Adjustment of Ink and Water Supply in Offset Printing

Abstract

The stochasticity of the ink-water balance in the offset printing process is actually a fact. We have only the rotating speed of the duct dampening roller adjustment to apply the water to the printing plate, and against we have the ink zones which can be opened differently depending on the printing elements quantity. This means that in any way of settings we will definitely have a certain constant amount of water emulsified in a different quantity of ink. This should be so far acceptable as long as we have the wide-latitude inks in terms of tackiness, water acceptance and other rheological properties. As nowadays all modern inks are a little changed in terms of ISO 12647-2 dot gain requirements and they are now more sensitive to the very exact ink/water regulations. If looking in the very idle printing element we can consider it as a figure filled with ink-water emulsion. The water-ink flow can be described with the Ostrogradsky-Gauss formulae: ׮ ν ሺ νሻ Ԧݔݕݖ ൌ ׭ ሺ Ԧ ሺΩሻ ߗ ሬ Ԧ ሻ . A divergence parameter shows the flow density in the field ν which is limited by Ω1 and Ω2 surfaces on the continuously-differentiated vector-function Ԧ which should be determinative in this very point of the field. In terms of vector field flow we can explain the ink/water emulsion transfer from the printing plate to the blanket and afterwards to the imprint using also the theory of mathematical delays concerning the instability of regulations feedback. Therefore we can predict the outcome for ink emulsification in the very exact point in the printing plate and in general also.