September 2nd, 2017
Non-Rotating Wire Ropes: A Basic Primer
A wire rope is a product of innovative and industrious use of steel wires. A wire rope is a collective construct manufactured from a number of individual wire strands, twisted around a centralized core.The wires are twisted around the core in a helical symmetry, in each strand. Every strand is a construct of individual wire components around a single or multiple wire center, in a wire rope.
Typically wire ropes are found in many configurations, and these configurations are decided by the construction techniques employed for manufacture of the wire ropes. The construction methodology used depends on the final application of the wire ropes.
Non- rotating, low rotation, and rotation resist are special types of wire ropes that employ specialized techniques like counter lay orientation in successive layers and the addition of die-forming techniques like swaging and compaction to achieve reduced rotation in the wire rope.
Non-rotating wire rope is typically used in applications that require hoisting and lifting with a variety of cranes.
Rotation is a property that is present innately in all types of wire ropes. A tendency to turn is seen, as a result of the torque incident on a length of rope tensioned, with both terminals fastened. Rotation in wire rope happens, when one terminal end is loaded but left unsecured. The net restoring forces within a wire rope cause rotation of the free loaded end. Rotation increases as the hoist height increases. Construction methodology of the wire rope determines to what extent rotation occurs.
Resistance to rotation:
This quality is achieved by employing one of the following manufacturing techniques. Lowering of rotation in a wire rope is determined by the type of wire rope selected and its final application.
Rotation resistant ropes:
Rotation resistant ropes are designed and constructed with two layers of strands laid helically around a core. The directional lay of strands in the outer layer being maintained in the opposite orientation to the lay direction of the layer beneath the first.
Parallel Closed Strands:
The parallel closing of the outermost strands, diminishes or closes the gaps incident between the strands in the outermost layer. This process consists of two layers laid in one closing process around a central core. The closed gaps between the strands result in increased metallic surface area and a bigger cross section, resulting in resistance to rotational forces.