What are bend radius and minimum bend radius?

The bend radius is the radius by 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 carriers

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

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 carrier. 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 carrier. All cable carriers have several bend radii to choose from and each manufacturer suggests a minimum bend radius. The radius selected for the cable carrier 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 carrier 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 carrier 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 exceptionally long service life.

Bend radius for cables in the energy chain

Bend radii for cables under 4xd
In the past, users of very small energy chains and the usually very tight bend radii associated with them had to find suitable cables for often very high stroke rates. Copper quickly reaches its physical limits with a bend radius of less than 5xd, so that operators had to search for suitable replacement core materials or fundamentally different core structures. They often opt for alloys. Although these have excellent mechanical specifications, their conductivity is lower than that of copper. This means that the alloyed conductor's diameter is slightly larger.

Cables with a small bend radius
Dynamic applications with a tight bend radius quickly push the copper cores of conventional cables to their mechanical limits. Special igus cables offer increased operational reliability, particularly in areas of application that only have limited installation space but require a high number of strokes.

In addition to a stranded wire in a particularly bend-resistant design, extremely abrasion-resistant and highly bend-resistant jacket materials are used, which enable increased flexibility of the cable. With its many years of experience in its own test laboratory, igus can also guarantee a long service life and planning reliability in energy chains for chainflex cables with the smallest bend radii.

Where are cables with a tight bend radius used?

The areas of application for cables with a tight bend radius are diverse. They are very often required in applications where flexible and dynamic movements have to be carried out in the smallest of spaces. For example, they are used in the semiconductor and assembly industry, the automation sector as well as in the automotive and banking sectors. New applications are emerging in automatic doors for vehicles and trains as well as in automatic self-service food dispensing machines and the packaging industry.

Bend radii for cables under 4xd
In the past, users of very small energy chains and the usually very narrow 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.

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