A steel wire rope looks simple, but the same 16 mm rope can be stiff or flexible, crush-resistant or prone to spinning, depending on how it is built. This guide explains the parts of a wire rope specification so you can order the right rope the first time.
How a wire rope is built
Every steel wire rope has three parts:
- Wires: the smallest element, drawn from high-carbon steel.
- Strands: wires twisted together in a set pattern.
- Core: the centre that the strands are laid around. It supports the strands and keeps the rope round under load.
A construction such as 6x19 means 6 strands with 19 wires in each strand. More, thinner wires make a rope more flexible; fewer, thicker wires make it more resistant to abrasion and crushing.
How to read a wire rope specification
A complete order line looks like this: 16 mm 6x36 IWRC 1770 RHOL galvanised. Each part means something:
| Part | Meaning |
|---|---|
| 16 mm | Nominal diameter, measured across the outer crowns of the strands |
| 6x36 | Construction: 6 strands of 36 wires (the 6x36 class also covers 6x26, 6x31, 6x41 and 6x49) |
| IWRC | Core type: Independent Wire Rope Core (a small steel rope in the centre) |
| 1770 | Tensile grade of the wires in N/mm² |
| RHOL | Lay: right-hand ordinary (regular) lay |
| Galvanised | Finish: zinc-coated wires (the alternative is bright, ungalvanised rope) |
Common constructions and where they are used
| Construction | Character | Typical uses |
|---|---|---|
| 6x7 (6/1) | Few thick wires: stiff, very abrasion-resistant | Mining, haulage, logging, well drilling |
| 6x19 class | Balance of flexibility and abrasion resistance | General engineering, winches, elevators, slings |
| 6x36 class | Many fine wires: flexible, bends well over sheaves | Cranes, hoists, drilling, marine |
| 6x24 / 6x12 FC | Fibre-cored, light and flexible | Mooring, towing, cargo lashing |
| 17x7 / 18x7 | Rotation-resistant (multi-layer strands) | Single-fall crane hoist lines |
The full breaking-load tables for each of these are on our wire rope specification tables, searchable by diameter.
Fibre core, IWRC or WSC?
A fibre core (FC) makes the rope lighter and more flexible, and holds lubricant. A steel core, either IWRC or a single-strand WSC, gives higher strength and much better resistance to crushing on drums. In our catalogue tables a 16 mm 6x19 rope at 1570 N/mm² has a minimum breaking load of 124 kN with a fibre core and 133 kN with a steel core, about 7% more. Choose a steel core for cranes, multi-layer drum winding and heat; choose fibre core where flexibility and light weight matter more.
Tensile grade
The grade is the strength of the individual wires. Common grades are 1570, 1770 and 1960 N/mm². A higher grade gives a higher breaking load at the same diameter, but the wires are slightly less tolerant of bending fatigue and abuse. For most crane and general lifting work 1770 is the standard choice.
Regular lay or Lang's lay?
In regular (ordinary) lay the wires are twisted opposite to the strands. It is stable, resists crushing and is easy to handle, which is why most ropes are regular lay. In Lang's lay the wires and strands are twisted the same way. It gives better abrasion and fatigue life, but it must have both ends fixed or it will untwist. Right-hand lay is standard; left-hand lay is ordered for specific drum or pairing needs.
Galvanised or bright?
Bright (ungalvanised) rope relies on lubricant for protection. Galvanised rope has zinc-coated wires and lasts far longer outdoors, near the sea or in damp plants. For very corrosive or hygienic environments, stainless steel rope is the next step up. See stainless vs galvanised vs PVC-coated wire rope for a full comparison.
Standards to ask for
General-purpose steel wire ropes in India are covered by IS 2266. Internationally, ISO 2408 and EN 12385-4 cover stranded ropes for general lifting. Ask for a Mill Test Certificate (MTC) with every lifting rope so the breaking load and grade are documented. We provide MTCs on request; see our certification page.
Checklist before you order
- Diameter and length required (allow for drum wraps and terminations)
- Application: crane, winch, sling, guy, haulage
- Construction and core, or the old rope's marking if you are replacing it
- Tensile grade, lay direction and type
- Finish: bright, galvanised or stainless
- Certificates: MTC, third-party inspection
Frequently asked questions
What does 6x19 mean in wire rope?
6x19 means the rope has 6 strands with 19 wires in each strand. It is a general-purpose construction that balances flexibility with resistance to abrasion.
What is IWRC in wire rope?
IWRC stands for Independent Wire Rope Core: a small steel wire rope at the centre of the main rope. It gives higher strength and better crush resistance than a fibre core.
Which wire rope is best for cranes?
Most cranes use a flexible 6x36 class rope with a steel core (IWRC). Single-fall or high-lift cranes often need a rotation-resistant rope such as 17x7 or 18x7. Always follow the crane manufacturer's rope specification.