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Greenlogy TEC Engineering Tools · Wire Rope Greenlogy TEC · Wire Rope
Wire Rope Selector
Breaking Force, Safety Factor and Terminations
Enter the working load, the application and the termination. The selector recommends the construction and the smallest standard diameter using the GB/T 20118-2017 minimum breaking force factors, checks the assembled strength and gives the wire rope clip count.
Wire rope minimum breaking force table
Rope grade 1770 N/mm², values in kN; a dash means the construction is not made in that standard diameter.
| Construction | 6 | 8 | 10 | 12 | 14 | 16 | 20 | 24 | 28 | 32 | 36 | 40 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 6x7+FC FC | 21.0 | 37.4 | 58.4 | 84.1 | 114.5 | 149.5 | 233.6 | 336.4 | 457.9 | 598.1 | — | — |
| 6x19S+FC FC | 21.0 | 37.4 | 58.4 | 84.1 | 114.5 | 149.5 | 233.6 | 336.4 | 457.9 | 598.1 | 757.0 | 934.6 |
| 6x19S+IWR IWRC | 22.7 | 40.3 | 63.0 | 90.7 | 123.5 | 161.3 | 252.0 | 362.9 | 494.0 | 645.2 | 816.6 | 1008.2 |
| 6x36WS+FC FC | — | 37.2 | 58.1 | 83.6 | 113.8 | 148.6 | 232.2 | 334.4 | 455.2 | 594.5 | 752.4 | 928.9 |
| 6x36WS+IWR IWRC | — | 39.6 | 62.0 | 89.2 | 121.4 | 158.6 | 247.8 | 356.8 | 485.7 | 634.4 | 802.9 | 991.2 |
| 7x7 FC | 19.1 | 34.0 | 53.1 | 76.5 | 104.1 | 135.9 | — | — | — | — | — | — |
| 7x19 FC | 19.1 | 34.0 | 53.1 | 76.5 | 104.1 | 135.9 | 212.4 | — | — | — | — | — |
| 18x7+IWR IWRC | — | — | 53.1 | 76.5 | 104.1 | 135.9 | 212.4 | 305.9 | 416.3 | 543.7 | 688.2 | 849.6 |
| 19x7+IWR IWRC | — | — | 53.1 | 76.5 | 104.1 | 135.9 | 212.4 | 305.9 | 416.3 | 543.7 | 688.2 | 849.6 |
| 35x7+IWR IWRC | — | — | — | 72.6 | 98.9 | 129.1 | 201.8 | 290.6 | 395.5 | 516.6 | 653.8 | 807.1 |
Diameters in mm. The values are generated from each construction's minimum breaking force factor; the full table covers the 1570, 1670, 1770 and 1960 grades. Download CSV
Method and references
- Pick the application; the default safety factors are 5 for hoisting, 6 for slings and 4 for mooring, fishing and towing.
- Required MBF = load × safety factor ÷ termination efficiency; marine and high-temperature duty add 10%.
- Among the constructions ranked for the application, take the smallest standard diameter that reaches the required MBF.
- Check the assembled strength and the end: clip counts follow GB/T 5976-2006, spaced about 6 to 7 rope diameters apart.
Selection aid only. The final rope size must be verified by engineering calculation against the rope certificate, the governing design code and the termination test data.
References: GB/T 20118-2017 wire ropes, GB/T 5976-2006 wire rope clips, GB/T 3811-2008 crane design, ISO 2408.
Frequently asked questions
How is the minimum breaking force of a wire rope calculated?
The selector uses the coefficient method of GB/T 20118-2017: F_min = K x d x d x R0 / 1000, where K is the minimum breaking force factor of the construction and core, d is the nominal diameter in mm and R0 is the rope grade in N/mm2. The same factors generate the published tables, so the result follows the standard rather than a catalogue average.
Which safety factor should I use?
The page starts from common values: 5 for crane hoisting (GB/T 3811), 6 for lifting slings and rigging, and 4 for mooring, fishing gear and towing. Raise it for shock loads, personnel, abrasive or corrosive duty, and confirm the final value against the governing design code for your installation.
Does the rope end reduce the breaking force?
Yes. A termination is part of the load path, so the assembly is only as strong as the rope breaking force multiplied by the termination efficiency. The selector uses about 90% for a spliced thimble eye or a swaged ferrule, 85% for a hand-spliced eye, 80% for wire rope clips and 100% for a spelter or resin socket, and it sizes the rope so that the assembled strength still covers load x safety factor.
How many wire rope clips do I need?
Following the GB/T 5976-2006 recommendation, the page shows 3 clips up to 16 mm, 4 clips for 18-26 mm, 5 for 28-36 mm, 6 for 38-44 mm and 7 for 46-60 mm, spaced about 6 to 7 rope diameters apart with the last clip at least 140 mm from the rope end. Always follow the clip manufacturer's installation data.
Should I choose 6x19 or 6x36?
6x36WS has more wires and a longer lay, so it bends more easily and lasts longer over sheaves; it is the usual crane rope. 6x19S has fewer, thicker wires: it is stiffer and more abrasion resistant, which suits slings, mooring and worn or dirty duty.
What is the difference between FC and IWRC?
A fibre core (FC) is flexible and inexpensive but loses strength at high temperature and under crushing. An independent wire rope core (IWRC) raises the breaking force by about 8%, resists crushing and multi-layer spooling, and is preferred above 100 C or wherever the rope is bent hard.
Which standard is the data based on?
Construction factors follow GB/T 20118-2017 (Wire ropes - General purpose technical conditions) and its ISO 2408 equivalent; clip counts follow GB/T 5976-2006. The result is a selection aid: the final size must be verified by engineering calculation against the actual rope certificate and termination test data.
Need a certified rope and termination?
Send the selection and we will quote the construction, diameter, terminations and quantity.