Products printed by screen printing machines are all within the scope of screen printing. The core quality parameters of screen printing include ink preparation, screen selection, doctor blade selection, screen positioning and screen printing process. What are the core technology and quality parameters of screen printing? Today I will introduce to you by Xiaobian:

一 、 Screen printing ink mixing

Method for judging the thickness and thinning of ink: After the ink passes through the screen, the printing surface should be free of screen or drawing as much as possible. If it is placed on the screen, the thinner is better. The ink can pass through the screen by its own weight. But not dripping. As printed lines get thinner, they should get thinner, otherwise they should get thicker.

Two, screen printing screen selection

The silk cloth on the screen printing screen is stable in quality, the wire diameter is uniform, and the mesh number is accurate and consistent. The commonly used mesh is 450 ~ 500 mesh. For printing materials with fine lines, high ink fineness, and poor absorption, the mesh number should be high. Screen; instead, you should choose a screen with a low mesh count.

The position and size of graphics and text on the screen during plate making shall be determined according to the structure and size of the substrate and the position of graphics and text on the substrate. If the design is not good, it will affect the quality of screen printing and even hinder screen printing. In addition, use the screen to print pictures and text on the same print. If it is divided into two or more screen printing processes, the qualified rate of screen printing will decrease.

III. Screen printing scraper

The blade used in screen printing is mainly made of polyurethane. The polyurethane rubber blade has good abrasion resistance, solvent resistance and resilience. Its hardness is 60-80 Shore hardness. For printing materials with high screen tension and good surface flatness, a high-hardness scraper should be used. Instead, choose a low hardness. When printing on curved, low-spherical or poorly flat (partially protruding) substrates, the blade width should be narrower than wide.

Fourth, screen printing screen positioning

的 The fixture materials used for screen printing include metal, wood, plywood and transparent PVC sheets. If positioning is difficult and the size of the printed material is small, a metal clamp should be selected. If the picture and text are closer to the edge of the substrate, a flat piece of wood as high as the edge of the substrate should be fixed next to the substrate to avoid the pictures and text being easily pasted. The clear distance is generally 1.0 ~ 2.5mm. If the printed pattern is easy to paste or has texture, the texture distance should be adjusted.

V. Screen Printing Process

If the scraping pressure is high during screen printing, the ink output will be large, but the screen plate is easily deformed, so the scraping pressure should not be high. The scraping speed is usually 60 ~ 200mm / s. The scraping speed is fast and the ink output is small, but it is not easy to block the screen. Therefore, screen blocking ink should scrape faster.

There are straight lines, oblique lines, and curves for the scratch line. They should be selected according to the flatness of the substrate and the distribution of graphics and characters on the substrate. Layer the ink, and then scrape the ink.