1. Equipment maintenance standards
1.1 Maintenance of the main engine operation system: maintenance includes cleaning and lubrication. Fill the film guide roller and the bearings, sliders, chains, and handwheels that work at room temperature with oil every Monday. Add butter (grease once) to the inner guide roller bearing and chain of the drying tunnel every month and month.
1.2 Maintenance of electrical equipment: including the implementation of electrical control department level, electrical appliances should be kept clean and dry at all times, and the wiring is safe and reliable. It is not allowed to easily fold any electrical equipment.
1.3 Check the whole part of the machine regularly every month and month to see if there are any loose screws and reinforce the loose parts.
Problem solving: (Common faults and solutions for gravure printing)
2. Plate contamination (dragging ink)
2.1 Phenomenon: The ink that has not been scraped by the squeegee is left on the non-graphic part of the plate cylinder, which is transferred to the film during printing and becomes a smudge.
2.2 Solutions
2.2.1 Reduce the printing speed.
2.2.2 Adjust the angle of the doctor blade to make it steeper.
2.2.3 Reduce ink viscosity.
2.2.4 Adjust the solvent to increase the ink drying speed.
2.2.5 Check whether the squeegee is installed straight and the pressure is even.
3. Squeegee marks (cut wire)
3.1 Phenomenon: The ink that has not been cleaned by the doctor blade is dragged into a linear stain on the non-graphic part of the plate cylinder and transferred to the film, which also refers to the phenomenon caused by the lack of the doctor blade.
3.2 Solution:
3.2.1 Filter inks to reduce ink waste and large pigment particles.
3.2.2 Lift the ink knife or use chopsticks to remove the garbage or large pigment particles under the knife.
3.2.3 Check whether there is a small gap in the blade of the doctor blade, and grind or replace with sandpaper.
3.2.4 The surface of the roller is rough and polished with sandpaper.
4. Backprint
4.1 Phenomenon: The ink of the previous color is reverse printed on the printing plate of the latter color.
4.2 Solution
4.2.1 Reduce the pressure of the impression cylinder.
4.2.2 Improve the adhesion of the previous color ink and increase the drying speed of the ink.
4.2.3 Reduce the viscosity of the latter color.
5. Water streak
5.1 Phenomenon: Ink shows uneven printing transfer marks.
5.2 Solution:
5.2.1 Reduce the depth of the cylinder of the printing plate cylinder.
5.2.2 Improve printing speed.
5.2.3 Change the angle of the plate cylinder on the net hole.
5.2.4 Increase ink viscosity.
5.2.5 Correct the printing tension.
6. Block version
6.1 Phenomenon:
6.1.1 During the printing process, the printing ink transfer rate is continuously decreasing.
6.1.2 The ink clogged in the plate cannot be dissolved when production is restarted after printing is completed.
6.2 Solution
6.2.1 The squeegee is placed flat.
6.2.2 Reduce the evaporation rate of the solvent.
6.2.3 Reduce ink viscosity.
6.2.4 The plate cylinder should be clear and clean immediately after each printing. [next]
7. Anti-stick
7.1 Phenomenon: Take up immediately after printing, the ink and the film adhere to each other, or the ink gets on the reverse side of another film.
7.2 Solution
7.2.1 Reduce the winding tension.
7.2.2 Allow the ink to dry sufficiently.
7.2.3 Improve the drying speed of the ink.
7.2.4 Appropriate use of anti-sticking agents.
8. Automatization
8.1 Phenomenon: The ink layer after printing shows self-chemical phenomenon.
8.2 Solution
8.2.1 Reduce the air temperature in the workshop.
8.2.2 Improving the drying capacity of the printing press, drying quickly and thoroughly.
9. Rubber roller garbage
9.1 Phenomenon: There is a regular phenomenon of incomplete printing of graphics and text in printing.
9.2 Solution
9.2.1 Check if there is small garbage such as small film on the rubber roller.
9.2.2 Check whether the surface of the rubber roller is damaged.
10. Color difference
10.1 phenomenon; during printing, the color difference between rolls and rolls occurs.
10.2 Solution
10.2.1 Strictly control the viscosity of the ink and keep it stable and consistent.
10.2.2 Ensure that the ink mix ratio is consistent every time and the color is stable.
10.2.3 Prevent chromatic aberration caused by blocked version of the gradation version.
10.2.4 The printing speed is stable.
10.2.5 The angle of the doctor blade is stable.
10.2.6 Prevent chromatic aberration caused by improper use of old ink.
11. Overprint is not allowed
11.1 Phenomenon: The vertical or horizontal position of the printed matter is misaligned, which makes the printed matter's picture and text blurred.
11.2 Solution
11.2.1 To prevent inaccurate overprint caused by improper gravitation setting, it can be adjusted appropriately according to the actual situation.
11.2.2 To prevent overprinting caused by dirty guide rollers, clean the guide rollers of each unit.
11.2.3 Adjust the horizontal direction at any time.
11.2.4 Check whether the printing plate cylinder and rubber roller jump.
11.2.5 Caused by the quality problem of the film (such as elastic side bell, etc.), replace the film. [next]
12. Size deviation
12.1 Phenomenon: The printed product after printing is inconsistent with the actual required size.
12.2 Solution
12.2.1 Adjust the printing tension appropriately.
12.2.2 Prevent size deviation caused by improper temperature setting.
13. Process operation steps:
The operation of the coating gravure process is as follows:
13.1 Preparation of raw materials. After receiving the production engineering order, according to product specifications, quantity, receive raw materials. According to the color sample of the product, prepare the matching performance ink and the appropriate amount of auxiliary agent. The type and quantity of ink should be adjusted before printing.
13.2 For the installation of the plate roller, select the correct plate and roll it according to the requirements of the process sheet. If printing multi-color products, it is also necessary to pay attention to the left and right sides of the plate roller, and install the printing roller in each unit according to the printing color sequence.
The color sequence of "surface printing" color printing is generally: white → yellow → red → cyan → black.
The color sequence of "Liyin" color printing is generally: black → cyan → red → yellow → white.
13.3 Select the rubber roller that matches the plate roller and install the doctor blade.
13.4 Trial printing after starting up. At a slow speed, open the machine for trial operation to check whether the various parts of the machine are normal, install the roll material on the unwinding shaft, pay attention to make the film processing face the printing surface, and adjust the tension. Check whether the squeegee can scrape the ink evenly without the pattern and whether it is clean.
13.4.1 Drying temperature adjustment, the drying speed of the ink is mainly determined by the temperature of the hot air in the oven in addition to the volatilization speed of the solvent itself. Generally speaking, the machine speed is fast, the ink layer is thick, and the ambient temperature is low. When the humidity is high and the solvent evaporation rate is slow, the drying temperature should be adjusted slightly higher. The principle of temperature adjustment is that the drying temperature is as low as possible on the premise of ensuring that the printed matter is sufficiently dried.
13. 4.2 Adjustment of printing pressure. The printing pressure is generated between the impression cylinder and the printing cylinder. The magnitude of the pressure is based on the ability to produce clear graphics.
13. 4. 3 Tension adjustment. Tension adjustment should consider the following factors:
13. 4. 4 The type and expansion rate of the film, for example, the BOPP expansion rate is large, the tension should be smaller; the PE expansion rate is small, the tension should be appropriately increased.
13. 4.5 The thickness and quality of the film. When the film is thicker, the tension can be increased appropriately; when the tension on both sides of the film is inconsistent, the tension can be increased appropriately.
13. 4. 6 oven temperature. When the ambient temperature increases, the film is easy to stretch, and the tension can be reduced accordingly.
14. Official boot
18.1 Rewinding should not be too tight to prevent product deformation and stickiness. Generally, the product does not slide when the product is wound neatly and vertically.
18.2 Inspection of product quality. (Compared with product quality standards)
The ink on the non-graphic part of the printing plate cylinder is left unscraped by the squeegee, which is transferred to the film during printing and becomes smudge.
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