SGIA Journal Graphic November/December 2016 - 73

Print Quantity Matrix Chart (theoretical):

Typical PUC (print unit cost) levels compared for screen & digital printing
Each company's
variable overlapping
volume quantities

Screen1
Screen2

Print
Unit
Cost

Digital2
Digital1

Low
volumes

Medium
volumes

Large
volumes

Increasing print quantities

data sheets for ideal tension for quality
work. Despite the noted comparisons is
used as an analogy, it is not a stretch to
say under-tensioned screens are akin to
driving around with tires considerably
underinflated. This is why proper screen
tension is so important when trying to
acquire the utmost from the process.
Interestingly, when anyone sees their
car tires with an obvious loss of pressure,
the first thing the owner does is to drive
to the nearest garage and inflate them.
And there is a very good reason for this
sudden sense of urgency. Subconsciously,
they know only too well safety will be
compromised and, as a result, drive slower
than normal and even more cautiously in
adverse conditions until tires have been
properly inflated.
But what about the poor screen that
could also be equally "underinflated" as the
car tire? What is that weak tension going
to do with any print job if the ensuing
harmful influences of underinflated tires
directly affect ones' ability to drive or print
normally? The situation can potentially
lead to numerous printing issues, least of
all negatively affecting productivity and a
whole lot more. This way of operating is
not conducive nor profitable. If screening
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departments routinely operate in this
fashion, it means money is wantonly thrown
down the drain and opportunities lost,
particularly with lower-volume business.
For a screen to begin to perform
exceptionally well is no different from the
expectation of a properly inflated tire to
do the same on the road. Put into extreme
terms, four nearly flat tires will make the
car inoperable - period. This is not how
a quality-focused screen printing operation
should function and operate. Suitable screen
tension is the factor that begets initial overall
quality and productivity in the first instance.
Everything else that follows tension could
be considered as secondary at this point,
because none of their interrelating elements
can function properly if tension is not there
to begin with.
Coming back to our analogy, one may
now be wondering about the relationship
between tire pressure and cutting grass
with a riding lawn mower. Let me
explain. While the truck driver was
obviously aware of the value of using
correct tire pressure, he failed to practice
what he knew was fundamental in his
job. That became clearly apparent one
early evening when mowing his large
front lawn at home.
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As he was going on vacation the
following morning, he wanted to mow
the lawn while there was still some daylight
left. His mower was recently out of action
so his next-door neighbor kindly obliged
by lending him his riding mower. The
neighbor's mower worked and functioned
similarly to his own except for one small
detail (his words, not mine) - all four tires
were soft and close to being flat. Without
a compressor between them, the clock
ticking away, and not wanting to hurt his
neighbor's feelings, he went ahead and used
the mower just to get the job done before it
got too dark. That was his big mistake!
As you can well imagine, the mower
was very tough to control and took a lot
longer to complete despite newly sharpened
cutting blades. When finished, his lawn
looked an absolute mess. The mower's small
front wheels made large gashes as they dug
into the ground when making sharp turns
at the end of each pass. The large rear wheels
also did a great job of digging into the
surface, creating trench-like tracks over the
whole landscape - similar to a field that
has just been ploughed by a farmer.
The truck driver was obviously concerned
at first, but totally unware of the full extent
of the real damage until later. He then
November/December 2016 | 71
SGIA Journal Graphic November/December 2016

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