Cable OverMolding: Everything You Need To Know

About cable overmolding, Over-molding has significantly altered the performance of cable assemblies over the years, increasing the reliability and longevity of a cable assembly.

How does the process make it? 

Now learn more about cable overmolding from this comprehensive guide.

Benefits of Injection Molded Cable Assemblies

You can enjoy benefits by integrating a cable into a connector this way.

Increase Protection

The materials and mold configurations are rightly controlled, creating a bind around cables and connectors.

This waterproof seal around cable assemblies helps extend the protection level of electrical components.

Appropriately molded connectors help meet demanding industry standards.

Protection from Shock and Vibration

If you don’t take preventive actions early on, your product may malfunction when exposed to high vibration.

The over-molding process fills the space around internal components, stopping the over-molded components from sliding inside the unit.

Shield from Physical Abuse

Over-molding creates an incredibly tough barrier around electrical components to protect them from adverse weather and physical harm,  increasing service life and reducing the risk of cable failure.

High-Compressed Assembly and Integration

The over-molding process produces a smaller assembly than other methods. With this small size, equipment designers can reduce the size of their components.

This procedure also improves performance by protecting resistors, electric switches, and diodes.

Flex and Strain Relief

Electric components mostly fail due to improper cable management.

You can increase the lifespan of an over-molded assembly with relief geometries like straight, split 45-degree, and 90-degree.


The over-mold material, finish, color, and other physical materials can be customized, which helps in brand recognition and product identification.

Custom molded cable assemblies are stronger and more durable.

Fewer Installation Errors

Over-molding connectors provide top-notch results if you prioritize quality, reducing installation errors and improving performance.

Different types of overmolded cables

Different types of overmolded cables

The Process of Injection Molded Cable Assemblies

You mold a cable by applying intense pressure to a material in a mold cavity. 

The injection molding device comprises a mold resin storage area or a hopper.

Also, an injection ram housed in a barrel has heating components that heat the mold resin until it becomes molten.

You use the injection ram to feed the resin material into the heated barrel through the hopper during molding.

The combined and softened resin advances toward the mold tooling, thanks to the material’s actual heating and the forces of the screw. 

The point that the molten resin gathers at the end of the barrel is referred to as a shot. In most cases, a cavity fills in a matter of seconds.

Until the resin’s entry to the cavity cools and solidifies, the injection screw or ram exerts pressure on the shot.

Since the cavities’ entrances are the smallest and narrowest portions of the mold tooling, they are the first to solidify fully.

You can start the cycle by removing the molded part from the cavities.

The injection molding machine will then cycle through its operation, preparing another shot. 

You can combine the resin with any necessary colorants and press it into the mold cavities before transiting the length of the barrel to the mold.

As the material cools inside the mold cavity, the features built into the mold take on those characteristics, including logos, trade names, and part numbers.

Also, you can pump water or oil through the mold tooling’s openings to speed up the cooling process.

The mold will break open once the resin solidifies and cools to where it is supposed to be removed.

Pins or metal fingers can help with mold removal within the mold tooling. 

Overmolded charging cables

Overmolded charging cables

Mold Tool Understanding

A fundamental element in the injection molding process is the mold tool that creates a pathway for molten material to move from the barrel to the cavity.

The molds/dies can be costly, with more detailed molds costing more.  

Tooling Material 

Different metals are used to make molds, depending on how many molding cycles they will experience.

If a mold is going to go through many molding cycles, hardened steel is the best metal.

Hardened steel is the most expensive material to produce. It offers increased mold cycles and a longer lifespan before falling, making up for the initial costs.

Mass production settings often employ steel molds because of their strength.

You can use aluminum for prototype molds to validate a mold design. It also applies to molds that will only undergo a few mold cycles.

While aluminum has a shorter lifespan than steel, soft tooling is more malleable, which lowers the cost of making tools. 

Molds made from 3D-printed materials can be in smaller quantities to test the mold or make cable runs in small amounts.

Hard tooling is far more expensive and takes much longer to complete than using 3D-printed molds.

You can make most molds on CNC machines or using electrical discharge machining techniques.

In addition, the material chosen for the mold also depends on the material used for the molding.

If the resin is thermoplastic, you can use aluminum, hardened, or stainless steel as the mold material.

If you intend the liquid injection material, such as silicon, the tooling must be made of hardened steel, which helps remove specs or gaps where the liquid could escape as a flash.

In addition, you must manufacture the tooling to extremely precise measurements for the liquid injection to be successful. 

Tooling Design

You can create a mold with one or more cavities.

A multi-cavity mold enables the fabrication of several molds in a single mold cycle since each cavity is planned and manufactured to be identical.

Multiple cavity molds can occasionally have cavities that are not the same, though those designs pose serious problems, such as leaving gaps or voids.

You can avoid such issues by ensuring the resin flows entirely into the differently constructed cavities.

Ovemolded battery cables

Ovemolded battery cables

Molding Material/Resins Used In Molding

There are hundreds of different resins available on the market, each with specific features, benefits, and drawbacks.

For cable assemblies, thermoplastic or thermoset materials are the most popular materials used for an over-mold. 

Epoxy Resins

Epoxy resin provides the surface qualities of the mold as a gel coat, mass-casting resin, or laminating paste.

The advantages of epoxy resins include high strength, great adhesion, and low shrinkage during removal from the mold.

It’s a great option as a component of fiber-reinforced plastics used extensively in different Industries. 

Epoxy is a thermoset polymer that starts liquid but eventually solidifies through curing, often done in a mold.

Polyurethane Resins

Thermoplastic polyurethane resins have excellent tensile and tear strength while soft and elastic.

They are mostly used to create components that need rubber, such as elasticity.

Thermoplastic polyurethane is more expensive than other resins but makes it easier for objects that need to be grasped firmly in hand to grip.

The qualities of polyurethane casting resin vary depending on the application and purpose.

You can make elastomers, thermosets, and thermoplastics with it.

The two-component system of resin and hardener that makes up the resin hardens after mixing because of a chemical reaction.

Overmolded computer cables

Overmolded computer cables

Low-Pressure Molding vs. High-Pressure Injection Molding

Low-pressure molding replaced high-pressure injection molding due to its many benefits. 

High-pressure over-molding offers a wide choice of materials depending on the application environment.

You can over-mold assemblies without damaging the components using low-pressure over-molding.

Low-pressure moldingHigh-pressure injection molding
Low injection temperature (180-240)High injection temperature (230-300)
Low-infection offers a small selection of raw materials limited to thermoplastic polyamide.It uses a wide variety of plastic materials.
High waterproof sealing capability and good adhesionPrecision electrical components cannot be glued
Air pressure powers the glue injection machine, which does not pollute the environment.Hydraulic pressure powers the glue injection machine and is not harmful to the environment. 


Over-molding of cable assemblies has changed over the past few decades due to material and technological advancements.

They can withstand the rigors of the most demanding environments today. You can also use them in practically any industry and application. 

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