1. Ink blending
When printing on an open type rotary screen printer, the method for judging the degree of ink density adjustment is as follows: The degree of density is based on the fact that the ink does not appear on the printing surface after the ink passes through the screen. The dilute degree is best placed on the screen, the ink can reach through the mesh by its weight but not drip. When the printed lines are thin, the dots should be thinner, otherwise, the dots should be thicker.
2. Screen selection
When printing on an open type rotary screen printer, the quality of the screen cloth is uniform in diameter and the number of meshes is accurate and consistent, which is stable quality. The generally selected mesh is 450~500. For substrates with fine lines, high ink fineness, and poor absorption, a screen with a high mesh number should be used, otherwise, a screen with a low mesh number should be used. The position and size of the graphics and text on the screen during plate making should be determined according to the structure and size of the substrate and the location of the graphics and text on the substrate. If the design is not good, it will affect the quality of the screen printing, or even fail to screen. Also, the pictures and texts on the same thing to be printed should preferably be printed by a screen. If it is divided into two or more screen printing, the process will reduce the silkscreen pass rate.
3. Squeegee selection
When printing on an open type rotary screen printer, the squeegee is mostly polyurethane. The polyurethane rubber scraper has good abrasion resistance, solvent resistance, and resilience. The hardness is 60~80 Shore. For the substrate with high screen tension and good surface flatness, a squeegee with high hardness should be used. On the contrary, low hardness should be used. When printing on a curved surface, a low-degree spherical surface, or a substrate with poor flatness (partially convex), the squeegee width should be narrow rather than wide.
4. Screen positioning
The fixture materials used in general factories are metal, wood, plywood, PVC transparent sheet, and so on. If positioning is difficult and the size of the substrate is small, metal fixtures should be used. If the picture and text are closer to the edge of the substrate, a flat piece of wood that is as high as the edge of the substrate should be fixed next to the substrate to prevent the image and text from being easily blurred. The distance between the screen and the substrate is generally 1.0~2.5mm. If the printing pattern is still easy to paste or there are nets, you should increase the distance between the screen and the substrate.
5. Silkscreen process
If the squeegee pressure is large, the ink output will be large, but the screen is easy to deform, so the squeegee pressure should not be too large. The scraping speed is usually 60~200mm/s. The printing speed is fast and the ink output is small, but it is not easy to block the network. Therefore, the ink that is easy to block the net, the scraping speed should be faster. There are three types of squeegee routes: straight, oblique, and curved. It should be selected according to the flatness of the substrate and the distribution of graphics and text on the substrate. When the squeegee line is long and the ink consumption is large, the amount of squeegee should be more, even if the ink is applied first, then the ink is squeezed.