What is bird-caging in wire rope and what causes it?

• A. A formation where strands separate and splay outward due to overload or damage; indicates rope failure risk.
• B. A locking mechanism that prevents strands from separating.
• C. A term for properly lubricated rope.
• D. A method of coating rope for corrosion protection.

Answer: (A)

Bird-caging is when the strands in a wire rope loosen and splay outward, giving a cage-like appearance around the rope. This happens when the rope has been overloaded or damaged, causing inner strands to shift and outer strands to buckle under load. Severe bending, shock loading, wear, or core damage can initiate it, and as the strands separate the rope loses stiffness and load-bearing capacity. It’s a clear warning that the rope is nearing failure and should be taken out of service before a sudden break occurs. The other descriptions don’t fit because bird-caging isn’t a locking mechanism, nor a sign of proper lubrication or protective coating.