What is the effect of screen pitch on book printing registration?

What is the effect of screen pitch on book printing registration?

In multi-color printing and four-color screen printing, registration must be achieved of book printing. The screen pitch plays a vital role in stable printing registration. It can be understood from the definition that non-contact printing cannot produce a true 1:1 reproduction of the original image. This is because the deformation and elasticity of the screen cause the image displacement on the printing material during the printing operation. In order to minimize deformation as much as possible, the lowest possible mesh distance should be used.

When the net distance increases, the following two situations will occur:

(1)The squeegee pressure must be gradually increased until the screen printing plate is in contact with the printing material in order to achieve ink transfer. The extra force exerted on the screen printing plate will be amplified at both ends of the squeegee. Relative to the screen frame size, the longer the squeegee, the more serious this effect will be. As a result, not only is the image on the edge deformed, but the printing quality is also poor.

(2) The entire image becomes more and more oblique and longer, partly because of the influence of the screen pitch, but it also varies with the image positioning, the length of the squeegee and the direction of the squeegee. There are no specific regulations on the irregularities of these positioning and dimensions, and it is more difficult to predict and manage. The shrinkage and expansion of the printing material is also the main reason for this problem.
Inconsistent screen spacing is also a problem. If the screen spacing from front to back or from one side to the other is different, local areas will be inaccurate. In this case, no matter what you do, the next color will be printed with It is impossible to register the first color. If the registration problem is serious, the entire printed matter will be scrapped.

It is worth mentioning that some distortions can be calculated in the original production to compensate, which is usually done in electronic printing. In addition, some Chinese printers provide optional parts on certain types of printing presses to compensate and deal with this problem.

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