Wire Ropes, Elements and Definitions - Wire Ropes: Tension, Endurance, Reliability - page 29

1.3 Rope Cores

The rope core is the central element of a round rope around which are laid helically
the strands of a stranded rope. The different types of cores are listed in Table 1.5 .
They are usually made of fibre or wires. For dimensioning of fibre cores see
Sect. 1.6.3 and of steel cores Sect. 1.6.4 .
Fibre cores (FC) can be made either natural fibres (NFC) or synthetic fibres
(SFC). They are normally produced in the sequence: fibres to yarns, yarns to
strands and strands to fibre rope. In Fig. 1.28 different fibre cores are shown,
Singenstroth ( 1984 ). Fibre cores have the advantage that they can store a relatively
large amount of lubricant. The strands are supported softly. The fibre core should
be well rounded and without any knots.
During the life of a wire rope, the diameter of the fibre core will be reduced.
According to Singenstroth ( 1984 ) and Sivatz ( 1975 ), the diameter loss is about
3-5 % for natural and polypropylene fibre cores and about 0.5-1 % for polyamide
fibre cores. Therefore, the clearance between the strands must be large enough to
prevent any strong pressure arising between them. The endurance of the wire rope
is influenced to a great extent by the dimension and the form of the fibre core, see
Sect. 3.2.3 , Wolf ( 1987 ).
Steel cores (WC) are made from steel wires arranged as a wire strand (WSC) or
normally as an independent wire rope (IWRC). A strand core is only used for very
small ropes or for multi-strand ropes. The steel wire rope core can either be

Table 1.5 Symbols for rope cores based on ISO 17893

Fibre core Fibre core FC

Natural fibre core NFC

Synthetic fibre core SFC

Steel core Steel core WC

Wire strand core WSC

Wire rope core WRC

Independent wire rope core IWRC

Independent wire rope core with compacted
strands

IWRC(K)

Independent wire rope core covered with a
polymer

EPIWRC

EFWRC a Wire rope core enveloped with fibres

ESWRC a

Wire rope core enveloped with solid polymer

Steel core in parallel-closed rope Parallel steel core with strands PWRC

Parallel wire rope core with compacted strands PWRC(K)

Multi-strand rope (rotation-
resistant)

Fibre centre FC

Wire strand centre WSC

Compacted wire strand centre KWSC

a

Supplement, not listed in ISO 17893