As the application scope of domestic flexo printing technology becomes wider and wider, and the technology matures gradually, flexo printing-related machinery and equipment and supporting materials have also initially formed a series. Flexo printing is moving from traditional ordinary label products to the high-end packaging and printing market. At present, some domestic cigarette pack printing and folding carton printing companies are also concerned about the application of flexo printing in packaging printing, hoping to use new equipment, develop new processes and new products, and keep up with the development trend of international packaging printing. Let's take a look at a case of choosing a flexo printing machine, and draw some useful revelations from it.

LESHINE CARTON, located in Connecticut in the northeast of the United States, is a large-scale printing enterprise that provides packaging for beverage and food companies. It has offset printing and gravure printing. In 2002, packaging users asked them to provide packaging for cans of beer, which required a group of six cans, environmentally friendly printing, and portable use. There are two kinds of packaging materials, one is a carton, using 0.54mm thick (about 500g) kraft cardboard; the other is a heat shrinkable film of about 30u, which can be matched with the filling line. This request from the customer prompted LESHINE CARTON to develop new processes. In the end, they chose the flexo printing method to meet the new demands of the market, and introduced the Varyflex670 unit type 8-color gearless flexo printing machine from Italy OMET company to print thick cardboard and film products.

The maximum printing format of Varyflex670 is 670X880, which basically meets the requirements of medium format packaging. The machine abandons the traditional long-axis transmission method. The whole machine adopts gearless transmission, that is, the plate cylinder and the impression cylinder are driven by independent motors. Due to some limitations due to gear transmission, thick cardboard and film can be printed on the same device without replacing any components.

For thick cardboard printing, Varyflex 670 uses non-stop unwinding with an unwinding diameter of up to 1500mm in the unwinding section. With a printing speed of up to 200m / min, connected die cutting produces nearly 15,000 finished cartons per hour. Production efficiency is no less than a gravure printing machine. For the drying of 30u heat shrinkable film printing, with the cooperation of the OMET R & D department, each printing unit of Varyflex670 uses a large 24-inch water-cooled roller, and the printing material is wrapped on the water-cooled roller with circulating cold water. It is placed on the water cooling roller to dry the material. In this way, the film will not expand and deform due to heating, which avoids affecting the registration between the color groups. When drying the ink on the ground, increasing the power of the hot air will not change the internal structure of the material, and also avoid accidents such as fire.

In terms of tension control, in order to adapt to a wider printing range, Varyflex670 can call different tension control curves to match different materials before starting the machine. The tension value will be automatically adjusted to the preset range before the machine is started. A three-stage four-stage tension control method is adopted, and a high-sensitivity multi-tension floating roller is used to separate the tension of each part of unwinding, printing, die cutting and winding, without affecting each other. The platen roller driven by an independent motor is very sensitive to tension and can rotate in forward and reverse directions. The unique tension control system provides a good prerequisite for registration.

The registration system of Varyflex670 is very unique because of the gearless transmission method, the registration electrical part of each color group is integrated into the drive motor, and the scanning head can directly feed back the registration signal to the plate cylinder classics, and the traditional servo motor registration Compared with the method, this design not only greatly improves the registration accuracy, but also the registration is very fast. The customer has even made it possible to print 10 colors with an 8-color device (roll to 8 colors first, then print 2 colors plus light) without changing the overprint accuracy. Basically achieved the effect of offset printing, and further reduced the waste of materials.

In order to perfectly achieve the high light and dark tone levels, Varyflex 670 first pays attention to the stability of the machine under high tension and high speed operation. The whole machine wall board uses nickel steel plate up to 3cm thick, and the wall plate in the die cutting area is thickened to 5cm To avoid the loss of dark tone paste or small dots caused by machine vibration, the double-bearing structure is used on the plate cylinder. During the high-speed operation of the machine, the ball bearing is helpful to prevent the axial movement of the plate cylinder and the long flat needle Bearings help prevent radial runout.

In the die-cutting unit, Varyflex670 uses dual magnetic roller technology. The use of yin and yang pair of steel blade skins overcomes the shortcomings of the previous magnetic knife that can only die cut tissue paper, prolongs the service life of the die cutting blade skin, and reduces the use time of the die cutting tool. Three months shortened to one week. When printing thick cardboard, waste scraps are first shredded in the die-cutting unit, and then sent to the waste paper warehouse with a conveyor belt. When connecting thick die-cut cardboard, the printing speed of the machine is not low and 170 meters per minute.

Taking into account the scalability of the machine, Varyflex670 can draw out the ink supply system of each color group along the guide rail, install the cylinder screen printing unit and the rotary gravure unit at the corresponding position, and can flexibly exchange the stations to develop some Unique printing process. Cold and hot bronzing, connection compounding and other processes can also be easily installed at any location. On the platform of flexo printing, the combination of multiple printing processes is truly realized.

In the operation interface, Varyflex670 minimizes the influence of the operator on production. It uses the European patented half-cam pressure control technology, which adjusts the printing pressure and ink supply pressure without affecting each other, and does not rely on the operator's experience; using the sleeve technology not only The labor intensity of the operator is reduced, and the cost of replacing sleeves of different sizes is further reduced. 360-degree automatic pre-registration technology, each printing unit can automatically find the initial position of the printing plate before starting up, so as to achieve preliminary registration. After starting up, only one paper path is needed for complete registration. The waste generated is reduced and the yield is improved. The use of gearless transmission also overcomes the limitation of the gear pitch, realizes the stepless change of the printing repeat length, and is more flexible in layout for products of different sizes during plate making.

Because Varyflex670 was selected, LESHZAIE CARTON entered a new market. In terms of printing quality, its production manager Mr. August said: "When we use UV inks, many technical indicators have exceeded offset and gravure printing." Its marketing manager Mark said: "Varyflex670 has strengthened our market competitiveness after installation We can print materials from extremely thin to ultra-thick, and increase the satisfaction of packaging users. We can flexibly configure the existing flexo production line, the market is wider. "

It can be seen that LESHZAIE CARTON chose Varyflex 670 for packaging printing based on: higher printing quality, wider printing range, easier machine operation, and less material waste.

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