What about flexo blocking?
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Flexographic blocking (also known as stencil) is the pain of most flexo printing machines. In flexo stickers, high color contrast and gradual smashing are common, and such designs can easily cause flexographic blocking.
One of the reasons that usually cause flexographic blocking is that the smallest dot is immersed in the anilox roller mesh. Today, the label will share this topic with you.
In the case of a blocking failure of 20% or less, especially 5% high-gloss dots, the flexo capper not only controls the three-roller pressure (anilox roller, plate roller, embossing roller) but also sprays on the highlight of the printing plate. There is no other more effective way than silicone oil.
In fact, solving the problem of flexographic blocking is not only the responsibility of the flexor captain, but also the responsibility of the prepress staff, and it is the responsibility of the product technician.
The so-called "three-point printing, seven-point printing plate", from the design link, is destined to the high and low print yield and the speed of printing. Therefore, the quality of printing is not only manufactured, but also designed.
Design is rainy
In the flexographic daily label, 150 lines/inch and 175 lines/inch are commonly used screen lines. If the small dot falls into the cell of the anilox roller, it will cause blocking, and 1% or even 2% of the small dot should be avoided as much as possible during the process arrangement.
If there is a net in the printed image, use 2% to 3% of the dot; if there is no high-gloss dot in the printed image, increase the number of plates to 200 lines/inch or even more. High to improve the delicateness of the print.
I believe that as long as there is good communication, customers usually respect the opinions of label printing companies. But what if the customer takes the offset or gravure samples to track the samples?
If you want to meet the 0 to 100% gradient, the depth of the field, the problem of shallow points, what should I do? This requires product technicians to play an important role in product design.
Product technicians are responsible for process evaluation and design throughout the process and prevent possible risks such as overprinting process design, avoidance of ink bars, prevention of blockage, and comprehensive cost control of typesetting. The aim is to meet the requirements of the customer and the smooth mass production under the lowest cost conditions.
How to deal with the absolute network sample
So, how to avoid flexographic blocking when chasing offset or gravure?
First, choose the number of screened lines, such as 175 lines/inch, instead of blindly chasing the high line number of offset printing. When chasing the sample, the samba network (frequency modulation network) can not be printed too deep, the pressure can not be too large, otherwise it does not meet the Asian aesthetic.
When using Esko HD high-definition dots, since the number of 1% dots is reduced to only 0.3% of the dots, the dot version and the solid version should be separated as much as possible, and the separation should not be strictly followed. "The minimum dot is not immersed in the mesh roll. "the rules.
2016 "Sun Cup" chemical bronze award-winning works - Shell oil label, multi-layer, good gradient effect, especially the transition between the highlights and gradients is even and delicate, the overall effect of the label is strong, and the printing effect of metal materials.
Second, the gradient from shallow to deep, as long as the dark adjustment part of the dot is not 100%, the pre-press separation should increase the percentage of the dot to increase the number of anilox lines to ensure that the color of the print is not affected.
Third, use inks with high color density or American inks. The color density of the ink is increased, and the BCM value of the natural anilox roll can be lowered, and the corresponding number of anilox rolls can be increased.
Fourth, for a 0 to 100% gradation, even if the printed dark area is too shallow, the method of reducing the number of anilox lines cannot be used, and the method of printing twice can be adopted.
For example, the label used for the 200ml Lux shower gel is a gravure shrink label, and the label for the 1000ml Lux shower gel is a flexo sticker. The customer requires that the flexo label must be followed by a gravure shrink label sample.
Due to the two-dimensional characteristics of the gravure dot, the mesh point is shallow and small, and the printed product has no traces of the mark. The gradient to the dark tone is large and deep, and the color is full and thick. In the case of the flexo printing, the Samba network (also available with Esko HD dots and Kodak Flexcel NX dots) can be used to secretly call the AM network and use 1000 lines/inch to supply ink to the web roller. Blocking.
The printing method of two passes is adopted, but the printing of the second pass is only printed at 1% to 100% in the middle and dark adjustment of the first printing of the graphic to increase the dark tone level.
Such a print can not only adjust the field and the mesh, but also reduce the occurrence of dirty spots, avoiding the problem that the gravure is very difficult to solve the jump (70% at the same level).
In addition to the minimum dot immersion in the anilox roll cell, the three-roll pressure control is not good enough to form a dot bridge, the surface tension of the plate is not matched with the ink, and other thick layers such as ink layers and dark-adjusted bridges are also common causes of blockage. And wait for the label to share with you next time!