New Solutions for Tobacco Packaging Rotary Printing

Compared to sheet-fed printing, rotary printing is more suitable for large-volume, high-quality cigarette packs. As a flexible printing machine manufacturer with more than 40 years of history, OMET Limited (0MET) in Italy entered into the Chinese market, and based on its experience in cooperation with cigarette printing companies, it has developed some technologies for medium and narrow web transfer printing. Valuable new technologies are shared here with colleagues dedicated to cigarette pack printing.

The following is mainly about the model of shaftless gearless transmission.

1. Link compound. After the composite laser film and paper are combined, they can be peeled off or not peeled off after compound drying. This will not only help reduce the cost of printing materials, but also make them more environmentally friendly. If the positioning printing is performed on the basis of local transfer of the laser layer, the bronzing technology can be partially replaced, and the overlay/transfer and printing overlay accuracy is the same, and a new idea can be explored in anti-counterfeiting.

2. Based on radiant film fixed-length stretching version of the seam avoidance technology. In the laser film production process, the fluctuation of tension and mold temperature caused by the drift caused the laser film distance is not constant. The error in the accumulation of the plate distances causes some printing patterns to be printed on the plate seams during the rotary printing process. The resulting bad film is usually not less than 20% of the material, which brings a huge material waste to the cigarette pack printing company. Omet's seam avoidance technology provides a solution for this. The specific method is to install a plate distance detecting device in the unwinding part of the laser film, and the error of the laser film plate distance is controlled within a certain range through the fixed-length stretching. The printing unit adjusts the phase of the cylinder in real time to avoid the accumulation of plate distance errors. The plate seam on the printing plate and the printing film on the laser film are always overlapped together so that the laser paper can be printed and processed on the rotary machine.

3. Shaftless gearless transmission. The mechanical long axis of the traditional rotary printing press was cancelled. The plate cylinder and the impression cylinder of the printing unit were driven by independent servo motors, and each printing and processing unit was relatively independent. Tobacco packaging companies can flexibly configure their machines according to their product requirements. This simplifies the printing press transmission and eliminates the limitation of the roller gear transmission. The thickness of the printing material is in the range of 0.0l to 0.60mm. Replacement of the film material and cardboard material does not require replacement of any spare parts on the machine. The tension control system also uses non-shaft technology. Each plate cylinder uses an electronic virtual axis, the electronic gear is accurately adjusted to 32 bits, and the registration accuracy is up to 4 millionth, which is much better than the traditional mechanical register method. Because the mechanical structure of the machine is simplified, the operation of the machine is also easy and the daily maintenance work of the machine is also simplified.

4. Sleeve technology. Omet's machines use air-cushioned plate sleeves, eliminating the need for heavy plate cylinders, reducing the labor intensity of the operator's print job changes, and replacing a six-color print within ten minutes. The sleeve is driven by an independent motor, without the limitation of the gear pitch, and the imposition size can be changed steplessly, which is advantageous for saving paper. For special prints, seamless sleeve plates can be used.

5. Multi-process combination printing. Flexible printing, gravure printing, and screen printing have different printing application ranges, and each has its own merits in terms of level performance, on-site printing, and the use of ink for special effects. Omet can insert gravure and screen printing units at different positions of the flexo line. The drive and tension of each process unit are independently controlled and do not interfere with each other, ensuring high-precision overprinting. Cigarette printing companies can flexibly combine various printing processes, flexibly match the features of different products, combine equipment combinations, and avoid weaknesses to develop technological routes that have their own characteristics.

6. Positioning printing. Some laser films have been imprinted on the film during the manufacturing process, requiring printing and pattern overprint on the laser film, which puts special requirements on the overprinting system of the rotary printing press. OMIT's presses use shaftless transmission. The roller motor of each unit can position the pattern on the laser film in both vertical and horizontal directions. Therefore, this type of laser paper also has good adaptability.

7. screen printing. Rotary screen mesh drum plate-making materials are divided into two kinds: woven mesh and electroplated metal mesh. The weaving nets have low plate-making materials cost and flexible platemaking methods, but their ink transfer performance and their own strength are relatively poor, and the printing speed is limited. This type of roller is suitable for products with low quality requirements, and the production volume is not particularly large. It can also be used for white-on-white processes. The metal mesh is welded with a monolithic electroplated nickel mesh, and the ink transfer performance is relatively good. The printing speed is about 50% faster than the braided mesh, but the cost of plate making is relatively high. This method is suitable for products with high quality requirements and large production volumes. In general rotary printing presses, only one kind of material can be used as a screen. Omit's newly-produced screen printing unit can use the mesh drums of the above two materials. Companies can weigh the quality and cost when designing processes, and can use flexible screens. Plate making method.

8. Gravure printing. The gravure has a large amount of ink, and the effect is very good when the printing requires a thick print such as a solid ground ink. In the case of a metal ink printed with particles, it is also stronger than the flexo and offset printing. Omet's installation of a gravure printing machine on the machine can effectively solve the problem of the customer's picking on the hue when the cigarette packet turns from the traditional gravure printing process to the flexo printing process. Gravure printing pressure is much greater than flexo and screen printing. The effect of gravure printing on roll paper force is different from flexo printing and screen printing. In multi-process assembly printing lines, overprinting problems often occur. Omet's method is gravure and flexo printing, and the tension control between screen printing units is controlled. The tension between the units is relatively independent and does not interfere with each other, ensuring accurate printing registration.

9. Compound drying. For water-based inks and UV inks, hot-air, infrared, and UV drying methods are common for flexo printing. In the actual production process, common ink drying is not thorough, and part of the drying system design originated from the equipment is unreasonable. OMIT's printing machine drying system can use three kinds of drying devices to improve the drying efficiency by configuring high-efficiency high-power UV lamps. For the characteristics of water-based inks, the combination of infrared dryers and hot air devices is used to solve high-speed printing. When the ink is not easy to dry the problem.

10. temperature control. Different substrates have different temperature sensitivity, and increasing the drying power in actual production can cause deformation of the material and affect the print registration. Omet is equipped with a large-diameter cooling drum in each printing unit, and the cooling water temperature in the cooling roller is adjustable. The printing material is wrapped on the cooling drum with a wrap angle of nearly 320 degrees. The hot air oven is designed to be mounted on the cooling roller in an arc shape. The UV drying lamp shade can also be placed on the cooling roller. This drying/cooling method allows the most effective control of the temperature of the material, preventing web deformation and ensuring accurate overprinting. There is no difficulty in printing heat-shrinkable film materials that are sensitive to temperature.