EuroWire November 2016

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Technical article
November 2016 56
Manufacturing of compact
conductors, highlighting
the benefits and potential
cost reductions in the whole
stranding process
By Sean Harrington, Ceeco Bartell Machine Systems LLC
Introduction
Ultimately, every cable manufacturer aims
to make a quality product using the least
amount of resources in the fastest time. To
do this, they must understand the critical
parameters that affect the strand they
wish to make.
Once this is accomplished, finding the
hardware to provide them with the most
flexible and effective process is relatively
easy.
The aim of this paper is to present a
technological solution in the process of
the manufacture of compact conductors,
which brings cost savings from the wire
drawing process through the cabling and
into the extrusion process.
This is the use of the roll form technology,
which allows the use of a single input
diameter wire to be utilised throughout
the stranding process, giving significant
process savings and advantages.
Traditionally, a finished stranded
conductor requires its own drawn wire
diameter.
Each wire diameter typically requires
a new string up in the wire drawing
machine. Some conductor designs require
more than one drawn wire size.
Similarly, multiple set-ups in the stranding
process are necessary for each size of
conductor. The set-up time taken on both
the drawing and stranding machines,
combined with inventory levels that are
necessary to manage the number of
wire diameters, represent unnecessary
activities that add to the conversion cost
from rod to strand.
The SIW mentality effectively eliminates
much of this unnecessary activity
associated with the traditional set-up by
using the same drawn wire diameter to
finish a range of stranded conductors.
The result is:
• Increased wire drawing output
• Reduced wire drawing die inventory
• Reduced scrap
• Significantly lower work in process
• Minimum strander payoff changes
• Increased strander output
• Shorter lead times
• Enhanced JIT manufacturing mentality
• Streamlined overall stranding process
Probably more to the point is a significant
reduction in the variables that the
manufacturer needs to manipulate in the
manufacture of any strand programme.
The change in philosophy that is required
to effectively use single drawn wire
diameter to produce the required range
of finished strand conductors is to replace
the flexibility of stranding the same
number of wires using different diameters
with stranding different numbers of wires
using the same wire diameter.
In general, the benefits of the SIW
mentality are independent of the strand
manufacturing process used. It is only
when the specific strand designs have
been defined and the production
requirements of those designs are
determined that the choice of the
optimum manufacturing cell can be
considered.
It should be noted that the concept of
using a single input wire to manufacture
a range of finished conductor sizes
is not new; it is used within the confines
of most manufacturing plants within
the allowances of the current
specifications.
It has been used extensively in Europe
where strand programmes using the
single input wire diameter to cover a range
of finished conductor sizes has been in
existence for decades.
The potential cost reductions using this
process can be split into the following
areas:
• Process savings
• Material savings
Process Savings
The obvious impact of the incorporation of
roll forming into the stranding process is
shown in Figure 1.
While still working within the constraints
of the IEC and ASTM standards, the roll
forming process allows the number of
wires required to produce a range of
conductors to be reduced dramatically.
In this case, to cover 35mm2 to 240mm 2
the number of wires has been reduced
from eight to two.