Flexo printing, gravure printing, offset printing, and screen printing are common printing methods for packaging and printing. Flexo printing and gravure printing are more distinctive in flexible packaging materials, folding cartons, paper bags, and gift wrapping paper. From the perspective of the development of modern flexographic and gravure printing, there are many similarities or similarities in the structure and technology of equipment, except for the fact that there are major differences in plate making. In order to compare and understand the similarities and differences between the two printing methods in the equipment structure and new technologies, the following will briefly discuss the development and application of flexographic and gravure printing equipment technologies in recent years.
First, the use of automatic traction and tension adjustment device, to achieve non-stop roll change / rewind
The new flexo presses and gravure presses use automatic paper feeders and electropneumatic tension measuring and adjusting devices to ensure constant tension and enable roll change/wind-up without stopping the machine. In order to ensure that the position of the printing material entering the edge of the printing part is always correct, for the opaque material such as paper, an error correction device composed of a photoelectric scanning head or an ultrasonic sensor is also used. When printing paper or paper jams, temperature and humidity adjustments are sometimes required. When printing a plastic film or aluminum foil, a corona treatment device is also provided to improve the ink repellency of the film surface.
Second, the use of independent / direct drive technology to achieve stepless continuous optional print length.
Independent drive technology has been used on gravure printers for many years, but it has been limited to traction, coating, compounding and crosscutting units, and has now grown to full gravure machines that do not require mechanical transmission. In each printing unit, a motor drive is used. The plate cylinder is driven directly by the motor, longitudinal alignment is achieved during the embossing process, and lateral movement is controlled by a stepper motor movement. The main advantages of an independent drive gravure press are the reduction of mechanical parts (no need for mechanical drive shafts and register compensating roller mechanisms, etc.), and the length of the tape is shortened, which helps to improve the printing quality and printing speed.
The plate cylinder of the old-fashioned flexographic printing machine drives the gears of the plate cylinder through the gears of the impression cylinder to form synchronous rotation, and the repeated circumference of the print is the same as the pitch of the gears. In each printing unit of the new flexo press, a motor directly drives the plate cylinder, which solves the problem that the repeated length of the printed product is limited by the gear pitch. Digital drive technology is used to directly drive the plate cylinders. When replacing printing products with different circumferences, there is no need to change gears, and a continuously variable printing length can be achieved. The use of digital control eliminates the need for repetitive speed adjustments, eliminating the need to change the speed and adjust the gear meshing operation, thereby increasing efficiency.
For example, ASTRAFLEX CCI satellite 8-color packaging flexo press newly developed by W&H Company adopts a separate motor drive technology, main drive unit, drive unit for unwinding/winding unit and traction device, with a maximum printing speed of 470 m/min. . The independently driven flexible packaging gravure printing machine developed by Sarudi has a maximum printing speed of up to 500 m/min. The Flexline Vario unit flexo press developed by BHS employs a plateless direct-drive plate cylinder that eliminates the restrictions imposed by the number of gear teeth and eliminates the limitations imposed by the number of gear teeth. Each printing unit has its own Independent servo drive mechanism and quick roll change system with a maximum print speed of 500 meters per minute. The POTOPAK 4000-1 shaftless transmission gravure printing machine developed by Valment Rotomec Company adopts the ES (Electronic Axis) system and does not use the registration compensation roller. In the acceleration and deceleration phases of the machine, rapid register setting can be performed. Increase the stability of the machine. The ES concept uses a fully automatic replacement device that does not require any manual intervention from the operator. The maximum print speed is up to 650 m/min.
With the combination of direct control technology and CI design, as well as the changeability of the print length and the reduction of machine debugging time, the situation in which flexo printing was difficult to print on large and varied webs has changed.
Third, the use of sleeve type plate cylinder structure, to achieve "quick change version."
The plate cylinders of the old-fashioned flexographic and gravure printing machines basically adopt a monolithic structure, while the new type flexographic and gravure machines mostly adopt the sleeve type plate cylinder structure. Because the sleeve type cylinder structure has low cost, loading and unloading are easy. High flexibility, long service life, easy storage, high system accuracy, can shorten preparation time, speed up the replacement of prints, and have "quick change version" function. It is widely used in flexo and gravure printing, and will gradually replace the traditional roller. The biggest advantage of sleeve plate cylinders is that they can be reused. By using different wall thickness sleeves, the plate printing length can be changed.
For example, the newly developed sleeve system from W&H can be used for all types of plate cylinders. After a product is printed, all the specifications that need to be replaced can be quickly replaced by the operator in the machine. The plate cylinder core and the screen are printed. The roller mandrel is always left on the machine. Reuse of rollers not only shortens the preparation time, but also allows plates to be affixed to the sleeve at any time, speeding up the replacement of prints and reducing production costs. The Flexpress16 new 8-color satellite flexo press developed by Fischer & Krecke is used. Thin-walled sleeve technology, low manufacturing cost, can maintain good radial accuracy when printing. The Heliostar 2000 gravure press, produced by W&H, uses sleeve technology with a prominent gravure cylinder to provide printers with greater flexibility and commercial efficiency.
Fourth, the use of closed squeegee system to reduce environmental pollution, is conducive to the rapid replacement of the squeegee
The reverse squeegee structure is used in the quantitative ink supply system, which is suitable for high-speed operation, reduces solvent evaporation and environmental pollution in solvent inks, and solves the problem of foam that accompanies the use of aqueous inks.
The satellite-type flexographic printing press adopts a fully-enclosed double-squeegee inking system. The ink is sprayed on the surface of the anilox roller through the ink port and stored in the ink chamber. After the reverse squeegee is used to scrape the ink, the positive scraper plays a sealing role. Because of its good sealability, it has great health and environmental benefits. In a fully closed system, scrapers, seals, gaskets, and pressure plates are all mounted on a cavity-type bracket, and they are mechanically (or pneumatically or hydraulically) pushed against the ceramic anilox roller and apply a certain pressure. Connect the ink tube and the return tube to the ink pump and reservoir. The use of a closed squeegee system ensures that the anilox roll and printing plate get the optimum amount of ink. The application of laser engrave and closed doctor blade of high-line ceramic anilox roller can ensure the best ink volume for anilox roller and printing plate. Improves the ink transfer performance of the short ink system and improves the quality of printed products.
The Heliostar 2000 gravure press, produced by W&H, uses a newly-developed closed splash protection device that eliminates ink splatter during the cylinder's inking process. The new type of satellite gravure press also uses a squeegee blade to quickly press and replace the device, significantly reducing the time required to change the squeegee and improving the quality of the squeegee. Its structural features are: the squeegee is controlled by a pair of series cylinders. During the production process, the long-stroke cylinder controls the squeegee to enter the predetermined working position, and the short-stroke cylinder controls the squeegee to enter the working position and applies pressure; The rack is equipped with a turnover mechanism (controlled by a tandem cylinder) and a squeegee eccentric clamping mechanism. The former can flip the knife holder to an almost vertical position. The latter can very simply, accurately, uniformly and reliably apply the squeegee holder. tight. Therefore, the entire replacement process can be completed on the machine, and the time is greatly reduced, the uniformity of the ink scraping, the squeegee and the drum life can be improved.
Fifth, printing plate automatic cleaning device
At the end of printing, automatic cleaning of the plate cylinder on the machine can significantly reduce the manual cleaning workload and improve the operating environment. The rapid replacement and cleaning system (Ecoplus) of the Heliostar 2000 gravure press produced by W&H significantly reduced the press setup time. The TURBOLEAN ink supply and cleaning system used by ASTRAFLEX CCI flexo presses can automatically supply ink to printing components and clean the anilox roll, cavity squeegee system, ink pump and ink tube in sequence.
Six, rapid replacement, positioning system
On the transmission side of the gravure printing machine or flexo printing machine, there are guide rods for the small carts. The guide rods move up and down through the cylinders, which can accurately control the movement of the carts and speed up the installation and disassembly of the carts. The PORTACIFT robotic roll change system developed and produced by W&H is used to automatically change plate cylinders and anilox rollers; it takes only 1 minute to replace a roll. Thanks to the intelligent drive system and positioning system, accurate movements and lateral registration of the plate cylinders and anilox rollers of various color groups are guaranteed.
Seven, modular unit structure, diversified forms of post-press processing.
Heirlberg's partner Gallus developed the RCS330 narrow-format flexo press, using all-digital drive technology, full computer control, flexo/silkscreen/offset/embossing, and other printed interchangeable units. Arsoma EM series flexo press adopts optional modular unit and open interface structure. According to requirements, it can be flexibly selected for die cutting, hot stamping, marking, glazing, laminating, embossing, and control. Kind of printing machine.
The FG500 series flexo press produced by Comprint can be configured as a gravure and flexo combined press according to the user's needs.
The B250 unit type 6-color narrow-width flexographic printing machine developed by Edale Company can select the corresponding configuration according to the user's processing needs to complete the holographic anti-counterfeit, UV glazing, hot stamping, stamping patterns, magnetic stripe, die cutter, paper tape Punching, slitting and other online post-processing functions.
The new type of paper gravure, line compounding and die cutting production line developed by Rudy Company is specially used for the printing of cigarette packs and other thick papers. The Tachys (satellite) series of flexographic presses are available in a variety of configurations. They can be connected to a laminated flexographic printing unit for glazing, cold/hot coating, and composite processing.
From this it can be seen that one-stop production is becoming more and more important, and individual production units are moving toward the integration of complete production lines.
Eight, application of computer control technology, intelligent operation and management.
Using advanced computer technology and management systems, it can realize the monitoring system from single control to centralized control, from stand-alone control to the entire production line, and it can ensure that the equipment will not generate waste when registering equipment in the stopped state.
Using a modular, automated operating system, you can preselect menus, centrally operate unwind/wind-up units, printing units, and drying units. You can also use the camera “printing†observation module to view the entire printing process on the display screen. Using CAN communication technology, the functional modules are networked to exchange information. Use modems to select remote troubleshooting devices to help customers.
W&H's newly developed ASTRAFLEX CCI satellite 8-color packaging flexo press coordinates the printing station and the anilox roller with an electronic synchronous adjustment system. The traction device can be set up in proportion, but can also work according to the actual tension conditions.
The B250 unit-type 6-color narrow-width flexographic press produced by Edale Corporation is equipped with a simultaneous print quality inspection device and a computer-controlled automatic registration system. With a variety of functions such as parameter storage, sample content setting, pattern segmentation, and focusing. The registration system is connected to the main control cabinet computer to control the entire production system.
With the establishment of the digital era, the Tachys series of electronically driven printing units and variable-length, high-quality, satellite-type flexographic printers have been introduced.
9. Apply related advanced technologies to improve the quality of printed products
The new flexo and gravure printers use high-efficiency servo stepper motors, which can automatically monitor the speed of rotation to ensure highly accurate settings of printing pressure, print length, plate, and substrate thickness. The DC motor can accurately control the unwind/wind-up unit.
The use of thin-plate technology, computer-to-plate technology, UV inks and high-line ceramic anilox rollers can greatly increase the quality and level of flexographic prints.
First, the use of automatic traction and tension adjustment device, to achieve non-stop roll change / rewind
The new flexo presses and gravure presses use automatic paper feeders and electropneumatic tension measuring and adjusting devices to ensure constant tension and enable roll change/wind-up without stopping the machine. In order to ensure that the position of the printing material entering the edge of the printing part is always correct, for the opaque material such as paper, an error correction device composed of a photoelectric scanning head or an ultrasonic sensor is also used. When printing paper or paper jams, temperature and humidity adjustments are sometimes required. When printing a plastic film or aluminum foil, a corona treatment device is also provided to improve the ink repellency of the film surface.
Second, the use of independent / direct drive technology to achieve stepless continuous optional print length.
Independent drive technology has been used on gravure printers for many years, but it has been limited to traction, coating, compounding and crosscutting units, and has now grown to full gravure machines that do not require mechanical transmission. In each printing unit, a motor drive is used. The plate cylinder is driven directly by the motor, longitudinal alignment is achieved during the embossing process, and lateral movement is controlled by a stepper motor movement. The main advantages of an independent drive gravure press are the reduction of mechanical parts (no need for mechanical drive shafts and register compensating roller mechanisms, etc.), and the length of the tape is shortened, which helps to improve the printing quality and printing speed.
The plate cylinder of the old-fashioned flexographic printing machine drives the gears of the plate cylinder through the gears of the impression cylinder to form synchronous rotation, and the repeated circumference of the print is the same as the pitch of the gears. In each printing unit of the new flexo press, a motor directly drives the plate cylinder, which solves the problem that the repeated length of the printed product is limited by the gear pitch. Digital drive technology is used to directly drive the plate cylinders. When replacing printing products with different circumferences, there is no need to change gears, and a continuously variable printing length can be achieved. The use of digital control eliminates the need for repetitive speed adjustments, eliminating the need to change the speed and adjust the gear meshing operation, thereby increasing efficiency.
For example, ASTRAFLEX CCI satellite 8-color packaging flexo press newly developed by W&H Company adopts a separate motor drive technology, main drive unit, drive unit for unwinding/winding unit and traction device, with a maximum printing speed of 470 m/min. . The independently driven flexible packaging gravure printing machine developed by Sarudi has a maximum printing speed of up to 500 m/min. The Flexline Vario unit flexo press developed by BHS employs a plateless direct-drive plate cylinder that eliminates the restrictions imposed by the number of gear teeth and eliminates the limitations imposed by the number of gear teeth. Each printing unit has its own Independent servo drive mechanism and quick roll change system with a maximum print speed of 500 meters per minute. The POTOPAK 4000-1 shaftless transmission gravure printing machine developed by Valment Rotomec Company adopts the ES (Electronic Axis) system and does not use the registration compensation roller. In the acceleration and deceleration phases of the machine, rapid register setting can be performed. Increase the stability of the machine. The ES concept uses a fully automatic replacement device that does not require any manual intervention from the operator. The maximum print speed is up to 650 m/min.
With the combination of direct control technology and CI design, as well as the changeability of the print length and the reduction of machine debugging time, the situation in which flexo printing was difficult to print on large and varied webs has changed.
Third, the use of sleeve type plate cylinder structure, to achieve "quick change version."
The plate cylinders of the old-fashioned flexographic and gravure printing machines basically adopt a monolithic structure, while the new type flexographic and gravure machines mostly adopt the sleeve type plate cylinder structure. Because the sleeve type cylinder structure has low cost, loading and unloading are easy. High flexibility, long service life, easy storage, high system accuracy, can shorten preparation time, speed up the replacement of prints, and have "quick change version" function. It is widely used in flexo and gravure printing, and will gradually replace the traditional roller. The biggest advantage of sleeve plate cylinders is that they can be reused. By using different wall thickness sleeves, the plate printing length can be changed.
For example, the newly developed sleeve system from W&H can be used for all types of plate cylinders. After a product is printed, all the specifications that need to be replaced can be quickly replaced by the operator in the machine. The plate cylinder core and the screen are printed. The roller mandrel is always left on the machine. Reuse of rollers not only shortens the preparation time, but also allows plates to be affixed to the sleeve at any time, speeding up the replacement of prints and reducing production costs. The Flexpress16 new 8-color satellite flexo press developed by Fischer & Krecke is used. Thin-walled sleeve technology, low manufacturing cost, can maintain good radial accuracy when printing. The Heliostar 2000 gravure press, produced by W&H, uses sleeve technology with a prominent gravure cylinder to provide printers with greater flexibility and commercial efficiency.
Fourth, the use of closed squeegee system to reduce environmental pollution, is conducive to the rapid replacement of the squeegee
The reverse squeegee structure is used in the quantitative ink supply system, which is suitable for high-speed operation, reduces solvent evaporation and environmental pollution in solvent inks, and solves the problem of foam that accompanies the use of aqueous inks.
The satellite-type flexographic printing press adopts a fully-enclosed double-squeegee inking system. The ink is sprayed on the surface of the anilox roller through the ink port and stored in the ink chamber. After the reverse squeegee is used to scrape the ink, the positive scraper plays a sealing role. Because of its good sealability, it has great health and environmental benefits. In a fully closed system, scrapers, seals, gaskets, and pressure plates are all mounted on a cavity-type bracket, and they are mechanically (or pneumatically or hydraulically) pushed against the ceramic anilox roller and apply a certain pressure. Connect the ink tube and the return tube to the ink pump and reservoir. The use of a closed squeegee system ensures that the anilox roll and printing plate get the optimum amount of ink. The application of laser engrave and closed doctor blade of high-line ceramic anilox roller can ensure the best ink volume for anilox roller and printing plate. Improves the ink transfer performance of the short ink system and improves the quality of printed products.
The Heliostar 2000 gravure press, produced by W&H, uses a newly-developed closed splash protection device that eliminates ink splatter during the cylinder's inking process. The new type of satellite gravure press also uses a squeegee blade to quickly press and replace the device, significantly reducing the time required to change the squeegee and improving the quality of the squeegee. Its structural features are: the squeegee is controlled by a pair of series cylinders. During the production process, the long-stroke cylinder controls the squeegee to enter the predetermined working position, and the short-stroke cylinder controls the squeegee to enter the working position and applies pressure; The rack is equipped with a turnover mechanism (controlled by a tandem cylinder) and a squeegee eccentric clamping mechanism. The former can flip the knife holder to an almost vertical position. The latter can very simply, accurately, uniformly and reliably apply the squeegee holder. tight. Therefore, the entire replacement process can be completed on the machine, and the time is greatly reduced, the uniformity of the ink scraping, the squeegee and the drum life can be improved.
Fifth, printing plate automatic cleaning device
At the end of printing, automatic cleaning of the plate cylinder on the machine can significantly reduce the manual cleaning workload and improve the operating environment. The rapid replacement and cleaning system (Ecoplus) of the Heliostar 2000 gravure press produced by W&H significantly reduced the press setup time. The TURBOLEAN ink supply and cleaning system used by ASTRAFLEX CCI flexo presses can automatically supply ink to printing components and clean the anilox roll, cavity squeegee system, ink pump and ink tube in sequence.
Six, rapid replacement, positioning system
On the transmission side of the gravure printing machine or flexo printing machine, there are guide rods for the small carts. The guide rods move up and down through the cylinders, which can accurately control the movement of the carts and speed up the installation and disassembly of the carts. The PORTACIFT robotic roll change system developed and produced by W&H is used to automatically change plate cylinders and anilox rollers; it takes only 1 minute to replace a roll. Thanks to the intelligent drive system and positioning system, accurate movements and lateral registration of the plate cylinders and anilox rollers of various color groups are guaranteed.
Seven, modular unit structure, diversified forms of post-press processing.
Heirlberg's partner Gallus developed the RCS330 narrow-format flexo press, using all-digital drive technology, full computer control, flexo/silkscreen/offset/embossing, and other printed interchangeable units. Arsoma EM series flexo press adopts optional modular unit and open interface structure. According to requirements, it can be flexibly selected for die cutting, hot stamping, marking, glazing, laminating, embossing, and control. Kind of printing machine.
The FG500 series flexo press produced by Comprint can be configured as a gravure and flexo combined press according to the user's needs.
The B250 unit type 6-color narrow-width flexographic printing machine developed by Edale Company can select the corresponding configuration according to the user's processing needs to complete the holographic anti-counterfeit, UV glazing, hot stamping, stamping patterns, magnetic stripe, die cutter, paper tape Punching, slitting and other online post-processing functions.
The new type of paper gravure, line compounding and die cutting production line developed by Rudy Company is specially used for the printing of cigarette packs and other thick papers. The Tachys (satellite) series of flexographic presses are available in a variety of configurations. They can be connected to a laminated flexographic printing unit for glazing, cold/hot coating, and composite processing.
From this it can be seen that one-stop production is becoming more and more important, and individual production units are moving toward the integration of complete production lines.
Eight, application of computer control technology, intelligent operation and management.
Using advanced computer technology and management systems, it can realize the monitoring system from single control to centralized control, from stand-alone control to the entire production line, and it can ensure that the equipment will not generate waste when registering equipment in the stopped state.
Using a modular, automated operating system, you can preselect menus, centrally operate unwind/wind-up units, printing units, and drying units. You can also use the camera “printing†observation module to view the entire printing process on the display screen. Using CAN communication technology, the functional modules are networked to exchange information. Use modems to select remote troubleshooting devices to help customers.
W&H's newly developed ASTRAFLEX CCI satellite 8-color packaging flexo press coordinates the printing station and the anilox roller with an electronic synchronous adjustment system. The traction device can be set up in proportion, but can also work according to the actual tension conditions.
The B250 unit-type 6-color narrow-width flexographic press produced by Edale Corporation is equipped with a simultaneous print quality inspection device and a computer-controlled automatic registration system. With a variety of functions such as parameter storage, sample content setting, pattern segmentation, and focusing. The registration system is connected to the main control cabinet computer to control the entire production system.
With the establishment of the digital era, the Tachys series of electronically driven printing units and variable-length, high-quality, satellite-type flexographic printers have been introduced.
9. Apply related advanced technologies to improve the quality of printed products
The new flexo and gravure printers use high-efficiency servo stepper motors, which can automatically monitor the speed of rotation to ensure highly accurate settings of printing pressure, print length, plate, and substrate thickness. The DC motor can accurately control the unwind/wind-up unit.
The use of thin-plate technology, computer-to-plate technology, UV inks and high-line ceramic anilox rollers can greatly increase the quality and level of flexographic prints.
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