Bend Radius

What is Bend Radius?

The bending radius refers to the smallest radius at which a cable can be bent without damage. This radius corresponds to the centerline of the cable, which is the neutral fiber.As the radius decreases, the cable material must become more durable. An analogy can be drawn with human activity: if I want to curl up tighter, my spine needs to be more flexible; once the limit is exceeded, pain will result, which may even lead to spinal damage. Similarly, a cable can break if it is bent too far.

The minimum bending radius refers to the radius below which an optical fiber cannot be bent. The radius of the carrier should be selected based on the maximum value of the cable diameter. It is important to ensure that the correct carrier radius is taken into account in the calculations. Ideally, the largest possible radius should be used, as going below this radius may result in accelerated failures. 

Why is The Bend Radius of Fiber Optic Cables Important?

Protecting The Integrity of the Fiber

The fiber optic core is the most central part of a fiber optic cable and is usually only about 125 microns in diameter. If the bend radius is too small, the fiber core is subjected to high stress and deformation, which may cause the fiber to break or affect its optical performance.

Avoiding Signal Transmission Losses of Optical Fiber

When fiber optic cables are bent, bending loss occurs, resulting in a decrease in the power of the optical signal. If the bending radius is too small, this loss increases significantly, seriously affecting the quality of signal transmission.

Ensure Long-term Stability And Reliability

Excessive bending accelerates the aging of optical fibers and shortens the service life of fiber optic cables. Following the recommended bend radius helps maintain the reliability and long-term stability of fiber optic cables.

Compliance with International Standards

The bend radius of fiber optic cables is governed by international standards and codes. Compliance with these standards helps ensure the safety and compatibility of fiber optic cables.

Principles and Recommendations for Selecting a Bend Radius

It is important to follow the minimum radius recommended by the manufacturer, but it is optimal to use as large a radius as possible. The basic principle is that cables should be bent in such a way as to avoid sharp bends and to ensure that the connection points are not subjected to mechanical stress. If the cable is installed through a loop, the bending radius should be at least 10 times the cable diameter. The larger the radius, the less stress the cable will be subjected to, thus extending its service life. It should be noted that the minimum bending radius depends in part on the temperature range at the time of bending. Particular care needs to be taken when the ambient temperature approaches or exceeds that temperature for the cable.

This is especially important at low temperatures where thermoplastic cables tend to stiffen. Rigid cables may increase the radius of the carrier and cause mechanical problems. It is therefore recommended to use cables with PUR or TPE jackets at low temperatures and to consult the manufacturer for advice on bending radius. In space-constrained applications where cable carriers smaller than the recommended minimum bend radius must be used, it is advisable to use cables specifically designed for low bend radius.

Application Scenarios for Cables with a Tight Bend Radius

Cables with a tight bend radius are in demand in a wide range of applications, especially where flexible and dynamic movements are required in confined spaces. For example, they are commonly used in the semiconductor and assembly industry, the automation industry as well as the automotive and banking industries. Increasingly, new applications are also beginning to appear in automated doors in cars and trains, in vending machines and in the packaging industry.