Testing and Research on Inking Properties of Offset Press

Abstract

A new testing form was designed, in which the screens having gray scales and some solid blocks were included. The screens consist of gray scales from 0 to 100% of dot coverage, and the solid blocks also have coverage scales from 0 to 100%. Printing experiment was performed, and densities and dot coverage of specific places were measured and recorded. Based on the testing data, density or dot coverage undulation with printing impressions was indicated by curves. Furthermore analysis was taken. Dot gains in the same prints are not constant, which cause that saddle shape in prints. Some reasons from construction of press such as the gap of cylinder, swing of transferring roller and oscillation of oscillating rollers were brought out. Same values of ink presetting can not get the same printing quality in the ink zones which have the same graphic coverage. The traditional press has a long make-ready time in printing running, which can reduce the efficiency of press. Shaft-less technology of inking system is put forward to cut down the make-ready time and to decrease the power consumption. New algorithm research is necessary for ink zone presetting in order to get more precise ink feeding. Some research on the press construction is also important for the press having some inherent defects