WCA March 2012

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Wire & Cable ASIA – March/April 2012 54
ONLINE recording of production data
has always played an important role in
cable production. In the past data was
collected separately at every single
production line. Therefore, simple plant
computers were used in combination
with a printer for extensively printing
out the data at the end of the
production process. In particular, data
archiving was a major problem.
Nowadays, the measuring values are
recorded and stored digitally in real
time. This is especially important with
regard to the high capacity of the lines
and the related data volume. There are
two possibilities of data processing.
On the one hand, production data is
measured online and directly
transferred to a central quality
assurance system. As there is often
measuring data of several production
lines available to the operator, a line
computer is quickly at its capacity
limit.
That is why measuring data is first
collected and processed in processor
systems such as the Sikora Ecocontrol
before being transferred to a line
computer. Data can be stored daily,
batchwise but also reelwise.
The processor systems determine
trends and statistics over the entire
production process and document
quality characteristics of the product
for defining Cp or Cpk values. In
addition, they provide information on
possible surface faults on the cable
such as lumps and neckdowns.
The online processing and recording of
quality characteristics is a significant
progress for the cable production
compared to the past.
Five years ago, a cable manufacturer
could make a statement about
statistical data. However, he had not
received details on the single values as
they were averaged.
Therefore, a cable could be shown
concentric in the average value,
although it was punctual eccentric.
Only by means of a cut cable sample
could the operator recognise that the
core was eccentric in the insulation
and the cable did not fulfil quality
requirements.
Nowadays there are solutions such as
the so-called cloud diagram, which
graphically present the distribution of
short-term variations of the
eccentricity. The information is stored
and transferred to a line control via
serial interfaces or simply by a USB
stick.
As a result, the operator and the
quality management continuously have
production data available for
monitoring processes and improving
them with the help of QS quality
documentation.
Sikora AG – Germany
Fax:
Email:
Website:
Data processing
and recording in
extrusion lines
▲
▲ The cloud diagram is an alternative
style visual view of the measurements
being made at the processor system
Ecocontrol. With the help of the cloud
diagram the distribution of the
short-term variations of the eccentricity
are shown. The cloud consists of 5,000
dots, whereby each dot represents an
actual single value of the eccentricity
(value and direction). The overall
distribution of the cloud diagram easily
highlights the standard deviation of the
eccentricity