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Wire & Cable ASIA – September/October 2007 64 January/February 2011
The object is to present profiled
material to the strander. The round
wire is re-shaped into the optimum
format for the desired strand con-
struction and finished cable size.
This roll form system can be as simple
as a two-layer (1+6) construction
or as intricate as a five-layer
(1+6+12+18+24) construction.
The scope of the strand design
determines the application confi-
guration; there are many different
designs available for each layer.
(a) Roll forming of the input wires.
This is achieved with a driven roll
stand shaping each wire in a layer
to a precisely designed shape.
(b) Round wire layers where a
number of round wires are closed
without any change in section.
Depending on the strand design, up
to four layers of roll forming strand
may be produced.
Each roll strand is driven individually,
allowing slight changes in speed
to be made at each position to
compensate for the variances in the
spiral length.
It further allows more precise distribution of wire tension
in each layer, optimising the straightness of the resulting
conductor.
The shaped conductors are formed into a compact unilay
strand using a high-speed double twist strander.
The machine is a side-loading unit equipped with a
standard floor loader, designed to load and unload the
take-up reel with minimum operator effort.
The scope of products that can be manufactured includes:
Copper and aluminium stranded conductors between •
8AWG and 600kcmil or 10mm2 and 300mm2
Bunched conductors to compact strand with fill factors •
between 76% and 97%
Aluminium conductors steel reinforced (ACSR) using •
a single steel wire core
All aluminium and aluminium alloy conductors (AAC •
& AAAC)
Cabling of insulated conductors •
Capital cost/
Twist $
Double twist
Strander
$
Tubular
Strander
$
Drum
Twister
$
Rigid
Strander
$
Planetary
Strander
Double Twist
Strander Tubular Strander Drum Twister Rigid
Strander
Planetary
Strander Factors
Capital cost/twist 1 3-5 7-16 9-12 16-24
“Working
factor”
Significant
(rigid)
Almost none
(planetary)
Significant
(rigid)
Significant
(rigid)
Almost none
(planetary)
Lay limitations Unilay only Not applicable None None None
Layer limitations Up to 4 layers 2 layers None None None
Typical payoff
package Stem Bobbin Stem Bobbin Bobbin
Payoff mode Continuous Required
loading cycle Continuous Required
loading cycle
Required
loading cycle
Single input wire schedules
Compact
Six wire sizes required using a conventional system
One wire size required using SIW system
Figure 1 ❍ ❍ : Close up of roll formers Figure 2 ❍ ❍ : Roll form unit and closing point
Figure 3 ❍ ❍
Figure 4 ❍ ❍ : Process cost/twist comparison