Injection Molded Cable Assembly: Everything You Need To Know

Injection-molded cable assembly offers significant benefits over similar products with mechanical constructions. Although the molding process is complex, professional are still willing to put in the extra effort knowing they’ll get more appealing products that you can seal and is tamper-proof. For this reason, we will discuss the art of over-molding today.

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What Are Injection Molded Cable Assemblies?

Injection molded cable assembly, sometimes referred to as over-molding, is not only aesthetically appealing but also helps protect cables from extreme weather, intense pressure-wash-downs, constant strain and flex, and exposure to dirt or debris.  

It involves loading bare and unshielded cable assemblies into a mold set tool designed according to precise specifications. Then fill the cavity created with the right molding material, which effectively surrounds the component according to the set shape, resulting in a sealed and well-protected product. 

Mold Set Tool

Mold or dyes are the physical tools used to manufacture molded sections. Making molds is costly, and the more detailed it is, the higher the costs. 

Tooling Material 

You can use different metals to make molds based on the number of molding cycles you expose the metal to. For instance, if you use a  particular mold in a production setting to undergo hundreds of molding cycles, the metal of choice is most likely hardened steel. 

Hardened steel molds cost the most to produce. However, the upfront costs are eventually offset by the fact that it will last long before wearing out, even after undergoing countless molding cycles. In mass production, the metal of choice is often steel molds.

Aluminum is appropriate for molds that will experience a limited number of mold cycles or for those prototypes that can easily take on a particular mold design. Aluminum is a soft tooling material with a significantly shorter lifespan than its steel counterpart. However, its malleability means lower tool fabrication expenses. 

CNC (Computer Numeric Control) machines or electrical discharge machine processes produce most molds.

Computer Numeric Control Machine

Caption: Computer Numeric Control Machine

Tooling Material Choose

The substance used for molding determines the material you choose. The mold materials can be aluminum or hardened/stainless steel in cases where the resin is thermoplastic. The tooling must be hardened steel if the material is a liquid injection substance. To achieve liquid injection, you must produce the tooling component using precision measurements to eliminate any gaps or specs where the liquid could eject or splash through.

Using a small number of materials, you can make molds using 3D printed items that you can use to test the mold or to make smaller quantity cable runs. Using 3D-printed molds is also cost-effective, and you can complete the design quickly. However, it is usually capable of facilitating only 50 to 100 cables. 

Tooling Design

The design of a mold can either have a single or multiple-cavity setup. In the case of a multi-cavity mold, each cavity must be identical to produce several molds during a single mold cycle. In other situations, several cavity molds can encompass nonidentical cavities, leading to significant issues, such as ensuring that the resin can flow into the different cavities designed to ensure no air gaps or voids. 

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Over-mold process 

First, transport the resin material via the hopper into the heated barrel. The actual heating of the material and the forces exerted by the screw leads to the mixed and softened resin going toward the molding tool. The shot, which refers to the resin, must fill the mold cavities. It also has an allowance for any unexpected shrinkage experienced by the resin. The standard filling time for a cavity is seconds. 

The injection ram or screw continues to exert pressure on the shot/resin found in the machine’s entrance until it cools and hardens. This opening to the cavities is typically the smallest or narrowest section of the molding tool. As a result, it is the first area to solidify. When the material at the entrance hardens, the injection molding tool will start to cycle as it prepares another shot and waits for the upcoming molding cycle. The resin within the mold cavity will continue to cool, and you can extract it once it solidifies. 

To help with the cooling process, you can circulate oil or water through the mold apparatus via channels or openings. Once the resin cools to the point that it turns solid, the mold will open up, allowing you to remove the completed piece. Metal fingers or pins within the mold tool can aid in the removal. Once removed from the cavity, the cycle can start over again.

Molding Material

You can over-mold by pushing materials into a mold cavity with immense pressure. The most commonly used materials for cable assemblies are thermoset or thermoplastic materials. The injection molding or press machine has a storage area for the mold resin. In some cases, you can refer to it as a hopper. The delivery means for the material is typically through an injection ram or screw-type plunger found inside a metal tube, sometimes referred to as a barrel. Heating elements are also placed inside the barrel of the machine that heats the resin into a molten state. 

Benefits of Injection Molded Cable Assemblies

Below are the main benefits of injection molded cable assemblies.

Increase Protection

The materials and mold configurations for using the overmolding process are highly controlled, which can lead to a bond forming around the cables and connectors. These bonds also result in creating a watertight seal around important cable assemblies. If you wish to have additional protection for your electrical components, this process can assist you in achieving IP-67, 68, and 69K standards. In addition, properly molded connectors can easily pass strict industry requirements. 

Protection from Shock and Vibration

If you expose your project to a high shock or vibrating environment, it will be more likely to incur mechanical damage or failure. You must take preventive steps during the design phase. The overmolding process can help fill the gaps around internal components, preventing overmolded components from moving inside the assembly. 

Shield from Physical Abuse

Things like harsh weather repeated friction, and high temperatures significantly reduce the lifespan of a product. Over-molding helps create an ultra-rugged barrier around the electrical components to prevent such physical damage. Polyurethane is the material used for over-molded electrical connections. It has a high load capacity and is available in many harnesses. It is also used in various applications where human handling is essential. 

High-Compressed Assembly and Integration

The overmolding process typically produces smaller pieces than other assembly methods like mechanical back-shells. This small size allows equipment creators to easily scale the components’ scope. In addition, the process helps to protect various pieces like resistors, electrical switches, PC board games, and diodes, which results in better performance. 

Flex and Strain Relief

This essential feature helps integrate a cable into the connector. It also offers protection from damage. Any improper handling of the cable can lead to the failure of the electrical components. The different kinds of relief geometrics improve the longevity of an overmolded assembly. 


The different materials used in designing a molded custom cable assembly allow for producing a cable tailored to your equipment’s specific environmental issues.

Fewer Installation Errors

Since there’s no need for additional assembly, you can install a molded cable quickly using a simple process that helps minimize the chances of human error.

Custom Molded Cables at Cloom

The custom-molded cables at Cloom offer users virtually unlimited over-molding features, some of which include:

  1. Customized resins, including Nylon, PVC thermoplastic rubber, TPU, TPR, polypropylene, and polyurethane. 
  2. Customized dies of client-tailored, straight, and right-angle mold designs for different connectivity solutions.
  3. Customized colors
  4. Customized names or logos to help create a permanent brand.  
  5. Customized molds for military-specified and circular connectors, i.e., 38999
  6. Offers a customized collection of over-molding tools that can serve your needs better. 
  7. The inclusion of attachment hardware
  8. We provide support to customers with 3D modeling through the use of custom dyes. The process also helps to save both time and money. 
  9. Users are provided with an exit point angle alignment.


The whole process of overmold starts when the resin feeds into the molding apparatus’s heated barrel at the end of the hopper. From this stage, mix any required colorants and then move across the barred length to the actual mold. At this point, push the resin and colorant mixture into the mold cavities. After it is inside the mold cavity, the material will cool down and take on any features designed into the mold, including trade names, logos, or part numbers. 



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