Cylinder Gap Shock and its Impact on Quality of Prints in Offset Printing Technique

There are many factors in offset printing technique, which determine the final quality of the printouts. Next to ink, dampening liquid and paper properties, significant role plays here construction of printing unit and its technical condition. Many works, where problem of vibrations was investigated, point canals in plate and blanket cylinders as source of vibrational excitation in printing unit. The canals may generate vibrations of inking and dampening rollers, as well cylinders themselves. If wear of bearings, looseness and unbalance of rotating cylinders and rollers will be additionally taken into account, there may be expected, that excited vibrations will seriously influence on the results obtained during printing process. Some undesired artifacts, for instance, cross stripes may be noticeable on the prints then. The main scope of the researches presented in this paper was to find relation between vibrations in offset printing unit and their influence on quality of the printed image. For this purpose, while printing, measurements of vibrations of printing unit have been made. Afterwards printed test image have been precisely analyzed in search of undesired phenomena, which can be an effect of excessive vibrations in printing unit. Then comparison between position of the artifacts on the prints and the results of vibration measurements has been made. Effects of the experiment are presented in this paper.