Web tension profile and gravure press runnability - The benefits of on-line tension profiles are discussed

An on-line web tension measuring device has been installed on a rotogravure press in a Finnish printing plant. The device provides both web direction and cross web direction measurement of unwinding paper rolls. Thr tension p rofiles of over 5500 rolls of LWC and SC paper were measured. The effects o f web tension variability on press runnability and waste were documented. F or good runnability and low wastage on the press, roll tension variability within a roll and from roll to roll should be within certain margins. The s tudy also related tension profile development in the paper mill to the pres s room performance. It was found that the tension profiles on the printing press were inherited from the paper mill, either from the paper machine or the supercalenders. While the printing plant can accommodate certain roll t o roll variability by sorting the rolls and running them in sequence, the p roblem of tension uniformity must be fixed in the paper mill. The means of control on the paper machine or on supercalenders are discussed.