3D Model — Orbit & Inspect
Anatomy of a Wire Rope
Core
The central support around which strands are laid. Can be Fibre Core (FC) for flexibility or Independent Wire Rope Core (IWRC) for strength and heat resistance.
Strands
Groups of individual wires twisted together in a helical pattern. A 6×19 rope has 6 strands, each containing 19 wires. More wires per strand = more flexible.
Individual Wires
High-carbon steel wires that provide the actual tensile strength. Wire diameter determines rope flexibility vs strength.
Lay Direction
Regular lay: wires and strands twist opposite directions (most common). Lang lay: same direction (more flexible but prone to unlaying).
Thimble
Metal eye fitting inserted into the rope loop to prevent the eye from being crushed under load. ALWAYS required in sling eyes.
Ferrule / Swage
Aluminium or steel sleeve pressed (swaged) onto the rope to form a permanent eye termination. Must be machine-pressed — never hand-crimped.
Common Constructions
| Type | Use | Flexibility |
|---|---|---|
| 6 × 19 | General purpose lifting | Medium |
| 6 × 24 | Running ropes, cranes | Good |
| 6 × 36 | Multi-layer drums, tight bends | High |
| 6 × 7 | Standing ropes, guys | Low (stiff) |
Rule of thumb: More wires per strand = more flexible but less abrasion resistant. Fewer wires = stiffer but better wear resistance.
WLL Calculation
Working Load Limit for FSWR slings with IWRC (6×19 construction):
Single Leg Vertical
D = rope diameter in mm • Result in kg
| Diameter | WLL (Single Vertical) | WLL (2-leg 60°) |
|---|---|---|
| 8 mm | 614 kg | 1,064 kg |
| 10 mm | 960 kg | 1,663 kg |
| 12 mm | 1,382 kg | 2,394 kg |
| 16 mm | 2,458 kg | 4,256 kg |
| 20 mm | 3,840 kg | 6,651 kg |
Temperature Limits
| Core Type | Max Temp | Effect |
|---|---|---|
| Fibre Core (FC) | 95°C | Fibre degrades, loses internal support |
| IWRC | 200°C | Steel core maintains strength longer |
Critical Warning
- Never use FSWR that has been exposed to temperatures above its rated limit
- Heat-affected rope loses strength permanently — it cannot be “cooled down” and reused
- Discolouration (blue/brown tint) indicates heat damage — remove from service immediately
Inspection & Rejection Criteria
Inspect FSWR slings before every use. Remove from service if ANY of the following are found:
Reject Immediately If
- Broken wires: 5% of total wires broken in any one rope lay length
- Corrosion: visible pitting or rust on wires
- Kinks: any permanent deformation from mishandling
- Birdcaging: strands forced outward creating a cage shape (from shock load)
- Crushing: flattened cross-section from being trapped under load
- Heat damage: discolouration, melted fibres, or loss of lubricant
- Ferrule damage: cracked, deformed, or slipping ferrules
- Missing/illegible tag: no identification = no use
- Core protrusion: core visible between strands
- Reduction in diameter: >5% from nominal = internal wear
Good Condition Indicators
- All wires intact, no broken wires visible
- Rope well-lubricated, no dry or rusty sections
- Ferrules/swages intact and unmarked
- Thimbles seated properly in eyes
- ID tag legible with current test date
- Uniform diameter throughout length
Slinging Methods & Factors
| Method | Factor | Use Case |
|---|---|---|
| Single vertical | 1.0 | Direct vertical lift |
| Choker hitch | 0.8 | Wrapping around load |
| Basket hitch | 2.0 | U-shape under load |
| 2-leg @ 60° | 1.73 | Standard bridle |
| 2-leg @ 90° | 1.41 | Wider spread |
| 2-leg @ 120° | 1.0 | Maximum safe angle |
Never Exceed 120° Included Angle
- At 120° each leg carries the FULL load weight
- Above 120° sling legs are being pulled apart — catastrophic failure risk
- Use a spreader bar if the load requires a wider attachment
Storage & Handling
- Store on racks or hooks — never on the ground where moisture collects
- Keep away from chemicals, acids, and salt water
- Do not drag over sharp edges — use edge protectors
- Do not tie knots in wire rope — permanent damage to wires
- Coil properly when not in use — do not kink
- Re-lubricate periodically per manufacturer’s instructions
- D:d ratio minimum 20:1 (rope diameter to bend radius)
- Tag and quarantine defective slings immediately — do not place back in service