A wire rope is a piece of
flexible, multiwired, stranded machinery made of many precision parts.
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IWRC (independent
Wire Rope Core) provides good crush resistance and increased strength. |
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Fiber Core provides excellent
flexibility |
Usually a wire rope consists of a core
member, around which a number of multiwired strands are "laid" or helically
bent. There are two general types of cores for wire rope fiber cores and wire cores. The
fiber core may be made from natural or synthetic fibers. The wire core can be an
Independent Wire Rope Core (IWRC), or a Strand Core (SC).
The purpose of the core is to provide support and maintain
the position of the outer strands during operation.
Any number of multiwired strands may be laid around the
core. The most popular arrangement is six strands around the core, as this combination
gives the best balance.
The number of wires per strand may vary from 3 to 91, with
the majority of wire ropes falling into the 7-wire, 19-wire, or 37-wire strand categories.
Understand what the "lays" of wire rope mean
"Lay" of a wire rope is simply a description of
the way wires and strands are placed during construction. Right lay and left lay refers to
the direction of strands. Right lay means that the strands pass from left to right across
the rope. Left lay means just the opposite: strands pass from right to left.
Regular lay and lang lay describes the way wires are
placed within each strand. Regular lay means that wire in the strands are laid opposite in
direction to the lay of the strands. Lang lay means that wires are laid in the same
direction as the lay of the strands.
Most of the wire rope used is right lay, regular lay. This
specification has the widest range of applications and meets the requirements of most
equipment. In fact, other lay specifications are considered exceptions and must be
requested when ordering.
Here are some exceptions
Lang lay is recommended for much excavating, construction,
and mining applications, including draglines, hoist lines, dredgelines and other similar
lines. Here's why. Lang lay ropes are more flexible than regular lay ropes. They also have
greater wearing surface per wire than regular lay ropes.
Where properly recommended, installed and used, lang lay
ropes can be used to greater advantage than regular lay ropes. However, lang lay ropes are
more susceptible to the abuses of bending over small diameter sheaves, pinching in
undersize sheave grooves, crushing when winding on drums, and failing due to excessive
rotation. Left lay rope has greatest usage in oil fields on rod and tubing lines, blast
hole rigs, and spudders where rotation of right lay rope would loosen couplings. The
rotation of a left lay rope tightens a standard coupling.
