Flexibility and Bend Radius Considerations for your Wiring Harness

To determine a wire or cable's bend radius, data sheets generally provide a multiplier that is used against the wire's outer diameter (OD). This multiplier indicates the smallest radius at which the cable can be bent without causing damage. Bend radius is influenced by factors like insulation material, construction (solid vs. stranded), wire gauge, and OD. More flexible materials, such as silicone and GXL, allow for tighter bends, while stiffer materials, like PVC, require larger bend radii.

Figure 1 illustrates how to calculate the bend radius based on the OD and multiplier from the data sheet.

Figure 1. How to determine a wire or cable’s bend radius

In general applications requiring tight bends, silicone wires are a versatile choice due to their flexibility and ability to handle small bend radii, typically 6-8 times the OD. For more intense applications involving frequent or continuous movement, such as drag chains or robotic arms, cables like Igus Chainflex and Belden Flex are specifically designed for durability and long-term performance without degradation, even in high-motion environments.

Table 1 below outlines common bend radius values for various wire types used by MiniProto.

If you can’t find the specific bend radius in a cable’s data sheet, a safe rule of thumb is to multiply the outer diameter (OD) by 12 to determine the minimum bend radius.

Type	Category	Bend Radius (~x OD)	Application
UL1007	wire	10-12	Static wiring, low movement, general-purpose use
Silicone	wire	6-8	Prototyping, tight bends, high-temp environments
Non-Flex Cable (ex. UL2464)	cable	10-12	Static cabling, minimal movement, general purpose
High-Flex Cable (ex. Igus Chainflex)	cable	4-8	Dynamic applications like cable carriers, robotics

Table 1. Wire types, bend radius and applications

Conclusion

When selecting a wire or cable, always ensure the bend radius aligns with your application’s requirements. Check your geometry and confirm that the cable can be bent within its specified limits to avoid damage or performance issues. If detailed specifications aren’t available, applying the rule of thumb (12 times the outer diameter) provides a safe guideline.

For further reading on bend radius, refer to the Keystone Cable guide and the Igus blog.