06.14.2021 Wire Rope
The rope core can be classified into the fiber core and the steel core.
(1)Fiber core(abbreviated as FC)
The fiber core has two important functions, or ① to support the strand and at the same time to hold the shape of the rope, and ② to hold the rope grease and to supply the necessary amount of grease to the inside of the rope, during use, for lubrication and to prevent corrosion.
In the past, natural fiber was mainly used but, of late, synthetic fiber is starting to be used. Two kinds of natural fibers are used, one is the hard fiber, such as Manila and saisal, as well as jute and the other is the soft fiber, such as cotton threads, used in ropes with a comparatively small diameter.
Also, for synthetic fiber, specially processed polypropylene is used so that the synthetic fiber will hold the grease well.
The characteristics of fiber core compared to steel core are
(b)superior shock resistance
(c)Holds rope grease well (in particular, in the case of natural fiber)
(d)The unit and mass of the rope is small. Moreover, synthetic fiber compared to natural fiber is superior in corrosion resistance.
For steel cores, there is the strand core (IWSC) and the rope core.
Among the rope cores, there is the IWRC and the CFRC(center fit wire rope core).
(a) The IWSC (indepent wire strand core) has the strand as the core and those which have the same construction as the side strand are called as the common core.
(b)The IWRC (independent wire rope core) has a single independent rope as the core. Usually, a 7×7 construction is used but depending on the use a 6×7 or a 6×19 may be used.
(c)For the CFRC (center fit wire rope core), the outer layer strand of the core rope is fitted into the groove of the inside of the side strand of the rope. This core rope is positioned in one process with the outer layer rope. Moreover, for the core rope, the 7×7 and the 19+8×7 are used.
The IWSC and the CFRC are used in only a few special cases. Among ropes with a steel core, the IWRC has a good flexibility and so is used the most. The characteristics of the steel core are as follows compared to the fiber core.
(a)The rope has a high strength.
(b)High resistance for lateral pressure and deformation.
(c)The elongation of the rope is small and the change of diameter is low.
(d)Superior heat resistance
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