Baglay V. Technological ensuring of intaglio printing plates quality

The dissertation work is devoted to solving an actual scientific and applied task – developing technological quality assurance of intaglio printing plates produced by direct laser engraving and applying a protective nitride-chromium coating by vacuum sputtering. Intaglio printing (metallographic printing) is a highly secured type of gravure printing used worldwide to protect mainly banknote products, which is mandatory according to the recommendations of Interpol. Measures to improve the quality of intaglio printing also demand improving the quality of plates. The most modern method of manufacturing intaglio printing plates is direct laser engraving technology which has a number of advantages and technological possibilities compared to traditional etching technology. However, the peculiarities of processing the materials of the plates with a laser and the subsequent application of a protective chromium nitride coating by vacuum sputtering (PVD) can cause a decrease in the plates' durability compared to traditional technologies of plate making. Therefore, the technology of direct laser engraving with vacuum sputtering of a protective nitride-chromium PVD coating needs improvement. Research aimed at improving the quality of intaglio printing plates is an urgent scientific and applied task. The solving of this will contribute to the increasing of state security in the field of banknote production. The dissertation work was carried out within the framework of research work No. 2212-p, state registration No. 0119U100984 "Theoretical and practical principles of ensuring the quality of metallographic printing". The aim of the dissertation is to develop technological quality assurance of intaglio printing plates made by the method of direct laser engraving and vacuum sputtering of a protective coating. To achieve the set goal in the work, the main content of which is laid out in four sections, a number of tasks were completed. In Chapter 1 "Ensuring the quality of intaglio printing in the modern banknote production", the detailed comparative analysis of the technological processes of manufacturing intaglio printing plates is carried out from the point of view of ensuring the quality of the plates and in the context of the environmental safety of their production. The model for determining the environmental efficiency of intaglio printing plate production was developed. The analysis of the technological features of intaglio printing, which cause the deterioration of plates, was carried out, and the system for forming the run length durability of intaglio printing plates was developed. The tasks of the dissertation research have been formulated. In Chapter 2 "Research materials and methods", a general algorithm for conducting research on improving the quality of intaglio printing plates has been developed. The materials, equipment, and methods have been chosen. The new methods of researching the quality of engraved strokes have been developed for the entire complex of experimental and theoretical research. In Chapter 3 "Investigation of the state of the surface and surface layers of printing and blank spaces, run-length resistance and printing quality of intaglio printing plates made by direct laser engraving with vacuum sputtering of a protective coating", it was presented the results of research on changes in the state of the surface and near-surface layers of engraved strokes, run length durability, and printing quality of intaglio printing plates made by direct laser engraving with sputtered of a protective coating. The processes and all types of influences in the printing section of intaglio printing machines were analyzed. The wear mechanisms in the printing section of the intaglio printing machine were established. The integrated model of wear of intaglio printing plates has been developed. In Chapter 4 "Improved technological process of intaglio printing plates making", the influence of manufacturing technological parameters on the quality parameters of engraved printing elements and generalized indicators of the quality of engraved strokes of plates made by direct laser engraving are determined, the means of ensuring the quality of intaglio printing plates are determined, the quality parameters of model plates made by alternative technologies are investigated, and on this basis, the system of technological assurance of the quality of intaglio printing plates has been created. A number of obtained experimental results regarding the relationship between the parameters of engraved strokes and modes of plate making have been described. The integral coefficient of engraving quality and the complex indicator of the quality of plates have been formulated. It has been proved that the state of the surface of strokes is another additional factor in ensuring the wear resistance of plates.