Thermal Balance of a Sheet Fed Offset Press and its Effect on Ink Transfer

The temperature of ink has a significant effect on its physical properties and hence the ink transfer in the printing process. In order to increase the thermal stability of a printing press it is necessary to obtain an understanding of how the various sources of heat interact in the process. This paper reports on a study of the temperature variations at various locations in and around a production four-colour sheet fed offset press. The press was fully instrumented to obtain frame and ink temperatures, with infra red measurement system used to measure temperatures on the rolls. Large local time dependent temperature variations were found throughout the press. These changes were related to colour changes on the printed product. A thermal balance was made on the generation and dissipation of heat. This highlighted ways in which the press thermal stability could be improved.