In the packaging and printing industry, a variety of flat color screen printing are often needed. Today, China paper network editor found the relevant content and introduced the operation skills in detail.Operation method of plane color screen printing.
1. Selection of plate making film.
In order to obtain screen prints with rich levels, first make films like offset plates, and select the website output of 100-133 lines / inch. Too high number of lines is not conducive to the reproduction of medium and low-key levels. When selecting the circular website, the copy curve of the screen printing website is reduced below 20%, and 70% of the website becomes larger.
The step curve of the image must be adjusted before publishing. The network angles of general films are magenta version 15 °, green version 75 °, yellow version 90 ° and black version 45 °. Practice has proved that moire rarely occurs.
In addition, in order to ensure the correctness of the jacket in the later stage, the negative of sulfuric acid paper shall not be used as far as possible even for the network printing of line draft. If you don’t have a pre printing production department, don’t entrust an advertising banner production company to produce tanning film. The number of film lines they produce is low and the level is lost, which affects the clarity of printing.
2. Selection of wire mesh.
High mesh yellow plain woven polyester screen is a necessary condition for high-precision screen printing plate. Yellow is to reduce the diffuse reflection of exposure light when printing;
Flat woven mesh can form a thin screen, which is convenient for high-profile and low-key reproduction. The same mesh of wire mesh has a variety of wire diameters to choose from, so it should not be easy to break the mesh. The ratio between the number of wire mesh and the number of wire mesh of the film is 3.5:1. If the number of wire mesh is 120 Wires / inch, 420 mesh wire mesh shall be selected.Operation method of plane color screen printing.
3. Pull the net.
The use of large face mechanical stretching machine can obtain large tension, prevent tension relaxation in printing and prevent screen deformation. The same screen with the same screen tension can be stretched obliquely. The warp and weft line of the screen cloth is at an angle of 22.5 ° with the screen frame, which helps to reduce the shortage of mesh points and make small words and lines perfect.
When stretching the screen, the initial tension should be large. After that, pull the screen every 1 hour. After 12 hours, measure the screen tension with a tensiometer.
The tension difference of each part is required to be no more than 1n / cm (the tension after screen sticking printing is 24-25n / cm). In addition, aluminum alloy or steel grid frame shall be selected, and the wooden frame is easy to deform after immersion in water.