Home' FLEXO iQ : September 2015 Contents 10 FLEXO iQ 2015 | ISSUE 3
Gold and silver
inks are a powerful
way of commu-
and luxury. Rotary
screen offers the
ability to apply a
range of metallic
effects, from fine
line work to solid
areas—e.g. for a
crest or a medal-
This provides a lean alternative to hotfoil and bypasses the need for
costlier metallized labelstock.
A WORKFLOW TO SUIT YOUR NEEDS
There are many options available with respect to the type of prepress
system and printing unit you install, and the types of screens you use.
The wealth of choice enables the printer to configure the workflow
according to budget, level of use, the type of printed effects required
and the end user markets supplied.
PREPRESS: DIRECT LASER ENGRAVING
Recently, direct laser engraving (DLE) has greatly simplified the way
screens are imaged. A dedicated rotary screen engraver features a
sealed CO2 laser that ablates the emulsion from the image areas on the
screen without the need for film, chemicals or drying. The precision
of the laser, together with the software, optimizes the control when
creating fine positive and negative images, and resolutions up to 4,000
dpi. Print width dependent repeat sizes range from 10-in. to 36-in.
MODULAR VS INTERCHANGEABLE
Adding rotary screen technology does not require investment in a
new press. One can enhance an existing press with modules or lighter,
easily changeable cassette units.
A printing module can be installed on a sliding rail system above the
press. The rail system allows easy repositioning of the module, man-
ually, to any position in the printing sequence: primary for opaque
white; secondary for varnishes, for example. Module widths can range
from 10-in. to 40-in. and offer a wide range of repeat sizes. Lighter,
roughly 80-lb. modules with restricted repeat ranges may offer better
investment return for dedicated narrow web printing situations.
Cassette units, suited for the latest generation of narrow web presses,
allow fast change of print processes at each station of the printing
sequence. These are approximately 55-lbs. or lighter and can be slotted
in and out safely by the operator, in minutes.
The quality of the screens has significant impact on total ownership
costs. Screen cylinders featuring nickel, electroformed non woven
meshes offer the highest levels of strength and stability, and optimum
ink flow. Thus they can run smoothly without risk of breaking or clog-
ging at speeds of up to 450 fpm, depending on application. They also
have longer printing lifespans, can be reused several times and can be
reimaged for new jobs.
Alternatively, a non woven nickel screen can also be supplied as a flat
mesh, for the printer to assemble in house, into a cylinder. This mesh
is supplied as a precoated, light sensitive plate. These low cost, home-
made rotary screens can be used several times for printing a single
image, making them an ideal solution for repeat jobs.
The higher the mesh count, the more detailed the feature: A range of
screens is available, catering to everything from coarse effects to fine
line work and Chinese or Arabic text.
Finally, innovations from ink suppliers are strengthening the competi-
tiveness of the rotary screen process. New LED UV curable inks allow
faster, safer and energy efficient curing, while low migration inks
assure safety for food and pharmaceutical packaging applications.
ROTARY SCREEN TECH PROVIDER QUALITIES
A supplier with experience in providing technology at all stages of the
workflow, who also has partnerships with a wide range of press makers,
is likely to guide the printer to the optimal solution to the circumstances
and oversee a smooth integration. A global network and the resources
to offer training, testing of new ideas, screen imaging and fast, ongoing
technical support on a worldwide basis are arguably essential features to
look for when choosing a long term technology partner.
In summary, rotary screen printing, as a complement to the UV
flexo process, enhances the chances of brand success with numerous
appealing effects. With guidance and ongoing support from the tech-
nology provider, the printer is best placed to offer bespoke and more
exciting branding solutions with a workflow configured to make a fast
investment return. n
About the Author: Bas Hoijtink is commercial manager graphics and
security printing at SPGPrints in Boxmeer, Neth-
erlands, responsible for developing the company’s
global graphics and security business. Previously, as
marketing manager for a multinational consumer
goods distributor, Bas was responsible for marketing
several global wines and spirits brands.
Electroformed nickel RotaMesh screens offer strength
and stability to run at high speeds and can be
reimaged for different jobs.
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