【Introduction of four-color printing machine】Four-color printing machine principle Four-color printing machine operating procedures
Principle of four-color printing machine
Nowadays, printing presses are usually screen printing, and four-color overprinting is the most common. In PS you can see four channels of CMYK, if the image is CMYK mode. Can imagine using these four channels to make four films, and then the four films stacked together to see the light transmission, is probably the principle, according to the distribution of the four colors in the picture red, yellow, blue and black to make four screen plates, generally with the principle of sunlight to make, and then use the screen plate to print a color, dry, and then print the second color, until the four colors printed. At this point, some colors are stacked together. Such as orange, is printed once red, once yellow, stacked up is orange. Although theoretically you can use the red, yellow and blue colors to produce black, but in practice it is not feasible, because the mixing of colors will lead to a decrease in vividness, the final result is a gray-black, so add a black version of the three primary colors in red, yellow and blue. In PS, black is red, yellow, blue and black four colors are mixed together to mix out, but in the printing of such settings will not work, because mixed together the vividness will drop. So generally only use the black and blue two channels to print the black part. By the same token, printing or printing cannot produce very bright colors, so RGB mode has a much larger color range than CMYK mode. When taking colors in PS, a triangular warning mark often appears next to the color, which means that the color cannot be used for printing.
Four-color printing machine operating procedures
Standardize operations to ensure orderly production.
2、Scope of application
Suitable for the production of four-color printing slotting die-cutting machines.
The operator of this machine must strictly abide by the workshop safety production procedures, master the process technology procedures of this machine, conscientiously implement the operating procedures, and strictly prohibit illegal operation.
(2) The main and deputy operators of the machine are responsible for the gatekeeping of the film board entering the machine and the quality control during the production process. To ensure the production of qualified products.
(3) The main operator is fully responsible for the safety production of this machine.
（1）Start-up preparation procedures
A、Main control panel operation
①The upper row of the host start, stop button: press the left button host start: press the right button, host stop: The lower row: the left for the host deceleration adjustment button; the middle for the host automatic zero button; the right for the host acceleration button; speed is displayed on the left display
②Vacuum adsorption (commonly known as under the wind) switch points to the left, the motor stops, the switch points to the right, the fan began to work. The right side is the speed button, press "+" to increase the air volume, press "-" to reduce the air volume. Bending piece in time to adjust the wind volume, so that the bag fully adsorbed in the grille.
③Dust suction control: press the left button of dust suction (commonly known as upper suction), the fan starts working, press the right button of the fan stops working.
④Press the left button to start and stop printing: Press the left button to start inking the anilox rollers of each color printing section and to start film feeding the grille of the bag feeding section. Press the right button, the anilox roller of each color printing section starts to rise to stop inking, and the grille of the bag feeding section rises to stop film feeding.
⑤Left and right flap adjustment switch: The left side is left flap adjustment switch: the switch is twisted to "+" to move the left flap to the left, the switch is twisted to "-" to move the left flap to the right. The right side is the right flap adjustment switch: the switch is twisted to "+" to move the right flap to the right, the switch is twisted to "-" to move the right flap to the left:
The upper side is the left and right flap adjustment switch at the same time: the switch twists to "+" the left flap moves to the left and the right flap moves to the right; the switch twists to "-" the left flap moves to the right and the right flap moves to the left.
⑥Back baffle adjustment switch: switch pointing to the left, the back baffle moves forward, switch pointing to the right, the back baffle moves backward. The lower curved film plate should be shaken low back stopper, and the upper curved film plate should be shaken high back moving version to make the bag enter smoothly.
⑦Emergency stop button: In case of emergency, press the emergency stop button immediately
⑧Bag delivery control panel: Wall lock button: Press the button to light up, the wall lock is open and the unit can be moved. Press the button, the indicator light is off, the wall lock is locked, and the unit cannot move.
⑨Move the switch: The car wall lock opens, the left button machine closes, the right button machine separates.
⑩Host inching (pointing) button: Press and hold this button, the host runs at slow speed.
B、Feeding department operation:
According to the production task list, process list, printing sample requirements, adjust the rules of the feeding section, twist the side handle of the front gear plate, adjust to a printing film plate can be easily passed, adjust the side gear plate, rear baffle and suction system to the appropriate position. Use this single from the film plate line to try to put the appropriate film plate, that is, the adjustment is complete.
（2）Upper version of the operating procedures
A、According to the plate number on the production task list, extract the plate and check whether the plate and the printing sample (or sample box) are identical.
B、Pull open the unit, find the center line, step on the foot switch and turn to the fixed slot of the hanging plate, send the printing plate into the hanging slot. Step on the foot switch to drive the printing plate upward, turn to the lower end of the clamping plate activity slot, move the operating side of the plate roller with a moving hand to tighten the ratchet up the printing plate, check whether the plate is flat, the position is correct. No error before starting the printing machine.
C、After printing, pull open the unit and foot switch to the position of the active slot of the clamping plate. Remove the printing plate by loosening the ratchet at the side end of the operation with the moving hand, and after cleaning, store it in the plate cabinet according to the number.
（3）Slotting department operating procedures
A、First slot the slotting knife into the slot, adjust the slotting knife position and front and rear knives and knife distance according to the size demand of the process sheet.
B、The grooving part and the whole machine should be separated when adjusting the grooving knife to avoid the injury caused by the rotation of the machine.
C, before and after work should be timely clean up the knife shaft film chips, and lubrication work.
D, die-cutting department adjustment:
①Move the slotting knife to the sides, just pressing the edge of the membrane board by 1cm.
②Adjust the press line, pre-pressure and cutter pressure to 0.4-0.5mm less than the thickness of the film sheet to ensure that the film sheet enters the die-cutting section smoothly.
③Center the template to the die-cutting rollers, on the template is to reduce the pressure to separate the die-cutting from the whole machine.
④When installing the template, the screws are installed from the bottom of the template first, and the screws should be installed from the joint of the two pieces of template to both sides first. The main reason to consider the lower pattern, die-cutting is the lower edge of the template first contact with the Urethane, and the screw holes of the template try to install all the screws to ensure the true roundness of the template.
⑤When adjusting the position of the template, the template should be separated from the Urethane first and staggered before adjustment to avoid damage to the template and Urethane.
A. After each shift is finished, you must wash the inking roller and the ink on the rubber roller with water, and then detach the rubber roller from the inking roller. Otherwise, it will cause damage to the inking roller and rubber roller and cause great loss.
B、After each shift, clean the site hygiene, wipe the equipment, count the tools, fill in the shift record, etc., before leaving work.
Four-color printing process Q&A
1、What do you mean by four-color printing?
The four-color printing process generally refers to a printing process that uses yellow, magenta and cyan inks and black ink to reproduce the various colors of a color original.
2、What is meant by spot color printing?
Spot color printing refers to the use of yellow, magenta, cyan. Black ink four-color ink other than other color ink to reproduce the original color printing process. Packaging printing often uses spot-color printing process to print large areas of the base color.
3、What products must use the four-color printing process?
Photographs taken by color photography reflecting the colorful changes in nature, color artworks by painters, or other images containing many different colors must be scanned and color-separated by electronic color separation machines or color desktop systems for technical or economic reasons, and then reproduced using a four-color printing process.
4、What kind of products are used for spot color printing?
Packaging products or book covers are often composed of different colors of uniform blocks or a regular gradient of color blocks and text, these blocks and text can be divided into four primary colors after the use of ink overlays, but also the deployment of spot-color ink, and then only printed at the same color block of a spot-color ink. In the comprehensive consideration of improving the quality of printing and saving the number of overprints, sometimes to choose spot-color printing.
5、What is the difference in the visual effect of color between a block of spot color printing and a block of color printed in four colors?
Spot-color printing is blended out of the ink is in accordance with the principle of color subtractive color mixing method to obtain color, its color brightness is lower, higher saturation; ink uniform spot color block is usually used for field printing, and to appropriately increase the amount of ink, when the layout ink layer thickness is larger, the ink layer thickness change on the sensitivity of color changes will be reduced, so it is easier to get a uniform ink color, thick printing effect.
6、From the perspective of improving product quality, what kind of products are suitable for spot-color printing?
In the printing of large areas of light uniform color block, usually used in the original ink added; in light agent to deploy spot-color ink, and then field printing, so that the ink layer is thicker, it is easier to get uniform color, thick effect. If the four-color printing process, it is necessary to use a low number of flat screen dot. However, the low number of flat screen network in the sun easily by the tiny grit or pumping slightly bad caused by individual parts of the network becomes smaller, resulting in uneven ink color, and easy to print because the layout of the water supply too much. Paper powder in the printing plate and rubber blanket accumulation, paper smoothness and other reasons caused by small network of ink transfer bad. Thus, the ink color lightening and uneven ink color.
7、From the point of view of economic efficiency what kind of products are suitable for spot color printing?
Considered from the perspective of emergency benefits, mainly depends on the use of spot-color printing process can save the number of overprints. Because reducing the number of overprints can save both printing costs and pre-press production costs.
8、Can a product be printed in both four colors and spot colors?
If the picture of a product has both a color level screen and a large area of the base color, the color level screen part can use four-color printing, while the large area of the base color can be used for spot-color printing. The advantage of doing so is that: four-color printing part of the field by controlling the density of the picture can be correctly restored, the bottom part of the ink by appropriately increasing the amount of ink can be obtained evenly thick visual effect. This method is often used in the production of high-grade packaging products and stamps printing, but due to the increase in the number of colors, but also makes the cost of printing plates increased.
9、When using four-color printing process, such as nine, if there is a large area of black field, how to make plates more conducive to black field ink thick?
With four-color printing process, in order to ensure the correct restoration of order and color, the thickness of the ink layer of each color should be strictly controlled. Usually in four-color printing, black field density of no more than 1.8, to such a density of printing large areas of black field, will lack the visual effect of thick. Commonly used force method is in the large area of black field part of the overprint of about 40% cyan.