Introducing the basic process of screen printing mesh today(1)
Screen printing mesh consists of a screen printing screen, a squeegee, an ink, a screen printing machine and a substrate.
The principle of screen printing is to use the basic principle of the screen printing part of the screen printing screen to penetrate the ink, and the non-image part of the mesh is not transparent.
When printing, the ink is poured on the screen printing screen, and a certain pressure is applied to the ink portion on the screen printing screen by the squeegee (scraper) while the other end moves, and the ink is scraped from the mesh of the graphic part during the movement. Squeeze onto the substrate.
The process flow is basically as follows:
1. Plate making--Make screen printing screen according to the pattern to be printed, and make it by film, choose mesh, pull net, clean screen, sizing, exposure.
2. According to the material, select the appropriate ink and the hardness of the squeegee.
3. Adjust the screen printing machine, proofing test (ink color, ink effect, ink firmness)
4. Mass production.
1. the choice of plate film
To get a rich layer of screen prints, first make a film like offset printing, use 100 ~ 133 lines / inch of dot output, too high line number is not conducive to the reproduction of the low-key level. If a circular dot is selected, since the screen printing dot reproduction curve is reduced below 20%, 70% of the dot is enlarged, and the tone curve adjustment is performed on the image before the film is taken out. Generally, the screening angle of the film is: magenta plate 15°, cyan plate 75°, yellow plate 90°, black plate 45°, and practice has proved that there are very few overprinting moiré. In addition, in order to ensure accurate overprinting, even if it is a line draft, it is not necessary to use sulfuric acid paper negatives. If you don't have a prepress production department, don't ask the advertising banner production company to make the printing film, because they have a low number of film lines and the level is lost, which will affect the printing clarity.
2.the choice of wire mesh
High-mesh yellow plain woven polyester mesh is a necessary condition for high-precision screen printing. The yellow color is to reduce the diffuse reflection of the exposure light when printing, and the flat woven mesh can form a thin screen to facilitate high-level, low-key reproduction. The same mesh number of mesh has a variety of wire diameters to choose from, it should be easy to break the net. The ratio of the mesh number to the number of film screen lines is 3.5:1. If the number of screen lines is 120 lines/inch, the screen should be 420 mesh.
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