What are bend radius and minimum bend radius?

The bend radius is the radius with which a cable can be bent without damaging it (including kinking). The smaller the radius, the greater the required flexibility of the material. A frequently asked question in this context is: How much can we bend a cable without damaging it or impairing its function? The answer depends mainly on the particular cable being considered. There are several industry standards such as IEEE 1185, ICEA S-75-381, ICEA S-66-524 or ICEA S-68-516 that specify minimum bend radius for many different cable types.

Take the minimum bend radius into account when selecting cables and cable trays

The minimum bend radius is the radius below which an object must not be bent. Cable trays are used in many installations, so the question arises: How do you select the bend radius of a cable or cable tray?

When specifying a cable management system, there are various options for extending the service life of cables. One of the most important factors is choosing the right bend radius for the cable tray. It is important that the radius is larger than the recommended minimum bend radius of the cables (with the possible exception of applications with space restrictions). One of the most important factors for longevity and operational safety is choosing the right radius for the cable tray. All cable trays have several bend radii to choose from and each manufacturer suggests a minimum bend radius. The radius selected for the cable tray depends on the cable with the largest diameter.

General rules and recommendations for selecting the radius

Do not exceed the minimum radius recommended by the manufacturer - however, the largest possible radius is optimal. As a general rule, cables with flexible specifications that move must be supported in such a way that the connection points are not mechanically stressed and sharp bending is avoided. If this is achieved with a loop, the cable must be provided with a bend radius of at least 10 times the diameter of the cable. The larger the radius, the less load is exerted on the cable, which ensures a longer service life. It should be noted that the minimum bend radius is partly based on a temperature range for bending. Special care is required if the ambient temperature reaches or exceeds this temperature for the cable.

This applies in particular to low-temperature applications where thermoplastic cables are used, which tend to stiffen when exposed to cold. Stiff cables can increase the radius of the cable support and lead to mechanical faults. It is recommended to use a cable with a PUR or TPE jacket at low temperature and/or consult the manufacturer for bend radius recommendations. In applications with severe space constraints, the radius of the cable support may need to be smaller than the recommended minimum bend radius for the infill package. This is not ideal, but if it cannot be avoided, cables specifically designed for low bend radius installations should be used. The igus® chainflex® range includes resilient control cables, servo and motor cables or robot cables as well as encoder cables, bus cables and data cables, which can be used safely in demanding environments and are characterised by their particularly long service life.

bend radius for cables under 4xd
In the past, users of very small energy chains and the usually very tight bend radius associated with them have been faced with the question of suitable cables for often very high stroke rates. Copper quickly reaches its physical limits with a bend radius of less than 5xd, making it necessary to search for suitable replacement conductor materials or fundamentally different conductor structures. Alloys are used here. Although these have excellent mechanical specifications, they have reduced conductivity compared to copper. The conductor diameter of the alloyed conductor is therefore slightly larger.