An Analysis of the Prepress Technology of Folding Carton Flexo Printing

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As all carton printers know, the market prospects for folding carton printing have become dimming in the past few years. Customers are increasingly demanding the quality of printing, and prices are becoming more and more at the bottom, causing some printing companies to be forced Fade out, and more printers feel the pressure to survive. In recent years, many printing companies have found a very good solution to the difficulty of printing folding cartons using a web-fed flexible printing line. Flexible printing can be comparable to offset printing in terms of quality. The quality of most carton products can be accepted by users. The use of web printing production lines enables most carton printing processes to be completed at one time, which brings huge economic benefits to the adopters.

First, prepress

Graphic manuscript
Flexo manuscripts are also in digital format. The hardware and software used in offset printing are also used in flexo printing. The difference is that the two methods for processing original documents are different. For example, the color separation process is different because of the high density of flexo dots. Flexo printing is more versatile in color separation because the flexo press can do more color adjustment than offset printing. Whether thick or thin lines, flexo printing can be better color combinations, higher density and better color reproduction.

Film/traditional platemaking

Many printing and prepress workshops still use traditional films and plates in large quantities. Although digital platesetters have their own advantages in terms of process and print quality, traditional plates will continue to be used for quite some time. The quality of the film that is to be used depends on the quality of the film produced with the modified file. The film is used to make a photographic printing plate. The plate is washed, dried and processed to be mounted on a plate cylinder. The plate cylinder is repeatedly printed. Traditional printing plates have advantages for printing specialized jobs.

Digital media

Digital platemaking is the latest technology and has many advantages over traditional plate making. Eliminating film is the key. More importantly, the improved printing characteristics (with better dot structure) can improve the quality of flexo printing to a new level, and can even compete with the traditional offset printing market. The digital media is imaged with a laser head, exposed, rinsed, and processed for printing on a plate cylinder.

Prepress material supply and interior plate making processes

Like offset printing, flexographic prepress material can be produced in-house or purchased from a dedicated prepress material supplier. In order to control costs and shorten the printing cycle, more and more companies are processing in their own workshops. What is common is that many parts are completed in the workshop themselves, and those difficult jobs are given to professional companies because of their rich experience in this area.

Second, printing

Water-based inks, UV inks, and coatings

Each ink has its own advantages and disadvantages. It has to be considered comprehensively, and market factors play a decisive role. What is common to both systems is the consistency of color and the quality of color reproduction. The printer's adjustment of the anilox roller and doctor blade has little effect on color. The correct color and the selection of the anilox roller are related to the nature of the ink, and the operator does not have much to do with adjusting the knob to adjust the amount of ink.

Aspects to be mastered when copying printed materials

If the same color pattern is used on the same anilox roller, the copied color is the same. In today's flexo printing, coating and laminating processes can also be added to the folding carton printing process, which adds more added value and reduces costs. UV, water-based and EB coating oils and glues are widely used. When choosing the ink system, the selection of UV, water-base and EB coating oils and glues must be based on actual conditions.

Film considerations

The type of film base will have a great impact on the print quality of the carton. For example, a smooth surface will have less dot loss and better color reproduction than a rough surface. The brightness of the paper tray will affect the overall appearance of the paper tray. A dark, matt surface will affect the printed ink color. Modifying and correcting before making a plate can reduce the impact of this situation.

Integrated use of ink, anilox and plates

In any flexo printing, only the equipment, ink, anilox roll, film base, plate material, and coating oil/glue are used in combination to achieve the highest quality in folding carton printing. All these improvements can make flexo printing comparable to offset printing. Although not all offset prints can be imitated with flexo, most of them are not problematic. For example, high-line anilox rollers are used with the latest high-strength inks, and digital printing plates can be used to print clear, sharp dots.

Achieving offset printing quality does not mean that flexo printing can also be printed like offset printing. For example, there is a huge difference in the number of colors, ink color sequence, and prepress technology. This information is sometimes known to end customers who are accustomed to offset printing. The customer is more concerned about the printing effect, but there is not much interest in what method to print. This is sometimes a challenge for flexo printers, but it is very important to convey the message to the customer so that the customer does not attempt to completely relocate the flexographic requirements to flexo. (to be continued)

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