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What are bend radius and minimum bend radius?

The bend radius is the radius at 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, which provide minimal bend radii for many different cable types.
 
When choosing cables and cable carriers, consider the minimum bend radius 

The minimum bend radius is the radius below which an object cannot be bent. In many installations, cable carriers are used, so the question arises: how do we select the bend radius of a cable or a cable carrier?


When deciding on a cable management system, there are several ways to extend the service life of the cable. One of the most important factors is the selection of the right bend radius for the cable carrier. It is important that the radius (except, perhaps, in space constrained applications) is greater than the recommended minimum bend radius of the cables. One of the key factors in long service life and operational reliability is choosing the right radius for the cable carrier. All cable carriers have several bend radii to choose from and each manufacturer proposes a minimum bend radius . The radius chosen for the cable carrier depends on the cable with the largest diameter.  
 

General rules and recommendations for selecting the radius

Do not exceed the manufacturer's recommended minimum radius - but the maximum radius is optimal. Basically, cables with flexible specifications that move must be supported so that the connection points are not mechanically stressed and a sharp bend is avoided. If this is achieved by 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 stress is exerted on the cables, which ensures a longer service life. It should be noted that the minimum bend radius is partially based on a temperature range for the bending. Particular care should be taken when the ambient temperature reaches or exceeds this temperature for the cable.
 
This is especially true for cryogenic applications where thermoplastic cables tend to stiffen when exposed to cold. Rigid cables can increase the radius of the cable carrier and lead to mechanical errors. It is recommended to use a cable with a PUR or TPE jacket at low temperature and/or to consult the manufacturer for recommendations on bend radii. For space constrained applications, the cable carrier radius must be less than the recommended minimum bend radius for the filling pack. This is not ideal, but if it cannot be avoided, cables designed specifically for low bend radius installations should be used. The igus chainflex range includes load-bearing control cables, servo and motor cables or robot cables as well as encoder cables, bus cables and data cables, which can be safely used in demanding environments and are characterised by their very long service life.

Bend radius for cables in the energy chain

Bend radii for cables under 4xdFor users of very small energy chains with mostly very narrow bend radii, the search for a suitable cable for very high stroke numbers has come up frequently in the past. At bend radii of less than 5xd, copper quickly reaches its physical limits, which necessitated the search for suitable substitute conductor materials or for fundamentally different conductor superstructures. Alloys are used here. Although they have excellent mechanical specifications, compared to copper have a reduced conductivity. The conductor diameter of the alloyed conductor is a little larger.

 

Cables with a small bend radius

Dynamic applications with tight bend radii can quickly allow the copper cores of conventional cables to meet their mechanical stress limits. Especially in areas of application that only have a small installation space but require a high number of strokes, special igus cables offer increased operational safety.

In addition to a stranded wire in a very bend-resistant design, very abrasion-resistant and highly resistant jacket materials are used, which increase the 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 tight bend radii are diverse. They are particularly needed in applications where flexible and dynamic movements must be carried out in the smallest possible installation space. For example, they are used in the semiconductor and assembly industry, the automation industry, as well as in the automotive and banking sectors. New application possibilities arise in automatic doors for vehicles and trains as well as in automatic self-service food vending machines and the packaging industry.

Cable in motion
Cable test graph
Bend radius for cables in the energy chain

Bend radii for cables under 4xd

For users of very small energy supply chains with mostly very narrow bend radii, the question for a suitable cable for very high stroke numbers has come up frequently in the past. At bend radii of less than 5xd, copper quickly reaches its physical limits, which necessitated the search for suitable substitute conductor materials or for fundamentally different conductor superstructures. Alloys are used here. Although they have excellent mechanical specifications, but compared to copper have a reduced conductivity. The conductor diameter of the alloyed conductor is thus a little larger.


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