Rope Services Direct supplies a variety of anti-spin non rotating wire rope (also called rotation resistant wire-rope). All standard wire-rope has a tendency to develop torque and therefore prone to rotation.
Non-rotating wire ropes are designed so that the wire-rope outer rotational force naturally counteracts the inner strands rotational force in the event that a rope is subjected to a load.
Various classes of non-rotating wire-rope are available such as 18×7 and 19×7. Call us today on 01384 78004 to discuss your application and we can advise on a great anti-spin wire-rope solution for you.
Why use Non Rotating Wire Rope
When a load or force is attached to a standard rope the forces will cause the rope to elongate and rotate, therefore spin the load, quite possible out of control, this can be a dangerous practice, especially for heavy loads and loads lifted from a great height such as on a pillar crane. When the rope rotates in this way the strands will begin to unravel, loosing strength and the rope will undoubtedly fail, this could be catastrophic. It is for these reasons that non rotating rope is commonly used for many types of lifting applications including main hoist rope, whip rope, crane rope, off-shore and deck rope and more.
Non rotating wire rope or rotation resistant wire rope has a different construction to standard wire rope. Rather than all wires and strands being laid in the same direction, a rotation resistant wire rope consists of inner strands being laid in the opposite direction to the outer layers, for example the inner may be constructed in left hand lay whilst the outer layer is in right hand lay. The nature of this construction means that torsional forces on the inner and outer wires/strands will counteract each other and so minimise the risk of unravelling.
It is worth noting that the number of strand layers will have an effect of the resistance of rotation. A 2 layer rope has less resistance than a 3 layer rope, therefore the more layers the rope has the greater rotation resistance it will have.
These types of ropes can be classified as spin resistant, rotation resistant or non rotation resistant; they are classed on the basis of the number of rotations a certain length of rope does when a force of 20% of the MBF is applied; with 1 turn or less the rope will be classified as non rotating; with rotations between 1 & 4 the rope is classed as low rotation and for rotations between 4 & 10 the rope will be classified as spin resistant, any higher and the rope is NOT rotation resistant at all.
Care & Handling of Rotation Resistant Wire Rope
Non rotating or rotation resistant ropes need to be used and handled with care, they are often deemed to be less stable than conventional wire ropes, this is due to the friction on the inner wires caused by the strand cross over’s which will eventually cause the inner wires to break up, this is more apparent on non rotating wire rope with two layers. Ropes with 3 or more strand layers will distribute the radial pressures more evenly, and reduce friction and stress on the inner wires.
Regular, thorough inspections of non rotating rope are essential due to the fact that it is the inner strands that often break first and broken internal wires often go unnoticed as they are difficult to see. Here at Rope Services Direct we offer inspections on all rope with certification issued on completion.
Shock loading should be avoided with rotation resistant wire rope as this can cause rope distortions, bird caging and core protrusion where the inner strands/core extend out from the outer layer.
Both ends of the rope should be seized correctly to prevent the strands from unwinding. Any end fittings should be carefully fitted to prevent damage to the rope such as kinking and unravelling; they can also have an effect on the rotational balance if not fitted correctly.
Rope Services Direct can supply non rotating wire rope to your specifications at the most reasonable prices so call us today on 01384 78004.