In Episode 14 of No Dumb Questions, we explain the crucial engineering difference between flexibility and flex life in custom cable design.
While the terms are often used interchangeably, they refer to two distinct mechanical properties. Flexibility dictates how easily a cable can be bent, routed, or manipulated. This property is primarily important for static installations, complex routing, or tight confined spaces where the cable only needs to be bent a limited number of times. Flexibility is typically achieved using high strand counts of fine-gauge wire paired with soft insulation materials, such as silicone rubber.
Flex life, on the other hand, measures how many dynamic bending or movement cycles a cable can withstand over its operational lifetime without suffering mechanical failure. This property is critical for automated applications—like robotics, continuous-flex C-track systems, and automated machinery—where a cable may be flexed millions of times.
A cable designed to be highly flexible does not automatically possess a high flex life. To achieve maximum flex life, engineers often utilize high-tensile copper alloys rather than standard soft copper to better resist repeated mechanical stress and prevent strand breakage over millions of cycles.
Key Technical Takeaways
- Flexibility: Refers to how easily a cable can bend. Essential for tight routing, ergonomics, and one-time static installations.
- Flex Life: Refers to durability under repeated motion. Measures the number of dynamic bend cycles a cable survives without failing.
- Flexible Materials: Achieved using very fine-stranded conductors and highly pliable insulating materials like silicone rubber.
- Flex Life Materials: Achieved using high-tensile materials, such as copper-based alloys, designed to withstand repetitive mechanical stress in automation and robotics.
- Design Tradeoffs: An ultra-flexible cable may not have a long flex life, so material selection must be tailored strictly to the application’s dynamic demands.
Next up! Episode 15: Why is temperature rating so important?
Episode 14 Transcript – Flex Life vs. Flexibility
Welcome to No Dumb Questions
Welcome back to another episode of No Dumb Questions, where the only dumb question is the question that isn’t asked. So we often hear about what’s the difference between flex life and flexibility. So if I only had some samples, maybe I can better demonstrate that. Oh, wait, just a sec…I have some samples right here.
What is Cable Flexibility?
So when we’re talking about flexibility, it’s really how flexible the cable is, and how it can be manipulated for maybe a one-time installation or whatever the case may be.
What is Cable Flex Life?
Flex life is how many times that cable can be flexed during the life of the cable. Good examples for that would be robotics, or C-track applications where they see a lot of repetitive movement. So in the C-track application, this cable might see millions of flex cycles and you want it to last a long time.
Oftentimes flexibility and the materials that are used to design for a flexible cable may also be the materials that we use for our cable of high flex life, but not necessarily. So there are some subtle differences.
Material Selection: Silicone Rubber vs. Copper Alloys
So some of the considerations: if you’re trying to design a cable that’s very flexible, you might want to go to a higher number of finer stranded (finer gauge size) stranded conductors and soft insulations like silicone rubber. That’s the example that I have here.
If you’re looking to do high flex life, you might want to consider copper-based alloys that have a higher tensile strength that can withstand multiple repeated flex cycles without breaking.
But as always, design consideration really has to focus based on the application and material selection. So if you have some questions, you can reach out to our technical engineering staff.
All right. Join us next time for another episode of No Dumb Questions. Thanks.