Selecting flexible cables requires careful consideration. Choosing a cable that fails to deliver adequate flexibility can lead to a host of problems. For example, stationary cables may be marketed as flexible, but they are not suitable for continuous flex operation. Excessive movement can cause the cable to corkscrew, leading to broken conductors, ruptured jackets and ultimate cable failure. The degree to which cables bend, twist and flex depends on their construction. This blog post, the second in our series on flexible cables, will describe some of the construction elements of various cable types and how they affect flexibility and reliability.

 

Start With the Conductor

To assess a cable’s flexibility, look inside at the conductors. High-strand-count conductors made from extra-fine tin or bare copper wires offer greater pliability to endure stress and withstand tighter bends without fatigue or breaking. Fine strands must be properly engineered to avoid kinking. Conversely, tray cables typically use conventionally stranded conductors that cannot support motion, even if they may bend during installation.

 

For continuous flexible cables, conductors with a short lay pitch length will maximize the cable’s lifetime under constant bending and mechanical stress. The most appropriate continuous flex cable stranding will be application-specific and determined by the cable manufacturer. At SAB, we draw our own copper strands to meet specific flexing criteria.

 

Another factor in cable flexibility? The conductor design. For continuous flexible cables, it is very important that the various layers in multi-strand cables are specifically adjusted to one another. For certain applications or very long travel distances, bundled conductors can be very advantageous. That is why it’s essential to understand the customer’s specific application.

 

Outside the cable, polyurethane (PUR) and PVC are often used for the jacketing thanks to their flexibility under high-speed repetitive motion, durability in industrial environments and resistance to oils and chemicals.

 

Make Sure Your Flexible Cable Is Built to Last

Because cable flexibility, reliability and lifetime depend on cable construction, it is critical to understand how your cable is built to ensure it will withstand its operating and environmental conditions. An ideal cable supplier can walk you through these and other construction elements to help identify the best cable for your industrial application. Part 3 of this series will explain how cable testing can help you predict your flexible cable’s viability and reliability when deployed in the field.

 

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