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Technology
news
Wire & Cable ASIA – January/February 2012
52
Manufacturers today face a
number of production challenges based
around productivity, quality and cost
reduction. At the centre of this challenge,
is the ability for manufacturers to
accurately measure the length and
speed of wire and cable in order to
better control sequential printing or
marking operations.
Traditionally, manufacturing plants have
used mechanical type encoders, such as
contact rotary encoders or tachometers,
to measure the length and speed of wire
and cable during production in order to
control the sequential printing on
products. The outer coatings of cables
are typically marked with details
including product length in the form of
metre or footage marks, manufacturer’s
name,
product
and
operating
information.
Wires may indicate special numbering or
coding for identification
purposes. Customers rely
on the accurate spacing
of this information to
ensure the manufacturer
delivers the exact amount
of product as specified.
Customers also rely on
the accuracy of this
information to perform
critical tasks, such as
laying the correct amount
or length of wire or cable
without
needing
to
re-measure it.
But contact encoders are prone to
mechanical and calibration problems
which result in costly measurement
errors. As such, wire and cable
manufacturers
are
looking
to
non-contact measurement methods
such as the LaserSpeed encoder from
Beta LaserMike to accurately measure
the length and speed of product during
sequential
printing
applications.
Manufacturers are realising productivity
gains with this technology by
significantly reducing measurement
errors and improving process control.
This article gives an inside look.
Contact
encoders
face
real
measurement challenges during
production
Depending
on
the
application,
mechanical contact-type encoders face
a number of challenges in wire and cable
production processes. First, mechanical
encoders must contact the wire or cable
in order to measure the length and
speed of product during production.
These measurements are indirect
measurements, relying on the physical
contact between the mechanical
encoder wheel and the product’s
surface. Length is calculated from the
amount of rotation of the contact wheel.
However, contact encoders by their very
nature have several fundamental flaws
that make them prone to measurement
errors.
Contact encoders are subject to
slippage and calibration changes caused
by variations in the diameter of the
contact wheel due to dirt build-up or
wear. Since the contact encoder is a
mechanical device, it also experiences
mechanical component failure from time
to time – requiring repair and
re-calibration.
The measurement error of
mechanical systems will
also
change
with
production
conditions,
requiring the line operator
to continuously check the
spacing of the print and
then
recalibrate
the
contact encoder to keep
the
marks
within
specification. Product
length
and
speed
inaccuracies may be as
much as 2%, or even
greater, depending on the
application.
Products such as CAT, CV, power,
telephone, and other types of cables are
very expensive to produce, and
manufacturers produce millions of feet
or metres of wire and cable product
monthly. A two per cent measurement
inaccuracy on this large amount of
The non-contact laser
makers to accurately mark
▲
▲
LaserSpeed non-contact length and
speed encoder
▲
▲
Contact method is prone to
measurement errors