Details:
Summary:
As part of a programme aimed at improving the colour control in heat set web offset printing, the effects of process parameters on ink transfer using an eight unit press were investigated. The press was fully instrumented for the measurement of temperatures, roll speeds and web tension. After through the run monitoring exercises to establish the range of colour variations using a spectrophotometer and the optimum sample size measurement. The effects of some of the press operating conditions were evaluated by a series of orthogonal array experiments designed using the Taguchi method. Orthogonal array experiments allow the simultaneous variation of several parameters, thus minimising the size of the experiment while still being able to analyse for the effect of each independently. The experiments were performed during normal production and analysis of the test strip was carried out using spectrophotometry with customised software. This allowed the effects of experiments to be assessed without a serious disruption of production. The experiments highlighted several key parameters whose control is vital to the stability of the ink transfer process. The font parameters varied showed no measurable effect.