.

Multi-Cavity Mold Designs vs. Single Cavity Mold Designs

Multi-cavity mold designs are best for high-volume production involving tens of thousands of parts per month or more. The cost will be greater up front, but the price per overmolded cable assembly part will be lower because they require less machine time to fulfill the order. A multi-cavity mold can have as few as two cavities or as many as 200 (depending on the part). For cable assemblies, the maximum number of cavities is generally eight.

Single cavity mold designs are best for low-volume production involving less than 5,000 pieces per month.

Technologies Used in the Overmolding Process

Tooling is the physical part or “mold” used to manufacture overmolded products. Tooling can be expensive to design and create, but advanced technologies are helping to lower the cost. The more intricate the design, the more costly the tooling. To help control costs, manufacturers also offer different metals and materials that can be used to build tooling. Which technologies and materials you choose will depend on the volume of product and the details of the design.

Aluminum Tooling

  • Best for low-volume production
  • Supports production quantities of 10,000 parts or more
  • Ideal for simpler mold designs to decrease manufacturing time and costs
  • Supports single and multi-cavity tooling designs
  • Offers better heat dissipation and eliminates the need for cooling lines
  • Relatively inexpensive

Steel Tooling

  • Best for high-volume production
  • Ideal for multi-cavity tooling designs
  • As quantities increase, part costs decrease
  • Able to support intricate designs
  • Offers more finishing options than other tooling materials

3D Printed Tooling (Rapid Prototyping)

  • Used to test tooling designs before mass production/final tooling
  • Tooling can also be created for small quantity production runs
  • The most cost-effective way to manufacture tooling
  • Fast turnaround time for finished tool
  • Can only survive the production of 50 to 100 mold cycles
  • Can make functional prototypes
  • Specific part complexities may limit the application of this option

MoldFlow Software

A specialized software used by engineers to create a simulation of how tooling designs will function. New part designs can immediately be analyzed to identify potential flaws that might otherwise not be discovered until the part is in production. The software helps detect existing and potential quality issues, like weld lines, deep undercuts, flow lines or inadequate draft angles. It can also predict molding machine requirements, which tremendously helps with cost estimation (larger machines cost more to operate).

Overmolding Prototypes

As you can see, the process of designing overmold tooling is a project all on its own! Design errors can have a dramatic impact on production costs, cycle times, time-to-market and the overall quality and performance of the cable overmolding — especially when designing multi-cavity molds and dealing with high volumes.

Thanks to the growing sophistication and accessibility of prototyping technology, engineering teams can now 3D print a tool and test its functionality and manufacturability before production steel is cut. The ability to prototype significantly reduces cost, time and material waste. 

Prototyping for Multi-Cavity Molds

Overmold prototyping is most valuable when designing for multi-cavity tooling. Creating a multi-cavity mold isn’t as simple as copying a CAD file multiple times. There are complex physics surrounding the thermal variations in a multi-cavity mold and how molten material flows through a mold’s gates, runners and sprues. The more complex the mold, the more complex the physics.

For this reason, it is imperative key adjustments be made – for example, adjusting the mold gate (including knock-outs) or using side actions. Using 3D printing, multi-cavity molds can be produced and tested fast and risk-free. Once the design and performance are approved, that cavity can be replicated using a stronger material to support high production volumes.

Overmolding, Injection Molding, and Insert Molding: What’s the Difference?

Injection Molding

Injection molding involves shooting molten plastic into a mold to create a solid piece. It is extremely versatile and used in a broad spectrum of applications and industries.

The Process: Injection molding is a term used interchangeably with “overmolding”. Both terms represent the process of heating thermoplastic material and using high pressure to force the material through a nozzle and into a mold. Once the mold is full, pressure (usually hydraulic) is applied to keep the materials tightly in place. As the materials cool, adhesion takes place. Once complete, the mold opens up, and the product drops out.

Insert Molding

Insert molding is the act of permanently adhering two parts together. It’s commonly used when placing threaded “inserts” into molded parts or encasing electrical connections.

The Process: This process will produce one part that is specifically manufactured to fit inside a larger injection molding design. Like injection molding, insert molding involves a thermoplastic material being forced into a molding cavity. But this time, the material fills in around the insert. The finished product is a single part comprised of both the insert and overmolding material.

Two-Shot Molding and Multi-Shot Molding

Two-shot or multi-shot molding is cost-efficient for large production volume (more than 10,000 parts). This process is ideal for parts made of multiple colors, materials or components.

The Process: Two-shot molding is similar to injection molding but requires a specific molding machine equipped with two or more nozzles. As the name suggests, this process involves injecting a single mold with multiple materials during a single molding cycle. After the first material is injected, a steel part creates space for the next material to be injected.

Ultimately, customizing your overmolded cable assembly is about reducing part costs and enhancing the performance of your product. This is the goal whether you’re making 2,000 parts or 2 million. When looking for a cable assembly manufacturer, find a partner who understands this goal and offers the support your team needs to achieve it.

Common Overmolding Myths Debunked

iCONN Systems is a design engineering firm with the expertise and manufacturing capabilities to help your development team customize the optimal cable assembly for any type of application or overmolded cable connector. Overmolding your connector and cable assembly can easily resolve your performance issues pertaining to product sealing, tamper-proofing, strain relief, and much more. Sometimes, however, there are false beliefs causing companies to rule out overmolding as an option on their products. iCONN Systems examines the top MYTHS about overmolding providing you with a clear view of how to decide if overmolding is right for you.

Overmolding Myths vs. Reality

Myth Reality
Response time is too long iCONN Systems can establish a program to ship product within 24 hours of order receipt.
Can only assure IP67 with a limited amount of resins and cables

iCONN Systems can provide IP67 with many materials.

Cost is too high

Through calculating a total cost to assemble, a molded product will be significantly less costly. You receive a 100% tested assembly. NO rework. NO scrap. PLUS your direct labor is used to increase the throughput of your core product.

Field installable has the same level of performance and quality as a molder product Molded product is tamper proof, and can provide additional sealing and strain relief. Also, the final product is more consistent through the use of an experienced connector assembly house.
Overmolded products lack flexibility

On the Contrary, field installable product is not flexible. Molded product can be developed in multiple shapes, sizes, and colors. Field installable products are set and may not be able to accommodate a variety of cable diameters, especially when a sealing grommet is used.

You must purchase a product that is already tooled iCONN Systems will develop, design and build a tool specifically for our customer's application.
Molded assemblies have larger MOQs iCONN Systems utilizes cell manufacturing processes and is able to provide low quantity requirements.

Interested in reading more about overmolded cable assemblies? These blogs are other great resources to check out:

Contact iCONN Systems Today for Custom Overmolded Cable Assemblies

iCONN Systems is a design engineering firm with the expertise and manufacturing capabilities to help your development team customize the optimal cable assembly for any type of application. We offer numerous advantages to ensure your customized overmolded cable assembly fits into the scope of your project, including a cellular manufacturing process that decreases cycle time, minimizes resource waste and results in a higher-quality product. We also add value to our services at every opportunity.

For example, offering rapid prototyping, verification and validation testing, and Advanced Product Quality Planning (APQP). From rugged outdoor environments that expose electrical connections to harsh weather elements to medical equipment that must be as aesthetically appealing as it is compliant and resistant to chemical cleaning or strain, iCONN will help make you successful in the market by eliminating concern regarding electrical failures in the field.

Contact our team today to get started!

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