Does the factor also apply to air or coolant hoses?

Hoses have their own minimum bend radius, often stricter than cables because they are pressurised. Take the value from the hose datasheet and compare; the strictest governs the chain.

May I go below the minimum radius once, during installation?

For static installation a smaller factor applies (usually 7.5×), but kinking is never allowed. A single kink leaves a permanent weak spot that later fails exactly there.

What if the machine has no room for the required radius?

Then choose cables with a lower factor: purpose-built flexible cables reach 6 to 7.5×. That is nearly always cheaper than rebuilding the machine.

What minimum bend radius does my cable need?

Figure: Bend radius R measured to the cable's neutral axis, not to the inside of the chain.

Why is the radius so decisive?

Every bend stretches the outer conductors and compresses the inner ones. The smaller the radius, the greater that strain per stroke. Below the minimum radius, hairline cracks form in the sheath and individual strands eventually break — usually right at the transition to the end connector.

Which factor applies to which cable?

Manufacturers state the factor in the datasheet; it depends on construction and sheath material. Flexible cables with PUR sheath and fine-stranded bundled conductors manage 7.5 to 10×. Cables with foil shields, coaxial construction or glass fibre require 12.5 to 20×. Without data, always assume a safe 15×.

What happens with too small a radius?

In practice we see three phases: first a corkscrew effect where the cable twists around its axis, then a visibly thicker spot where conductors migrate, and finally conductor breakage. On bus and encoder cables you notice it first as unexplained communication errors, long before the sheath shows anything.

Is a larger radius always better?

Technically yes for the cable, practically not always: each radius step costs build height and chain length, hence money and space. So choose the smallest radius with at least 20% margin above the cable requirement. That stays safe without making the machine taller.

Table — Minimum bend radius per cable type and diameter

Cable type	Factor	Ø 10 mm	Ø 16 mm
Flexibele kabel PUR, bewegend	10×	100 mm	160 mm
Flexibele kabel, vaste installatie	7,5×	75 mm	120 mm
Busleiding met folieschermen	12,5×	125 mm	200 mm
Lichtgeleider (LWL)	15×	150 mm	240 mm
Hydraulische slang	volgens fabrikant	≥ 150 mm	≥ 240 mm

Frequently asked questions

Does the factor also apply to air or coolant hoses?: Hoses have their own minimum bend radius, often stricter than cables because they are pressurised. Take the value from the hose datasheet and compare; the strictest governs the chain.
May I go below the minimum radius once, during installation?: For static installation a smaller factor applies (usually 7.5×), but kinking is never allowed. A single kink leaves a permanent weak spot that later fails exactly there.
What if the machine has no room for the required radius?: Then choose cables with a lower factor: purpose-built flexible cables reach 6 to 7.5×. That is nearly always cheaper than rebuilding the machine.