(1) Separation film. The color separation film directly affects the quality of the plate and the printing effect. Since the flexographic printing uses an anilox roller, the anilox roller meshes are arranged at an angle (currently 60° or 45°). In order to avoid the occurrence of moiré, the screen angle of the flexographic film is 7.5 compared with the offset printing. The difference between °. If the film is made with a flat exposure mechanism, the image should be compressed according to the diameter of the plate cylinder, the thickness of the double-sided tape, and the thickness of the plate before film production. Attention should also be paid to the matching of film and plate graphic performance. The use of frosted negatives will be more conducive to the production of plates.
(2) Plate material and production. First, the corresponding plate should be selected according to the type of ink used. Not all plates are suitable for UV ink. The wrong selection will cause the plate to expand and deform during the printing process. The plate making process is also very important, and the time control of each step should be just right. Underexposure, over-adhesion, insufficient drying, and improper storage will reduce the life of the plate.
(3) Anilox roller characteristics. First, the choice of anilox roller should follow the following principle: the number of screen lines (line/inch or line/meter) of the color separation film should be at least 1:3.5 compared with the number of lines of the anilox roller, and the dot printing should be 1:5. The ratio. The degree of cleaning of the anilox roller is also very important. Regular and thorough cleaning of the anilox roller ensures ink transfer, ink color matching and repeatability.
(4) Ink type and compatibility, ink system. Different substrates should be used with corresponding inks, such as paper ink, PE, PP, PVC, PET and other plastic film inks, aluminum foil materials and so on. Inaccurate selection of the ink system, or poor ink compatibility, may result in a decrease in the adhesion and strength of the ink on the surface of the substrate, and may even cause a chemical reaction. The color of the ink directly affects the color quality of the print. Especially for the spot color ink, it is usually firstly modulated in the ink chamber and detected by a colorimeter. Now the professional supplier's chroma density meter function is more complete. The instrument can give the recommended ink color matching formula according to the ink database provided by the ink manufacturer, which greatly improves the working efficiency.
(5) Printing machine and its operation and adjustment. This factor clearly determines the quality of the print. The ink stick caused by the gear backlash in flexographic printing is affected by the defects of the printing press itself. The tension control capability and manufacturing accuracy of the printing press also affect registration and printing accuracy.
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