Overmolded Cable Assemblies vs Heat Shrink

Selecting the right cable protection method can significantly impact the performance, reliability and lifespan of your electrical system. Two common options are heat shrink tubing and overmolded cable assemblies. While both provide insulation and strain relief, they serve different purposes. Understanding their strengths will help engineers, OEMs and purchasing teams choose the best solution for their application.

What’s the difference?

Heat shrink tubing is a polymer sleeve that contracts when heated. It creates a snug fit around wires, connectors or cable splices. It provides electrical insulation, basic environmental protection and helps organize wiring.

Overmolded cable assemblies offer a more robust solution. During manufacturing, a durable polyurethane resin is moulded directly over the cable and connector interface, creating a seamless protective housing. Because the overmold becomes part of the cable assembly, it delivers superior mechanical strength, strain relief and environmental sealing.

How do they protect against moisture and mechanical stress?

Water ingress is one of the biggest differences between these two options. Standard heat shrink tubing protects against dust and incidental moisture, while adhesive-lined versions improve sealing by bonding to the cable jacket. However, repeated movement or damage can create gaps over time.

Overmolded cable assemblies form a continuous protective barrier around the connector transition, eliminating many potential entry points for moisture. This makes them ideal for outdoor equipment, transportation systems, industrial machinery and other applications exposed to rain, humidity, washdowns or condensation.

Mechanical stress is another common cause of cable failure. Heat shrink provides limited strain relief by reinforcing the cable termination. However, it is not designed for heavy pulling, constant vibration or repeated flexing. Overmolded cable assemblies distribute mechanical loads across a larger section of the cable. This reduces stress on internal conductors and connector pins. It also significantly improves pull strength and durability in demanding environments.

What is their chemical resistance and service life?

Industrial applications often expose cables to oils, fuels, solvents and cleaning agents. Heat shrink tubing provides moderate chemical resistance, depending on the material, but prolonged exposure can lead to cracking or loss of flexibility.

Overmolded cable assemblies can be manufactured using polyurethane resins engineered to resist chemicals, UV exposure, abrasion, moisture and extreme temperatures. As a result, they are commonly used in industries such as oil and gas, mining, aerospace, medical equipment, industrial automation and food processing.

These protective properties also contribute to a longer service life. Heat shrink performs well in controlled environments with minimal stress, while overmolded assemblies are designed to withstand vibration, temperature fluctuations, outdoor exposure and repeated handling over many years.

What is their cost vs. long-term value?

Heat shrink tubing is generally the more economical option. It requires minimal material and simple installation, making it well suited for repairs, prototypes and low-risk applications. Heat shrink remains an excellent choice for simple electrical repairs, wire identification, cable organization and applications with limited environmental exposure.

Overmolded cable assemblies require specialized tooling and manufacturing, resulting in a higher initial investment. However, medium- and high-volume production often benefits from lower maintenance costs, fewer field failures, faster installation and improved long-term reliability. When evaluating costs, considering total cost of ownership rather than purchase price alone provides a more accurate comparison.

Overmolded cable assemblies are the preferred option when durability, reliability and environmental protection are essential. They help reduce downtime and extend product life in demanding operating conditions.

Contact Flux Connectivity today!

We manufacture custom Overmolded Cable Assemblies using our proprietary FluxForce® polyurethane resins. Our assemblies resist water ingress, oil, UV exposure, heat, flame and abrasion while operating in temperatures from -40°C to 90°C. They also simplify installation through colour-coded designs and provide exceptional strain relief to protect cables in challenging environments.

To learn more, please don’t hesitate to give us a call at 1-800-557-FLUX or email us at connect@fluxconnectivity.com. You may also fill out the form on our Contact Us page!