Printing Screening Process Talk - FM Networking (6)

26. Printing machine requirements

Two typical sizes of FM dots in high-quality jobs are 14 μm and 21 μm, and the printer must be able to pass these dots correctly to accurately reproduce all tones. The 14μm dot is approximately 1% dot size in a 200 line/inch screen. If the press can correctly pass 1% of the 250-line/inch screen, it will be able to print in the highest resolution in a random manner.

Because the finer dots in the highlights and shadows must be transmitted properly, the plate exposure is usually less than that of conventional screening. If the plate is not sufficiently exposed at the lower exposure setting, the micro dots will not last long on the printing plate, which requires post-exposure.

27. Printing machine registration

Because of the elimination of rose spots and moiré, the FM printing plate overprinting is not in time when there is no rainbow or color shift in the middle tone. However, inaccurately tuned FM screen images can still be seen, and still need to hide the slight substrate offset that may occur, especially on old or uncalibrated presses.

28. Printing preparation

Due to the unknown behavior of microdots in the water-ink balance interaction, the print preparation time is usually 25% to 50% longer than the conventional print preparation time. In the printing shop successfully using the FM network, it is said that it is easy to reach and maintain the ink-water balance.

29. Dot enlargement on printing presses

The secret of an excellent FM network is its excellent dot gain compensation curve. If compensation is used correctly in prepress preparation, no press adjustments are required. Any printer operation used to compensate for unbalanced screens will further result in color imbalance, turbid highlights, neutral neutral grays, and shadows that are inserted. Because the dot gain value is not easily changed by adjusting the ink film density, the color cannot be adjusted on the printing press. (This is a major advantage of the FM network: increase the ink density, get a larger tonal range, and it will not produce dot gains like the increase in ink density of the AM web.)

30. Ink consumption

Compared with the amplitude modulation network, the FM network consumes less ink. However, one of the biggest advantages of the FM network is the ability to transfer more ink without significantly increasing dot gain. As long as the density is increased, ink consumption increases. With FM network, there is no need to transfer more ink in order to improve the quality of printing. Some printers reported that they were able to use less ink to still obtain prints with a higher density than conventional screens.

31. Ink density

The AM network may print C, M, Y, and K with densities of 1.30, 1.35, 1.00, and 1.80, respectively. However, the FM network may print densities close to 1.60, 1.65, 1.25, and 2.20, respectively, and maintain image sharpness and contrast. The smaller dot size of the FM network limits the thickness of the ink on the paper. Therefore, when the ink density is increased, it is less likely to spread or expand (an initial compensation curve must be used).

Conversely, the larger dot on the plate transfers a thicker layer of ink on the blanket. When transferred to paper, there is a serious increase. This expansion uses traditional dot gain curves and standard (for example, SWOP) compensation for ink density.

32. Computer Direct Plate Making

The plate imaging process will be the same as a regular screen. The only thing to note when using computer-to-plate imaging FM network is that the printing plate used in the screening must meet the strict resolution requirements; the resolution of the printing plate must be able to reproduce the 4 to 8 μm test block on the signal strip; The extreme size of the micro-dots may highlight the problem of resistance to printing.

However, computer-to-plate technology offers the greatest opportunity for FM screening applications. The elimination of film and the elimination of dot gains from film have eliminated this major problem.

Source of information: pack.cn