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Recommend a clever solution for embossing to flexo
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Prepress: The prepress concept of embossing and flexo is not the same
The embossed dots on the print have two-dimensional properties similar to the size and thickness of the gravure dots. On a embossed plate with both solid and dot, the depth of the local dot is determined by the number of dots set by the prepress. The captain can also control the thickness of the ink layer of the dot by the local ink key control, thus affecting the printing color. depth. And the depth depends on the actual printing dot impact dot mesh pattern surrounding its ink passage. These uncertain factors cannot be controlled in advance. Therefore, the pre-press color correction of embossing is only principle and principle. There is no specific working standard. The captain can only help to make some local detail adjustments before printing. The embossed pre-press finish is more like door art than just door technology.
The flexo dots are one-dimensional. On a flexo plate with both solid and dot, the ink thickness of the dot is the same as the thickness of the ink in the field. It is determined that the local depth of the dot is completely in front of the print, which is determined by the characteristics of flexographic printing using an anilox roller to quantitatively transfer ink. of. It is because of this feature that the captain's control of the color is to change the entire layout to the same depth or shallow by changing the anilox roller, and not just to change the part. This also makes flexo the most stable printing method in history. Also because of this feature, when proofing, because the captain can not make the local deepening or lightening, the flexibility of proofing is relatively poor. “Before the seven-point printing, three-point printingâ€, the importance of pre-press is more prominent in flexo printing. Due to the stability of the flexographic parameters, it is necessary to establish a standard according to the characteristics of the machine before the press, and launch the analog proofing system, so that the effect of 80% to 90% can be expected before the official launch. Therefore, the pre-press color correction of flexo printing must rely on the data plus color correction experience to complete.
Rotary embossing machines require an experienced starter, and flexo printing requires a strong prepress. However, label printing companies can hand over the prepress work of flexo printing to professional prepress companies. In this way, label printing companies can concentrate on printing. It should be noted that this does not mean denying the role of the flexo captain. Good flexo captains and poor flexo captains can make completely different quality prints.
Process design link: organize relevant personnel to discuss the process and further prevent the problem
1. Overprinting problem: The printing accuracy of the satellite printing machine is higher than that of the unit printing machine. Therefore, it is necessary to properly handle the partial trapping problem during prepress processing, instead of relying solely on the standard. For example, if black ink is overprinted on a light ink, it can be done to make the trapping white to 0.3mm. The printing machine with automatic alignment device can make the color of the overprinting requirement be the color of the cursor. If the printing machine does not have the automatic alignment device, the color plate with high overprinting requirements should be arranged on the adjacent color group as much as possible. .
2. Blocking problem: For flexographic process engineers, what can be done is to print in the field and dot-sorting, and even use two light-colored dots to print deeper colors to reduce the risk of blocking. However, the problem of blocking is not solved by the entire flexo industry. Although many companies have made various efforts, some use low surface energy plates, some use online screening technology, some expect the captain to control the three-roll pressure, and even some use the Gulf flow anilox roller, but These are quantitative improvements, not qualitative changes. In the future, we need to work together to tackle the problem.
3. Ink bar problem: Most of the fixed ink bars produced by the old flexo printing machine belong to the ink bar caused by the damage of the machine parts. It can be solved by replacing the parts or repairing the machine. However, if the ink stick is not fixed, it is a embossed and flexo-printed "hard to heal." The usual solution is to reduce all possible vibrations, such as widening the beading, staggering the blank and non-blank parts of the graphic, filling the gap, etc., which can greatly reduce the generation of the ink bar. For companies that need to introduce new flexo presses for embossing and flexo printing, servo-driven flexo presses and flexo presses with plate roll support are very effective in avoiding ink sticks.
4. Combined proofing, mass production by volume: Due to the accuracy of the amount of ink transferred by the anilox roller and the one-dimensionality of the flexographic dot on the printed product, the ink consistency of the entire flexographic printing plate is very high. Many color flexo prints that belong to the four-color overprint can be proofed together when proofing, so as to save the cost of proofing; In this way, the color of the flexo will not be affected, but it is not suitable for the embossing.
5. Small version proofing, large version of mass production: also based on the above reasons, in order to save the proofing cost and possible revision costs, flexo printing can be used to repeat the size of the plate on the perimeter to be proofed, after the customer confirms and then fight Large version to print.