What is over-mold in cable assembly?

POTTING AND MOLDING ELECTRICAL CABLE ASSEMBLY TERMINATIONS

molding: a process for creating a physical form to protect a cable termination from hazards in the operating environment, as well as to provide strain relief.

potting: a process for creating a physical form to protect a cable connector from hazards in the operating environment, to help insulate bare wire terminations in the connector from each another.

Overmolding in cable assembly is a manufacturing process where a plastic material is injected under pressure into a mold, encapsulating a pre-assembled cable and connector to create a single, unified part. It's like adding a protective and functional outer shell to the cable assembly.

Here's a breakdown of the process:

Preparation: The cable and connector are assembled and positioned within the mold cavity.
Injection: Molten plastic is injected into the mold under high pressure, filling all the gaps and cavities around the cable and connector.
Cooling: The mold is cooled, allowing the plastic to solidify and form the final overmolded part.
Finishing: The overmolded cable assembly is trimmed and inspected to ensure quality and functionality.

Overmolding can be mainly categorized into two processes:

(i) multi-material molding and

(ii) insert molding. Multi-material injection involves the injection of the first material, substrate, into the mold, and then the subsequent material is injected onto the solidified substrate

[3]. On the other hand, insert overmolding requires a previously prepared insert placed into the mold cavity, and then polymeric material that can be called overmolded material is injected directly on it

[4]. Thus, both variants of the overmolding processes promote the cost, process cycle and multifunctionally of the parts by eliminating the assembly without adapting any fastener, flexibility addition to the rigid parts, and lowering the process times via automated manufacturing implementations.

Overmolding offers several advantages over traditional cable assemblies:

Enhanced durability: The overmolding material protects the cable and connector from physical damage, abrasion, and chemicals. This makes them ideal for harsh environments.
Improved strain relief: The overmolding provides strain relief at the point where the cable meets the connector, preventing stress and wear on the connection.
Environmental sealing: The overmolding can create a watertight seal, protecting the internal components from moisture and contaminants.
Tamper resistance: The overmolding can encapsulate the connection, making it difficult to tamper with the assembly.
Customizable aesthetics: The overmolding process allows for the addition of logos, text, or other features to enhance the appearance of the cable assembly.

Overall, overmolding is a versatile and effective way to improve the performance and reliability of cable assemblies. It's commonly used in various industries, including automotive, medical, aerospace, and industrial automation.

Here are some additional things to keep in mind about overmolding:

The choice of overmolding material is important and depends on the specific application requirements. Common materials include TPU, nylon, and PVC.
The design of the mold is crucial for ensuring proper flow of the plastic and optimal part quality.
Overmolding can add cost and complexity to the manufacturing process.

Overmolded cable assemblies reduce or eliminate many of the risks and disadvantages associated with mechanically assembled cables. In most circumstances, over molding employs a two-step process. The two-step process includes the first step of applying an inner mold which is followed by application of the final overmold. The inner mold is used to encapsulate the terminations and the wires. In most circumstances, omitting the inner mold can allow wires to “float” to the surface during the molding process, resulting in cosmetic defects. The inner mold step precludes this issue because once the inner mold has been accomplished, the wires are securely held. Even if wires have come to the surface of the inner mold, this is not a problem since the wires may no longer move and applying the over mold fully covers the inner mold. Employing an inner mold also allows the use of multiple materials.

Overmolding technology is widely used in the injection molding process of thermoplastic polymers and employs in the assembly of two dissimilar thermoplastic polymers reinforcing fibers and fabrics. Also, thermoset composite systems can be used as a substrate in insert molding and combine with thermoplastic polymers to attain thermoset-thermoplastic hybrid composite structures. Hence, the achievement of overmolding process with cost-effective manufacturing solutions and short cycle times to manufacture multi-functional parts highly relies on the performance of bonding of dissimilar materials, and prevention of interdiffusion between insert and overmolded materials.

Source : https://www.sciencedirect.com/science/article/abs/pii/S1359835X21002475