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HomeTips & GuidesCable Overmolding: The Ultimate Guide on Overmolded Cable Assemblies

Cable Overmolding: The Ultimate Guide on Overmolded Cable Assemblies

If you plan on exposing your cable assembly to high-pressure washdowns, frequent flex and strain, debris or dust, and extreme weather, you should turn to cable overmolding.  

Why? Let’s find out the reason.          

Table of Contents


What is Cable Overmolding?

Cable overmolding involves loading unprotected bare cable assemblies into a precision-crafted mold set tool and filling the cavity with your desired molding material

Therefore, effectively surrounding your component in your desired shape creates a protected and sealed product you can handle and test.

Mold Set Tool

Dies or molds are the tools you use to manufacture the molded part. Generally, molds aren’t cheap to make and the more special the design, the higher the cost of production.

Tooling Material

Depending on how many cycles you expose it to, you can use different materials to make molds. 

  • Hardened Steel: these cost the most to manufacture because of their long lifespan and ability to endure countless cycles before they start to wear out. Often, hardened steel molds are used in mass-production environments.
  • Aluminum: these cost significantly less to manufacture than hardened steel molds due to their shorter lifespan. Often, these molds are used in prototypes to prove a design or projects that aren’t exposed to countless cycles.
  • 3D-printed materials: Also, for smaller quantities, you can create molds from 3D-printed materials for testing or to make smaller cable runs. 3D molds are much cheaper and easier to install. However, you can only use them for up to 100 cables.

Tooling Design

You can design your mold as a multiple or single cavity. With multiple cavity molds, each cavity is identical in design, enabling you to create numerous molds in a single cycle. 

Although not all the cavities are identical, such designs bring forth major problems, including ensuring the resin flows into the non-identical cavities without creating air gaps or voids.

Molding material

Your material of choice should be according to the tooling material. If your resin is thermoplastic, you can either use aluminum or steel. 

However, opting for steel is best if you plan the material to be a liquid injection type. 

If you want a liquid injection, you must use precise measurements for the tooling to avoid gaps or specs that could allow the liquid to escape rapidly.

Molding process

Overmolding is possible by forcing molding material into the mold cavity under intense pressure. 

The injection molding machine, commonly called a press, has a storage space for the resin. Often, the space is referred to as the hopper. 

Delivery for the material is normally a screw-type plunger or injection ram enclosed in a metal tube (barrel). 

Heating elements are incorporated in the machine’s barrel that heats the resin to a molten state. 

  • As molding occurs, the resin material mixed with colorants is delivered into a heated barrel via a hopper. 
  • The mixed resin moves toward your molding tool through the material heating and pressure of the screws. 
  • The melted resin gathers at the barrel’s end, at which point it’s referred to as a shot. A shot is the amount of resin required to fill your cavities and allows for some extra if the resin shrinks, which is expected. Generally, it only takes a few minutes for a cavity to fill.
  • The ram or injection screw keeps pressing the shot until the resin at the cavity’s gate cools and solidifies. The cavity’s gate is the narrowest part of your molding tool, so it solidifies first.  The mixture cools once in the cavity, using mold design features, such as part numbers, logos, or trade names. 
  • To help the cooling process, you can circulate oil or water through your molding tool in a series of channels and openings. Once the resin cools until solid, you can open the mold to reveal the final product. To assist you in removing the mold, you can use metal fingers or pins.
  • Once you remove the cycle, you can begin the cycle again. Once the material is solid, your molding machine cycles, preparing the next shot for another cycle. 
Bare wires with connector attached 

Bare wires with connector attached 

Benefits of Cable Overmolding

This key design feature integrates a connector to the cable, thus offering several benefits. 

Increase Protection

  • The mold configurations and materials used are immensely controlled during molding, which helps create a bond around the cables and connectors. The bond creates a watertight seal around vital cable assemblies. Furthermore, a properly molded connector will likely pass strict industry standards.
  • Overmolding fills the gaps around internal components, preventing any components from moving around, thus improving performance.
  • Overmolding creates a robust barrier around the components, protecting them from physical damage, especially for applications where human handling is crucial.

High-Compressed Assembly and Integration

Overmolding generally produces a smaller assembly than other assembly options, like mechanical backshells. 

The small design allows manufacturers to reduce the size of their equipment or products.


Thanks to various mold configurations, you can create a cable tailored to your equipment’s environmental concerns.

Improperly handling a cable often fails the electrical components. 

You can improve an overmold assembly’s lifespan by incorporating relief geometries, such as splitting 900 and 450 or straight.

Fewer Installation Errors

Because you don’t need further assembly, installation is quick and simple, helping minimize any chances of human error.

Overmolded cable assemblies 

Overmolded cable assemblies 

Custom Molded Cables at Cloom

At Cloom, we provide limitless overmolding capabilities, such as;

  • Custom dies: right angle, straight, or customer-specific designs for various connectivity solutions.
  • Custom resins: TPR, PVC, TPU, polyurethane, nylon, polypropylene and PVC thermoplastic rubber.
  • Custom names and logos: you can include a logo to create a permanent name for your product or labels to facilitate installation and maintenance.
  • Custom colors.
  • Custom molds: for circular connectors or military-specified connectors.
  • Exit point angle alignment.
  • Customer support using 3D modeling to help reduce costs and save time.
  • Inclusion of attachment hardware.
  • Maintain a big library of standard overmolding tools that you can apply as you want.


When overmolding your cable assemblies, choose the material that better serves your application. For all your cable overmolding needs, feel free to contact Cloom Tech.

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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