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3.7.1 Usage and application of printed top web
This discusses how the tolerance of the repeat print design on packaging material for Repak
Roll stock machines is determined.
The tolerance is depending on the properties of the packaging material and the manner it is
used on the machine.
The supplier of the packaging material is always responsible for the repeat of print design.
These data only applied to:
Repak Roll stock machines.
on condition that:
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the machine is in good condition
-
the machine is equipped with the following:
-
suitable unwinding system, (core diameter, max roll diameter)
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suitable drive for film transport
-
photocell with film brake
3.7.2 Explanations of notions
Repeat print
Print design with repeating distance between each print.
Repeat length “a”
Adjusted distance between two consecutive prints.
The repeat length “a” is identical to the stroke length in the format
drawing.
Tolerance repeat
Relative total deviation “Δ U” and absolute individual deviation
length
“Δ a”
Relative total
actual value (mm)
– adjusted value “a” (mm)
deviation
Δ U
----------------------------------------------------------- x 100%
adjusted value “a” (mm)
The actual value results as an average of:
-
measurement of 3 or more repeat lengths, (at least over 1 meter).
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The measured value must be wholly divisible by the number of repeats.
Absolute indivi-
Δ a = a (n) – a (n +1) (mm)
dual deviation
= Deviation between 2 consecutive repeats in mm