General Analysis of Web Tension Conditions in an Offset Press with Practical Test Methods and Results

A mathematical description of factors that determine print repeat lengths. The analysis is based on non-slip conditions in the impression slip. The analysis explains why tension variations can move up stream through the press even when non-slip conditions exist. Practical test methods to determine parameters that characterize the effect of the blanket will be shown. Methods for plotting the operation envelope and range of the press relative to print repeat length will be demonstrated. Methods for calculating tension between print units will be presented. This work was done to understand the requirements for insetting (printing in register on pre-printed material). Insetting topics will be discussed. Related print register and print length topics will also be referred to.