Corrugated carton direct flexo prepress design (below)

Second, pay attention to the use of levels

Because of the different tastes of the designers, the characteristics of the products are different. Therefore, there are differences in the style of packaging design. Some of them are pursuing simplicity and some are rich in pursuit. However, if its design works are achieved through flexographic printing, the use of layers in design must attract the attention of designers.

Because the flexible version is a letterpress, the material is highly flexible and deformable, so the dot gain after press is more serious, and in the process of plate making, 1% or 2% of small dots are easily lost during the printing process, during the printing process. The medium can't be reproduced very well. 3% of the outlets will expand to about 10% after printing. It is impossible to achieve a very smooth or gradient effect from 100% to 0%, so the highlights and darkness that the flexo products can express There are relatively few levels in the adjustment area, and the high-yield products with good prints can only reproduce 8% to 10% of the outlets. Therefore, less than 8% of the dots in the design will not show up in actual printing. Such as the use of gradient color, if the network gradient to 0%, in the small network or to have a clear boundary or seal, thus affecting the packaging image. Although each manufacturer has its own way to overcome or solve this problem, flexo printing cannot match offset printing anyway. This feature of flexo is only taken into account when designing to achieve your design after printing.

Another example is the fact that the edges of the image are dimmed, and if they are dimmed to a net, the aforementioned problems will also arise. This requires the designer to consider avoiding the emergence of such problems in the packaging design.

In addition, as mentioned earlier, the number of anilox roller lines used in flexo-ink transfer is different for halftone and field versions. Large areas are connected to local gradients, and printing is very difficult. In particular, the manuscripts with darker colors in the field take care of the part of the mesh tone, and the actual printing on the ground is not true or the color is light; taking care of the field, the halftones are partially stenciled and have dirty spots. Although it can sometimes be solved by selecting an anilox roller with a moderate number of lines and reducing the number of screen lines in the halftone portion, it is in any case inconsistent with the original intention of the designer.

It is worth mentioning that in packaging design, gold and silver ink are often used to enrich the packaging design and improve the packaging quality. When using gold or silver ink, if the pattern contains a halftone, it is better to leave more space in highlights and shadows. The best light spot is better than 20%, because such ink printing dots are easy to paste.

Third, consider printing registration

Like offset printing and gravure printing, flexo printing also involves overprinting problems. In the design of flexo packaging, on the one hand, we must pursue the exquisiteness of the pattern. On the one hand, we must also consider the difficulty of printing. For example, for small texts and designs, to be represented by overprinting, it is difficult to guarantee the accuracy of overprinting, which will inevitably lead to an increase in the rejection rate or unsightliness of printed patterns. Trapping is usually used to solve this problem. Trapping of corrugated boxes is usually 0.5 to 1 mm, sometimes slightly smaller for different printing presses. If under such a big trap, the printing of texts and patterns has difficulty, it must be adjusted accordingly. In particular, the overprinting of complementary colors, the black border will appear at the junction of the two colors, affecting the beauty of packaging. Relatively speaking, dark and light-colored overprints will be much better. In addition, a set of text or color blocks overprinted by multiple units also increases the difficulty of printing. Since most domestically used flexo presses are driven by gears, a deep, light, or two-color regular pattern of color blocks or lines appears in the packaging design, which also causes difficulties in printing.

The embossed pattern on the flexographic plate is formed by brushing off the unexposed portions with a solution of the printing solution and a brush, so the flexographic plate is required for the size of the smallest character and the finest line. For corrugated box printing, we recommend that the finest line should not be less than 0.5mm. If it is an isolated line, it should be appropriately widened. As for the text, the thickness of the stroke is best referred to the above data. Because the stroke structures such as the bold typeface and the Song typeface are different, it is not easy to uniformly set the minimum size. Pay special attention when using the "Dar Song" font because the contrast between the horizontal and vertical lines is too large.

In the use of barcodes, because the flexographic plate is easily deformed in the printing process, the plate material is flatly attached to the circular cylinder and must be deformed. Therefore, attention must be paid to the barcode processing. For different printing machines and different bar code sizes, each bar code must have an amount of reduction beforehand in advance of platemaking to ensure that it can be detected after printing. Of course, this reduction is done by the plate-making manufacturers. Here, the designers should pay attention to the direction and size of the bar code. The bar code size should be based on the standard, and the bar code direction should be consistent with the printing direction.

Fourth, pay attention to the layout of the packaging design effect

In the packaging design, the general designer only pays attention to the finished product effect and flat effect of the packaging, and seldom pays attention to the layout effect of the packaging. Printing is a mass production process. It is necessary to arrange the packaged single figures according to the width of the printing press and the circumference of the printing roller. Therefore, the effect of typesetting must be taken into account in the design. Especially when the individual patterns need to be repeatedly arranged, the colors of the intersecting positions should be the same or the connected pattern designs are continuous, so as to avoid that the partial patterns on a package appear in isolation on the plate due to die-cut deviation after printing. Another packaging that causes the finished product to be unsightly. This type of layout should be avoided as much as possible during design.

The above-mentioned problems involved in typesetting are all small-size packaging. In fact, many of the corrugated-paperboard packaging are large-sized, such as refrigerators, monitors, etc. When designing these large packaging, it is necessary to consider the film output and plate-making dimensions. limitation. At present, the maximum size of the flexographic plate in China cannot exceed 2000mm×1320mm, and the film output is mostly within 1100mm×800mm. When carrying out large-scale packaging designs, the characteristics of these processes must be taken into consideration. Patterns exceeding these sizes are best not designed as a continuous pattern or an overall pattern. Once it is designed in this way, it is necessary to splicing the plates before printing, and then splicing them carefully. After printing, a clear interface will appear on the patterns, which will greatly affect the exquisite degree of packaging. When designing, only considering the convenience of disassembling the large-size packaging printing plate can make the printed product meet the designer's creativity.

V. Try to use vector software when designing

At present, most designers use computers as a tool to present their ideas. The design software is in vector form, such as Illustrator, Freehand, CorelDRAW, etc., in the form of pixels, such as: Photoshop, Panit, etc. Do not all during the design process. Using Photoshop and other pixel-format software, Photoshop is best used to process images or create some special effects. Other lines, text, and color blocks are best created with vector software such as Illustrator, Freehand, and the manuscript is sent to the platemaking company. Platemaking companies can more easily and quickly make some adjustments to the design drafts for the characteristics of flexographic printing, such as trapping, drop curves, etc., to achieve the effect of convenient printing. When designers send their design work as electronic data to the printing manufacturers or plate making manufacturers, it is best to convert all the texts in the design draft into a path before data storage, so as to reduce the receiver's ability to change the font due to incomplete fonts and other reasons. . If you need to change the text more or do not turn the text into a path, you should send the corresponding font and design manuscript to the data receiver.

In short, to print good printing effects through corrugated cartons direct flexo printing technology, the characteristics of corrugated cartons flexographic printing technology must be fully considered from the manuscript design stage, and this also requires designers, plate-making manufacturers, printing manufacturers, and end-users to work together. Efforts to negotiate.

--"Printing Technology"