The printing speed of the offset press has an effect on printing pressure and imprint fastness. Many examples show that when the printing speed increases greatly, the printing pressure will also increase. This is because, with the increase of printing speed, the contact time of the corresponding points between the plate and blanket will be reduced correspondingly. This reduction of time means that the degree of incomplete contact between printing surfaces increases, which is very dangerous. In order to effectively avoid the incomplete transfer of pictures and texts caused by the incomplete contact between the printing surfaces, the screen sticking is not solid, the ink color is light, and the imprinting ink color is not fixed firmly, it is necessary to use a larger printing pressure. In this way, the ink can be quickly transferred from the ink supply surface to the ink-receiving surface, and the ink can complete its ideal graphic transfer process in a short time.
At present, the speed of offset press is increasing rapidly. The maximum printing speed is 15000 sheets/hour. When the speed of the machine is high, the printing pressure must be correspondingly increased
1. To increase the printing pressure can not make up for the short time caused by the imprint is not solid, empty disadvantages, in order to improve the firmness of the imprint.
2. With the increase of machine speed, the radius of the drum will decrease with the increase of the drum utilization coefficient. If the diameter of the cylinder is small, the compression width in the rolling process will be reduced accordingly. If the printing pressure is not increased, the transfer of ink will also be affected.