Details:
Summary:
The main purposes of this experimental study were to (1) identify the most important factors that influence dot gain of CD-ROM decoration using the UV waterless offset press, and (2) establish optimum process operating conditions so that the minimum yield of dot gain and maximum yield of print contrast could be obtained. The experiment was conducted using a randomized 23 factorial design on a waterless offset press using UV inks at a major CD manufacturing and printing plant in Taiwan. A total of 800 printed discs were gathered and 50 of them were systematically sampled for each of the eight treatment combinations for a total sample size of 400 (8*50). Overall the results suggested that the interaction effect of the blanket-to-disc pressure and cooling system temperature was the dominant variable affecting on-press dot gain and print contrast. The interaction effect was found to be a significant variable to almost all observations. The study also found that the greatest print contrast and least dot gain could be achieved when the blanket-to-disc pressure was established at 2.95mm and the cooling system temperature was set at 17 oC on the press, while controlling for all other variables. To obtain the widest tonal range in shadows, the press operating condition should be established as: press speed = 50discs/min, blanket-to-disc pressure = 2.95mm, and temperature of the cooling system = 17 oC, while controlling for all other variables.