The Flexo printing machine is the key to the whole flexo printing. All print data comes from the flexo press, and in every print job preparation measure, the quality of work and careful maintenance of the equipment contribute to a successful print. Successful printing depends on the level of technology used, the skills of the operator of the Flexo printing machine, and the mechanical properties of the flexo printing machine itself.
Installation of Flexo printing machine anilox roller, plate roller, and printing:
Flexo printing machine The printing unit is the main component of the machine, which completes the main process of printing: including ink supply, printing, drying, etc.
1 Cartridge on Flexo printing machine
Upper ink cartridge: For the positioning of the ink cartridge, first support it by hand, and then adjust the positioning pin on the operation side after positioning with the power side hole. When the plate cylinder is working, ink should be added at any time during printing. When adding ink, attention should be paid to the external dripping and leakage of ink on the printed matter.
2 Install Flexo printing machine anilox roller
Install the anilox roller of the Flexo printing machine with the inking switch turned off. Before positioning the anilox roller of the Flexo printing machine, firstly adjust the repeated alignment between the groove of the rotating coupling shaft and the groove in the sliding block (perpendicular or parallel to the horizontal plane); Tools; pay attention to adjusting, after the position of the anilox roller boss of the Flexo printing machine to the vertical and horizontal grooves, place the positioning, and then turn the anilox roller by hand to check the accuracy of its position and remove the protective layer;
at the same time, pay attention to all Flexo printing Before entering the rough meshing state, the anilox roller, the plate cylinder, and the printing roller gear are all carried out when they are not rotating. When loading and unloading, special attention should be paid to the collision between the surface and the metal surface (due to the material, once the surface of the anilox roller of the Flexo printing machine collides, it is easy to cause permanent damage). In the process of use, the position and equipment of the anilox roller of the Flexo printing machine should be determined according to the quality of the printed parts after proofing and confirmation. (Professionals must strictly check the samples, and use a 50x magnifying glass to determine whether the plate is correct or not; what is the status of the outlets; whether the color and content are in line with the incoming samples; it can be put into production after inspection). The color sequence determines the position of the anilox roller of the Flexo printing machine, so it should be changed frequently and pay attention to safety.
A. Treatment of color sequence:
The quality of printing and varnishing has a lot to do with the color sequence of the printed matter. Correct and reasonable printing color sequence enables the ink to be fully dried from the inside to the outside. If you print bright light on a well-dry print, there will be no problems such as sticking and fading. And make the original printed matter more vivid and lustrous.
Color order arrangement principle:
① Arrange the color sequence according to the degree of transparency of the ink;
② Arrange the color sequence from the convenience of overprinting;
③ Arrange the color sequence according to the original color atmosphere and requirements. If the paper has good printability, first print a large area of base color and light color, then print dark and small color blocks, and finally print bright oil. The glossy layer covers the surface of the colored ink layer, which makes the surface of the ink layer smoother and smoother, and the light reflection changes from the original "diffuse reflection" to "specular reflection", and the color is bright and the texture is full visually.
B. The relationship between Flexo printing machine anilox roller and printing plate and product quality:
Flexo printing machine anilox roller, as the core solar chemistry in Flexo printing machine printing, plays a pivotal role in Flexo printing machine printing, it directly determines the amount of ink The size is related to the quality of printing.
For printing color gradation patterns, text, lines, ink blocks, and halftone images, it is necessary to understand the relationship between the number of anilox lines and the resin printing plate. Five times the cosmetic packaging, otherwise, white dots or incomplete dots will appear on the dots of the pattern, resulting in hue deviation, blurring, and other drawbacks. (The screen roller with more than 700 lines is selected for the printing layer version; the screen roller with 300-400 lines is generally selected for the solid version, and the ink is relatively plump and thick; the screen roller with about 250 lines and 600 lines is suitable for glazing and gold coating) Use Flexo printing machine When the printing machine prints the layered version, the most difficult thing to solve is always the expansion of the dots; the screen roller with a higher number of lines is selected, the ink layer is thinner, and the expansion and deformation of the dots are easier to control.
As the choice of the Flexo printing machine anilox roller for the solid line, text, and other printing plates, it is very important to select the Flexo printing machine anilox roller according to the amount of ink supply. For solid printing, if the number of screen lines of the anilox roller of the Flexo printing machine is too low, the ink supply is too large, and the solid edge of the printing plate accumulates ink and causes ghosting on the edge of the printed product; if the number of screen lines is too high, the ink supply is insufficient, If the solid density is not enough, it will be blurred. If the two solids are superimposed or the printing area is small, you can choose a higher number of screen lines, characters, and line versions. You can choose the appropriate Flexo printing machine anilox roller according to the size of the characters and the thickness of the lines.
Different printing materials have different requirements on the amount of ink Heidelberg, so when choosing the anilox roller of the Flexo printing machine, the ink load should be considered. For non-absorbent printing materials (such as PE, PP, PET aluminum foil, etc.), the number of lines of the anilox roller of the Flexo printing machine should be correspondingly high due to the small amount of ink transfer required; for absorbent materials (such as paper, cardboard, etc.) ), due to the large amount of ink transfer required for cosmetic packaging, the number of anilox lines of the anilox roller of the Flexo printing machine should be correspondingly low.
3 Flexo printing machine plate
Adjust the position of the sliders on both sides of the frame according to the diameter of the printing plate, so that the holes are basically level with the printing roller; then put your hands (no oil stains) on the plate to protect the layout; insert the plate cylinder shaft, and press the pin to set it when inserting. The key can be inserted normally; after insertion, the plate cylinder is moved laterally to make the two enter the mutual pinning state. Roughly check and roughly adjust the horizontal printing position for high-fidelity printing, and check whether it is reasonable and safe; adjust the relative position between the anilox roller and the plate cylinder, the plate cylinder and the printing roller (at this time, the air source should be connected and the pressure should be closed. down), and ensure that the left and right, up and down are parallel, and check with a version gauge (fuel gauge). (The current thickness of the machine is 1.7mm ink, and the thickness of the paste is 0.38mm. Pay attention to the thickness of the two and adjust the thickness of the plate gauge).
A. If the diameter of the plate cylinder needs to be changed, the plate cylinder with the corresponding circumference should be selected according to the size of the printed product. Pay attention to the change of the air tube at the cylinder slider (friction leakage) and the collision of the cylinder shaft.
B. The positioning of the printing plate shaft on the printing plate slider should not have lateral (axial) movement. If so, please adjust the positioning block; at the same time, you should fine-tune the tightness of the circumferential rotation of the handwheel by hand to adjust the opening. The screw shall prevail; the degree should be tight enough to be able to rotate, just slide it. After the printing plate shaft is removed, it should be placed in the positioning area of the printing station.
Note: This part of the operation is the 2nd generation machine, which is different from the 3rd generation machine. Beverage packaging
4 Add ink to the Flexo printing machine
Before adding ink for digital printing, use a damp non-fiber cloth to wipe the entire surface of the anilox roller to clean it;
Before rotating the anilox roller of the Flexo printing machine, add ink (the viscosity and PH value must be guaranteed) to rotate the anilox roller with ink in a small amount, carefully install the scraper, and move it laterally a few times (do not dry grinding on the anilox roller). Or add a squeegee during rotation), the pressure of the squeegee should be appropriate, neither too large nor too small. It is recommended to first adjust the pressure so that there is no ink on the anilox surface (that is, it has been scraped), and then reduce the pressure to make ink appear on the roller surface, and now increase the pressure slightly so that there is no ink on the roller surface and the publishing dynamic occurs.
At this time, it is considered that the pressure adjustment is appropriate. Make sure that the straight line of the knife edge and the axis of the anilox roll are completely parallel (wear gloves when installing and removing the old scraper to prevent the sharp knife edge from being cut). If the pressure is too large, it will affect the life of the anilox roller; if it is too small, it will not be able to achieve its due effect, scrape off the excess ink, reduce the printing color difference DTP, and improve the dot definition. The thinner the ink, the more controllable the printing effect of high-gloss dots can be. Rotate the anilox roller, and pay attention to observe the ink bars caused by the knife edge in the longitudinal direction. If a smooth and even ink layer cannot be obtained, you can check the blade of the squeegee to see if it has physical damage or rust. It may also be that the screws on the fixed squeegee are loose, causing the blade to be in contact with the anilox roller of the Flexo printing machine. The axes are not parallel; in addition, the screws on the doctor blade holder should be carefully adjusted to change the contact pressure between the doctor blade and the surface of the anilox roller of the Flexo printing machine.
(Do not scrap the squeegee with small defects easily, it can be randomly run-in connection processing on other spare Flexo printing machine printing units, and then used after the defects are worn away). A scraper can continue to be used during its life even if it has been ground off a few millimeters in width. Folding can also be adjusted according to the pattern position.
The thickness of the blade can be selected according to the number of lines of the anilox roller. For color overprinting, a Flexo printing machine anilox roller with a high mesh line should be used, and a thinner blade should be selected. , The friction force generated by the rough surface is large, so thicker blades should be selected.
After the scraper blade is cleaned, it should be coated with alcohol to take away the water and keep the blade from rusting and forming a concave notch.
Flexo printing machine The ink ductor roller scraping ink printing device, the amount of ink is determined by the following aspects: Flexo printing machine The tighter the ink ductor roller and the anilox transfer roller are pressed for flexo printing, the less ink is applied; the hardness of the Flexo printing machine ink ductor roller The higher the value, the less the amount of ink applied. If the ink fountain roller of the Flexo printing machine is too soft, even if the ink fountain roller of the Flexo printing machine and the anilox transfer roller are pressed very tightly, the ink cannot be scraped off, resulting in excessive ink volume; The faster the speed, the more ink is applied; the lower the ink viscosity, the less ink is applied.
Printing speed and ink viscosity. When using the Flexo printing machine ink duct roller scraping device, if the printing speed is fast, the force of the ink to push the Flexo printing machine anilox roller and the Flexo printing machine ink duct roller to the outside increases. The higher the viscosity of the ink, the stronger this tendency is. So it is difficult to limit the amount of ink. Therefore, when the printing speed is fast, the viscosity and color of the ink should be reduced, and vice versa, the viscosity of the ink should be increased.
In actual production, when using a printing machine with a squeegee, the relative humidity of the workshop is 60%~70%, and the temperature is about 25 °C; Beirne, if the constant temperature, humidity, and quality cannot be guaranteed, it is difficult to grasp). When the temperature and viscosity of the ink change, the printing quality is also different. To maintain the consistency of the printing quality, it is necessary to keep the ink viscosity consistent.
The original printer must attach great importance to the influence of the ink temperature. It is very important to stabilize the temperature of the ink used in the printing at the temperature of the printing workshop. Otherwise, the ink density will change greatly during the printing process, and the ink temperature will increase and the viscosity will decrease. As a result, the density of the printed product will decrease, and the ink layer will be thin and screened. When it is too low, the amount of ink transfer will be unstable.
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Flexo printing machine printing technology is the first choice for packaging
