Discussion on Combination Printing Technology

Combined printing refers to a flow production line made up of various types of printing and postpress processing units. In combination printing, various printing processes such as flexo printing, screen printing, embossing, and offset printing can be mixed and used. Common combination printing units usually include silk screen, flexo, embossing and hot stamping units. At present, the development of numerous related technologies has made people feel that combination printing has adapted to the needs of the development of the modern printing industry and has brought substantial economic benefits to manufacturers.

First, the combination of printing is the product of continuous development of printing technology

With the ever-growing prosperity of the printing market, modern people have become increasingly demanding in terms of print, and many new processing technologies have emerged. Printing companies are also striving to find a printing method that can achieve a variety of technological effects on the same product. Therefore, this kind of line-type combined processing method capable of simultaneously completing a plurality of printing processes in one printing process becomes a subject of people's choice.

On the other hand, various printing processes have their own inherent advantages and disadvantages. For example, the graphic art of offset printing and embossing is good in definition and the printing speed is high, but the hiding power is poor, and the equipment purchase cost is high; the screen printing can be regulated. The accumulation of a thick layer of ink, with excellent hiding power, and low equipment purchase costs, but the printing speed is very slow; and flexographic printing, whether it is hiding power, printing speed, clarity or acquisition costs are in the middle position. It is the purpose and significance of the combination printing that the best characteristics of these printing methods are brought into full play to form a comprehensive and perfect production line.

The advanced printing equipment, high-quality printing materials and other high-performance auxiliary materials, especially the UV-curable ink technology, have become an important factor in promoting the development of the combined printing process technology.

UV curing inks have made significant progress since entering the market in the 1980s and have played a leading role in the silk screen industry. The strength of UV-curable inks is reflected not only in the process of processing but also in the quality level of printed matter compared to other ink-curing methods.

From the processing point of view, the advantage is that the curing process of the UV ink is very stable, and the entire process needs only to be completed from under the UV lamp. This process allows printing, hot stamping, die-cutting and other post-printing processes to be carried out on a single machine for continuous production, so that maximum productivity can be achieved with minimal effort during processing. In addition, the good adhesion of UV inks is suitable for a variety of substrates, including plastic films that have been difficult to handle in the past, such as BOPP, PET, polystyrene, and coextruded composite films. Due to the excellent adhesive properties of UV inks, the pre-press assistive working time is significantly reduced. There is little adjustment work on the press and no other additives have to be added. When the printing stops midway, the ink on the glazing roller and the anilox roller will not dry. The surface of the UV ink layer has extremely high abrasion resistance and chemical stability, which is also the main reason why the label product adopts combination printing. UV inks have high hiding power and gloss, and the clarity of printed products is also very high, which fully reflects the end-user's demand for product quality.

The important points to note in the three combination printing

Since the combination printing is a complex of various printing processes, its operation will have a certain degree of difficulty. In practical applications, the following points must be noted:

1. It must be ensured that the sequence between each unit of the combined printing press used is sufficiently variable to adapt to the combination of printing processes required for various printed matters. In general, the hot stamping unit is placed at the terminal of the printing unit.

2. Test the ink compatibility before printing. Because the composition of the ink used in different printing processes is different, and different inks are not compatible with each other, the ink used in two different systems will have the problems of overprint rate and adhesiveness; Incompatibility with other post-print finishing processes such as hot stamping, inkjet, and laser printing. Ink and other consumables are best understood by manufacturers and suppliers.

3. The color matching of ink in combination printing must be trained in regular color matching, and equipped with advanced color matching equipment such as spectrophotometer, etc., because when the same color is used for ink color matching of different printing processes, the manufacturer usually chooses different substrates. The production of pigments means that problems occur when using inks of different processes, such as screen inks and flexo inks, to match colors.

4. Set the printing unit speed according to the printing requirements. On a combination press, the printing speed is always controlled by one of the slowest ones. For example, a flexo printer can use UV inks at speeds of up to 300 feet/min. If the speed of the machine is only 100 feet/min, when the print is hot, it cannot reach 300 feet/min.

Of course, combined printing is still at the beginning stage, and there are many technical issues and material issues that need to be explored and improved. But there is no doubt that with the increasingly personalized and diversified printing, the combination printing will be widely used.



Source: "Printer"