Experience of Prepress Output Quality Management (4)

Output film quality

The inspection of the output film quality, as the last process of filming, should really play a role in remedying plugging and plugging, so we should pay enough attention to it.

1. Check the fitting accuracy. In general, the coupling error of continuous output four- or multi-color film is very small, if one job needs to fill in one color or two colors, and the other color film is one day, two days or longer Output, at this time should carefully check the color film of the matching accuracy, if the fitting error is large, you should continuously output all color version of the film. Of course, this should be based on the use of the image-setter, the stability of the work, and some photosetters even if four-color film continuous assembly error is very large, then you should consider the maintenance or update the machine.

2. Check the imprinting relationship of each color version against the original or proof. Occasionally, layout elements may be lost or misplaced due to personnel operations or machine failures. For books and magazines, the best way to check is to attach the film to the original or proof, and if it is wrong, it will be clearly visible. Of course, in this process, care must be taken to avoid scratches on the film and affect the quality of the print.

3. Check if the film is dirty. Dirty film is a common problem in the output process. Generally speaking, the washing tank should be cleaned before starting the machine every day. Before the water injection, the water purification equipment of the external water supply switch should be turned on to prevent sediment deposited in the pipeline from being carried into the washing tank, scratching or adhering to the film. Film quality. After the work is finished, empty the washing tank and carefully clean it.

4. Check the screen angle of the colored output film. In order to avoid hitting the net, in theory, there should be a difference of 22.5° between the four colors, and in practical production, four-color printing uses 15°, 45°, 75° and 90° more. The yellow version has weak visual stimuli and poor visual perception, so it is generally set to 90°. Because human vision is most sensitive to 45°, the main color version of the original is generally set to 45°. The specific settings should be based on the design of the printed product. The angle of the cable can be checked through the magnifying glass on the angle of the screen of each color version of the film, or can be measured using the cable angle measurement tool. In addition to customer special requirements, the general network cable angle setting should not be arbitrarily changed to avoid unnecessary losses.

5. Check the on-site density of the output film. Through the transmission densitometer to check the density of the film on the ground, it is generally required to be above 3.5, preferably around 4.2. If the density is too high, the phenomenon of stencil printing will occur. If the density is too low, the ink will be subdued and unrealistic for printed materials with text and on-site layout. At this time, it is necessary to consider replacing the fixing solution or cleaning the laser head to ensure the stability of the output film quality.

In summary, the pre-press output process is carefully and accurately checked, and corresponding measures are taken to control it. This can not only improve the quality of photostrips, but also improve the production efficiency.