Research And Analyse Of Halftone Screen-Printing Processing Parameter

The research targets are to study the internal relations of mainly processing parameter deeply, and to provide base theory for the selection of mesh count and implementation datamation and standardization. The parameter defining of halftone-screen is one of important subjects in screen-printing proceeding and directly influences the printing quantity, printing cost and economic performance of printing company.The main research methods are:(l) theory analysis: analyzing the reproduction law of smallest dot size based on graphing method and dot producing theory; controlling ink deposit of printing product, according to the ink transfer theory and ink volume of screen printing combining with experiment; studying printing moire phenomenon by the basic theory of geometrical optics and Fourier optics, bonding the principle of space visual compounding. (2) Experiments research: the reappearance of dot is verified by printing gray scale to get the specimen sheet and measure the value of specimen sheet by reflection density apparatus(X-Rite 428); the specimen sheets are obtained by experiments and measured by hand held micrometer, the theoretical ink volume is gained by calculation; the effect of ratio of mesh count to screen ruling to moire is verified by printing grey scale (screenruling: 307/cm) through using different mesh count to study moire; (3) Data processing: means of average value is used in processing data and error causes are explained.The main work are: (1) the analyses of theory are finished for defining mesh count, the formula of calculating min thread diameter is deduced;(2) mathematical model has been deduced about the relation of ink film thickness with theoretical ink volume; (3) angles rational disposition of film separations are verified, the rational range of ratio of mesh to line are defined.The main conclusions are: (1) the thread diameter of mesh for reappearing smallest dot can be calculated directly by screen ruling and printed tonal value; (2) the results of experiments and calculation have been shown that ink film thickness of printing products can be controlled efficiently, the relative error is about 4%, improving the quality of printing products apparently;(3) experiments results have been shown that moire can be decreased apparently according to the selected ratio of mesh count to screen ruling under traditional screen ruling.