Thermal changes in a Waterless Sheet-Fed Offset Inking Station, 2000 International Printing & Graphic Arts Conference Proceedings

Jan-Erik P. Nordström--Heat build-up was studied in a sheet-fed waterless offset press run without ink or substrate at a maximum speed of 15 000 impressions/hour (approx. 3 m/s on a 52x74 cm, or 20x28", press) and initially without using cooling. In the second step, cooling efficiency was determined in the press equipped with three temperature-controlling rollers within each inking unit. Ink and substrate were finally added with a specific lay-out to find out whether ink transfer had an effect on heat transfer from the inking station, and to find out when temperature-related process stability was reached.

Oscillating rollers induced the heat build-up in the inking station within a time-scale of minutes. The sheet-fed offset press bearers were the second major source of heat build-up within a time scale of hours. Ink transfer at high plate coverage (50% of total plate-cylinder printable area) was found to remove very little heat from the press, and only a slight temperature rise was seen on the printing plate image areas transferring ink during a production-related print run. Blanket temperature was affected only by heat created within the bearers. Details are discussed and suggestions for development are included.