Close the good printing process and operation technology (2)

Second, the size of the printing plate surface deformation

The deformation of the flexographic layout is an inevitable phenomenon. This is because the flexographic printing press is a high-speed rotary press. The radius of the printing roller is small, so the bending deformation of the printing plate is large. After the printing plate is pasted on the surface of the cylindrical roller, the printing plate is along the circumference of the roller. The surface of the bending deformation, so that the print image size changes are more obvious. In addition, the characteristics of the web printing material are soft, and the stretching change easily occurs under the action of the tension and the printing pressure during printing, so that the substrate in the axial direction of the cylinder has a shrinkage phenomenon. In addition, the flexographic print graphic part is convex structure, and the non-text area is concave, so that if the printing speed is adjusted lower, the printing pressure is adjusted, the precision of the machine is lower, and the blank layout area is larger. The greater the relief depth of the graphic and text, the more distortion occurs in the printing layout. Variations in the specifications of the printing plate graphic text make the printed semi-finished products not meet the requirements of the process design. This has a great influence on the print products with higher quality requirements, such as inaccurate overprinting. After the semi-finished products have been die-cut, slit, or trimmed into single-structured products, deviations from the layout of printed graphics and texts occur, especially the printed layouts of multi-imprinted structures. This phenomenon is particularly severe, and the finished products often fail to meet quality standards. Or process design requirements. In view of the above-mentioned quality defects, it is necessary to take measures to overcome the changes in the printing size. Firstly, the printing plate should be flattened, and the contact between the printing plate and the roller should be tight. When the printing plate is glued, it must be aligned at one time to prevent the plate from being deformed. Secondly, the printing pressure should be properly controlled and the pressure must not be too great. The third is to control the tension when the roll material is conveyed. There should be no looseness or tightness. Fourth, the printing speed should not be too fast or too slow, and the printing speed should be kept constant. Fifth, it is necessary to pay attention to the maintenance of the machine and do a good job. The lubrication of components prevents the wear of critical components and affects the printing accuracy. Sixth, according to the usual accumulated production experience, the layout specifications are properly adjusted during the plate making process so that the distorted layout after printing meets the quality requirements for overprinting, die cutting and trimming. .