The most basic requirement for multicolor prints is accurate registration. The accuracy of overprinting is one of the most important factors affecting product quality. Generally speaking, overprinting is inaccurate, referring to three situations: First, the size of the graphic text is deformed, especially the longitudinal dimension shows the phenomenon of elongation and shortening; second, the overprinting between one color and another color is inaccurate; And there are. To solve these problems, we must always implement the following eight words throughout the printing process: "At all times, we need to defend everything." At the same time, the following four aspects of the process must also be properly addressed. 
First, strive for the consistency of the linear velocity of the three rollers.
The operator must first realize that it is difficult for the three rollers of the plate cylinder, the blanket cylinder, and the impression cylinder to reach the same speed of the curve during the movement. Not only the lining thickness will greatly affect the speed change of the drum line, but also more difficult to control is that the elasticity of the blanket is different, and the deformation due to the pressure difference is different, so that the linear speed of the drum is changed, resulting in deformation of the longitudinal pattern of the printed sheet. . 
In order to achieve accurate registration of printed matter, it is necessary to make the three rollers have the same linear velocity during movement. To achieve this, it is necessary to strictly control the thickness of the lining, and also to take measures to deal with the deformation of the blanket due to pressure. We have conducted surveys in some factories and found that some operators have far less stringent control over the thickness of the drum lining. The data stipulated by the equipment are mostly ±10C, and some are even larger. The more noteworthy issue is that every change in the thickness of a printed sheet is caused by a different flight frequency on one machine, each applying its own method, causing a greater error in the thickness of the lining. Therefore, from the perspective of business management, we must first clearly indicate the data of the lining thickness of each machine, and check regularly to ensure that the data is accurate. When there is a change in the thickness of the printed sheets, correct and unified processing methods are required. 
Another problem that is worthy of attention by operators is that the plate cylinder and the blanket cylinder affect the longitudinal dimension of the picture. If the diameter of the plate cylinder is equal to the diameter of the blanket cylinder after lining, the longitudinal size of the footprint of the footprint must be greater than the longitudinal size of the plate footprint. To make the longitudinal size of the imprint footprint equal to the longitudinal dimension of the plate imprint, thicken the plate cylinder liner 0.1mm (about the thickness of a 100G bond paper), the two will be equal, the longitudinal size of the imprint imprint will be accurate The ground is reproduced on the printed sheets. 
Second, must be constant cut paper and offset printing workshop temperature and humidity Temperature and humidity changes will seriously affect the expansion and contraction of the paper, which is understood by the peer. Printing enterprises in Guangdong have not attracted enough attention in this issue. The performance is: only the temperature control, no relative humidity control; some plants have constant temperature equipment, but no one management, temperature and humidity are not constant, only to seek operator comfort, did not take into account product requirements, some plants only offset printing workshop, ignore the cut paper Workshops and white paper, semi-finished products stacking workshop; some plants subject to conditions, there is no equipment for temperature adjustment and humidity control; a considerable number of plants lack strict management measures for paper and semi-finished products. 
The experience of domestic printing companies is that offset printing workshops, paper cutting workshops, and white paper and semi-finished product stacking workshops should all have a constant temperature and humidity, and should be controlled within a range of 23°C±1°C and 63%±3% relative humidity. Should assign someone to manage it every day and do its utmost to keep every corner of the shop within this range. Lack of adequate input and control management results in serious consequences. 
Third, meticulously do a good job before printing, printing process and post-press processing
There are two points in the printing industry that must be kept in mind: Among the many factors that affect the quality of prints, the quality of paper is the number one factor. Even papers with excellent quality have their own characteristics of deformation as the temperature and humidity of the environment change. (To be continued)