PRODUCT NEWS
Testcut process for repeat-accurate
cylinder engraving
HELL GRAVURE SYSTEMS ■ CellEye
is a new testcut process for HelioKlischograph systems that ensures
outstanding repeat accuracy for
packaging gravure cylinders. It calculates the actual volume of the
engraving cell, factoring in the real
stylus angle and stylus wear. It compensates for variations in the engraving copper that can occur from
cylinder to cylinder. CellEye also
enables users to control the highlights, midtones and shadows separately from each other. The testcut
process used by CellEye has already
proved excellent in illustration gravure and made engraving tolerances in the ribbons superfluous.
The advantages of CellEye include repeat-accurate cylinder engraving that factors in the real stylus angle and is unaffected by stylus
wear and copper variations, separate control of highlights, midtones
and shadows, reliable colour results
for originals in proof and print,
dramatic reduction in waste thanks
to much simplified colour matching
on the press and increased service
life of engraving styli.
Figure 1:
The cell was recorded by
measuring the longitudinal
and cross diagonals.
Figure 2:
The old method does not
take adequate account of
geometric distortions in a
cell.
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Factoring in the specified
stylus angle
Applications
The accuracy of the stylus angle has
a considerable influence on the result of the volume calculation.
Some manufacturers of engraving
styli now specify the real measured
angle for each engraving stylus, e.g.
119.8° or 120.1° for a 120° stylus.
The manufacturer’s specifications
for the real stylus angle can be
transmitted to the touchmemory of
the engraving head of a HelioKlischograph (must be K500 NT
model 2004, HelioControl2 2.1,
Touchmemory Version 14) and is
from then on factored in on all
machines equipped with CellEye.
Principle
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The use of CellEye in conjunction
with SprintEasy 2 measuring station provides the best results when
it comes to repeat accuracy of engraving cylinders (figure 5).
Engraving styli are subject to
wear that is also reflected in a
change of stylus angle, which can
be as much as +4°. With the SprintEasy 2, the current stylus wear is
recorded and the changed stylus
angle transmitted directly to the
touch memory of the engraving
head. The repeat accuracy of the
cylinder engraving is therefore assured, even with a highly worn
stylus. This means that with SprintEasy 2, the service life of engraving
styli can be significantly increased.
The station also offers users further
benefits. Slide shoe setting can be
performed very quickly and accurately outside the HelioKlischograph. There is no longer any need
for »scratch tests« on a test cylinder
and the accompanying risk of
breaking the stylus.
the midtones.
The old testcut process evaluated
only the linear dimensions of the
testcut cell (figure 1).
As figure 2 demonstrates, the
length and width of different cells
can match even though their forms,
and therefore their volumes, are
different. It is therefore also to be
expected that the printing densities
achieved in each case will be different.
The new testcut process with
CellGuard 3 determines the volumes of the testcut cells. The cell is
cut into numerous thin slices (figure
3).
With the help of the stylus geometry, the volume of each individual
slice can now be calculated (figure
4). The sum of all the slices’ volumes
yields the volume of the entire cell.
Until now, the vibration setting in
packaging was implemented by
specifying highlight, shadow and
Figure 3:
channel for the testcut cells. The
CellEye divides the cell into mid-tones could not be kept connumerous slices.
stant using this process. CellEye is
the first system to allow users to
Figure 4:
define highlight, midtone and
CellEye calculates the
shadow separately from each other
volumes of the slices and
determines the cell volume. and therefore also enable control of
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Even better results
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Using CellEye enables repeat-accurate cylinder engraving, reliable
colour results in proof and print and
a dramatic reduction in waste.
Some example may demonstrate
this.
● Follow-up orders. Frequently,
only one cylinder out of a cylinder
set is re-engraved e.g. because of a
change to the text. CellEye ensures
that exactly the same results are
achieved later as with the original
cylinder.
● Test and production cylinders.
Sometimes, test engravings are performed before the actual production
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FLEXO & GRAVURE ASIA 4-2007
© by G&K TechMedia GmbH · D-79261 Gutach · www.flexo-gravure-asia.com
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engraving. CellGuard 3 ensures
that exactly the same results are
achieved on the production cylinder as those produced earlier on the
test cylinder.
● Engraving ranges of packaging.
A new product is to be offered in
two different sizes of packaging.
One cylinder set is engraved for size
A and another for size B. Job A is
sent to the press first. The colours
are fine-tuned on the press, a process that by its very nature leads to
hundreds of meters of waste printouts. The job then goes into production. After this, the cylinders for job
B are installed. Because the cylinders of job A and job B demonstrate
identical print behaviour thanks to
CellEye, no fine-tuning of colours is
necessary for this job. There is no
waste. This saves considerable
amounts of ink and substrate.
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PRODUCT NEWS
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It is, in principle, possible to run
HelioKlischograph systems in mixed operation with and without
CellEye. However, one cylinder set
should always be completely engraved using the new process, as
this is the only way to take full
advantage of the benefits of this
method.
Figure 5: The new CellEye function
forms an ideal addition to SprintEasy 2.
Requirements and
availability
CellEye is keycode protected and
compatible with the HelioKlischograph K500 NT (2004 model) and
will be supplied as standard with
immediate effect. However, the
conventional process is also supported in parallel. It requires HelioDisk Version 4.0, HelioControl2
Version 2.0 (or 2.1 for manual input
of the stylus angle) and HelioSprint
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FLEXO & GRAVURE ASIA 4-2007
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engraving systems with Touchmemory Version 14. Customers
with a software support agreement
will receive CellEye free of charge.
Customers without such an agreement can retrofit CellEye with a
software upgrade.
➜ www.hell-gravuresystems.com
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