Cable bend radius calculator

The tool multiplies the cable outside diameter by an application multiplier: 4× for fixed installation, 6× for occasional flexing, 8× for continuous flex, 10× for drag-chain/high-flex and 12× for robotic high-cycle duty. A 10 mm OD cable therefore needs 40, 60, 80, 100 or 120 mm respectively. These are typical engineering starting points — the manufacturer datasheet is authoritative for a specific cable.

For a fixed installation it is 4 × 10 = 40 mm; occasional flexing needs 60 mm, continuous flex 80 mm, drag-chain duty 100 mm and robotic/high-cycle 120 mm. The bend diameter is twice the radius, so the fixed-install cable needs 80 mm of clear space measured across the bend.

A tight bend strains the conductors beyond their elastic limit — the outside of the curve stretches and the inside compresses. For a cable that never moves that strain is harmless, but repeated flexing turns it into conductor fatigue and eventual fracture, so the multiplier grows with cycle count: 6× occasional, 8× continuous, 10× drag chain and 12× robotic. Stranding and construction vary the numbers, so check the datasheet.

A rule of thumb is to size the drag-chain inner height at cable OD plus clearance — typically 10–20% — so the cable can float without binding; a tighter 1.5×-of-OD upper bound prevents tangling in multi-cable runs. The tool returns the 1.5× sizing figure as a conservative estimate. The bend radius at the chain ends must also exceed the cable minimum for the flex cycle rating.

No — the bend diameter is exactly twice the bend radius, and datasheets almost always specify the radius. A radius of 40 mm means the cable centreline bends through a circle of 80 mm diameter, so if you are checking clearances, double the quoted radius before comparing it with the available space.