Summarizing the Quality Inspection Standards for Printing Films

The film's output is actually a camera-like exposure process. It first processes the graphic image through a RIP-processed dot-matrix image (that is, a web of dots) and then converts it into a signal that dominates the laser. The laser-relative film is used. The vertical and horizontal movements of the laser spot (ie, dot) are shot (shot) to the corresponding position of the film, so that the corresponding part of the film is exposed, and then the unfixed part is washed out by the developing process of the developing machine. Films form bitmaps on the film.

As for the quality standards of the film, it should mainly include the following four aspects:

First, the density of the field and fog, it is the basis for measuring the quality of film. Fog refers to the absolute density of the blank film, ie, the density of blank film measured after the density meter is absolutely cleared (clear to air), the film with the fog value <= 0.03 is excellent, and the 0.03 to 0.07 is qualified. The so-called field density refers to the density of the Dashen block. Generally, the gray scale of the emission software is too small due to its small area, and some film films have trachoma, making the actual density measurement value smaller than the actual value. Generally, it is qualified between 3.5-3.8, but if there is a large field, it must ensure that its density value is between 4.0-4.3 to ensure the color saturation of the printed matter and does not make the darkness level gather.

Second, the linearized value, which is the main factor in the quality of the film. Generally, it should be ensured that the difference between the marked value on the film gray scale and the measured value is ≤2. However, since the general high-precision printers have a certain degree of color adjustment, we only need to ensure that the linearized difference ≤ 5 can guarantee the quality of prints.

Third, the shape of the outlets, the angle of the network, and the number of hanging lines. The outlets are required to be sleek, sturdy, without jaggies, and without tailing; the screen angle is in line with the standard (typically 45 degrees for single colors, 30 degrees for four colors), and does not impinge on the network; The number of suitable print media (such as: newsprint is not higher than 120lpi, coated paper is not less than 133lpi).

Fourth, the quality of the film after exposure is the last pass, and it is also the most easily overlooked factor. The film had no trachoma on the field, no scratches on the film, no traces of oil, and no “white spots” that had not been removed by the fixing. Can be said to be a quality film.

Hanging network accuracy

Hanging net accuracy is generally referred to as hanging nets. The higher the precision of the netting, the finer the printed products, but it has a greater relationship with paper and ink. If you print on a regular newsprint (newspaper) a picture with a high mesh size, the picture will not only become more exquisite, but will become a mess (miserable). Therefore, you must understand the printing of your printed matter before exporting. What is the use of paper, and then determine the accuracy of the net. General common paper and hanging mesh accuracy: imported coated paper or stickers, etc.: 175-200 lines; imported offset paper, etc.: 150-175 lines; ordinary offset paper, etc.: 133-150 lines; newsprint: 100-120 Lines, and so on, the poorer the quality of the paper, the lower the number of hanging nets, and vice versa.

Newsprint paper has a strong ability to absorb ink. The smaller the number of outlets, the greater the relative expansion. The 175 lines are smaller than the 150 lines, so the 175 dot enlargement is a bit severe. The same printing conditions, the printed color is a little deeper.

The high cable height does not mean that the quality of the product is high. Newsprint is best to use 150 lines! The shape of the outlets and the quality of their reproduction are an important criterion for determining whether a print is beautiful! Many foreign coated paper prints will also use 150 lines, the effect is as beautiful!

Printing dot angle

Blue: 15 degrees, Red: 75 degrees, Yellow: 90 degrees, Black: 45 degrees. The network layout of the general network is neat, so there will be an angle in the application. For example, in the case of monochrome printing, the angle of the screen is mostly 45 degrees. This is based on the dots printed on this angle, and is most comfortable to the eyes And it is not easy to notice the presence of outlets, which results in continuous graying.

As for printing with two or more colors, it is necessary to pay attention to the combination of the angles of the two nets, otherwise an unnecessary pattern will be created, which is called "Moier". Usually the difference between the angles of the two nets is 30 degrees, no net collision will occur, so the general two-color printing, the main color or dark color with 45 degrees, light color with 75 degrees, three colors are respectively 45 degrees, 75 degrees, 15 Degrees and other three angles, if it is the four-color printing, they are red with 75 degrees, yellow 90 degrees, green 15 degrees and black 45 degrees. There is no certain limit to these angles. They are changed according to different needs.