Determination of the Ink Layer Thickness, Taking into Account the Surface Roughness of the Printing Forum

Abstract

In the article, the influence of the surface roughness of the printing plate on the thickness of the ink layer on the surfaces of the cylinders of the printing apparatus during ink transfer was studied. An analysis was made of the works devoted to the contact of the cylinders of the printing apparatus, as well as to the ink transfer and division of the ink layer. The influence of the surface roughness of the printing plate on the thickness of the ink layer, which ensures the quality of prints, has been established. A technique has been developed for determining the thickness of the ink layer, consisting of two stages, taking into account the roughness of the surface of the printing plate. At the first stage, the thickness of the ink layer on the printing plate after rolling, but before contact, was determined, and at the second stage, the thickness of the ink layer was determined on the offset blanket (deckle) after contact between the plate and offset cylinders. The thickness of the ink layer on the surfaces of the cylinders of the printing apparatus was estimated by the gravimetric-weight method. To estimate the amount of ink, the printing plate was weighed three times - before applying ink, after applying ink - before contact and after contact with the deckle. The difference in weights made it possible to have an idea of the mass of paint on the surfaces of the cylinders. On the basis of the experimental results obtained by the proposed method, the values of the thickness of the ink layers on the plate (on the form) and on the offset cylinders (on the deckle) were determined, taking into account the surface roughness of the printing plate. It has been established that at high roughness values, the amount of paint increases, which increases the thickness of the ink layer. The obtained results of the thickness of the ink layer on the deckle make it possible to determine the technologically necessary thickness of the ink layer on the print, which is the main factor for ensuring print quality. Taking into account the values of the surface roughness of the printing plate, it is possible to determine the technologically necessary pressure in the contact zone of the cylinders, which is an important factor for ensuring the technologically necessary thickness of the ink layer on the print. The results of the studies show that the data obtained are significantly different from the results of similar studies on the division of the ink layer between the cylinders of the printing apparatus and are more accurate, which is important for setting up the printing machine and ensuring the quality of prints.