After winding, the ink layer is attached to other contact surfaces (usually the reverse side of the original film) in the form of a sheet or a line.
1. The ink volume is too large, the drying efficiency of the equipment cannot keep up
2. The wrong solvent or the wrong solvent ratio causes the ink to dry too slowly
3. Insufficient drying capacity
4. Excessive winding tension
5. The winding diameter is too large
6. The difference in the depth of the printing plate dots is too large, some places are blank, and there are no graphics or text; in some places, the graphic and text dots are too deep, which causes vertical violent tendons in the deep parts of the dots after rolling.
7. The temperature at the winding is too high
8. Abnormal pressure from outside
9. Ink cohesion is insufficient
Reduce the amount of ink properly
2. Use appropriate solvent or correct solvent ratio
3. Properly increase the drying temperature of the oven (but not too high, otherwise the surface of the printing ink is skinned and it is more prone to adhesion if it is not dried in the middle)
4. Appropriately reduce the winding tension, pay attention to the tightness of the curl when printing, especially the nylon film.
5. For orders that are easy to stick when the roll diameter is large, do not cut large rolls, try to cut small rolls to produce
6. Add a swinging device at the rewinding place, swinging left and right from time to time, making the dots particularly deep and easy to bulge tendons to cross the blank text and text
7. Reduce the temperature at the winding place appropriately and increase ventilation
8. Eliminate external abnormal pressure: semi-finished printed products should not be placed vertically or horizontally; they should be scattered and not overly concentrated when placed. For some special orders, hold it by hand when unrolling, without unrolling
9. Ink with metal powder (such as gold ink, silver ink) is weak in cohesion and sometimes causes adhesion due to a small amount of external pressure. Under the premise of not affecting the coloring effect, appropriately add a toner (also called a diluent)
It should be distinguished from Article 10, which is “lack of ink”, Article 11, which is “missing”, and Article 18, which is “sticky”.
Ink shortage and dot loss: It is an abnormality that occurs when the printing film leaves the impression cylinder of the unit during the printing process;
Sticky ink: The printing film is normal when it leaves the impression cylinder of the unit, but it is abnormal when it passes through the unit's oven, cooling roller, or the other unit's cooling roller;
Adhesion: It is still normal when the printing process is completed, which is called a roll film, but the process (such as inspection, compound) production only occurs after the roll is put into operation. Literally, it seems to be the lack of ink, but the cause is completely different.
廿 2. Ink pollution (referred to as oil pollution)
The non-graphic parts of the printing plate have the phenomenon that the ink adheres to become foggy smear, which is generally manifested as dark stains in blank spaces or light-colored graphics.
In actual production, oil pollution is not very serious every time. If you have to wait until the next roll to find the abnormal oil, then the defective product has been produced. We can look ahead (observe the color of the end face of the roll) to predict and prevent in advance.
1. Squeegee wear or grinding is poor, pressure is low, improper angle causes printing plate ink scraping efficiency is low
2. Ink viscosity is high
3. Printing ink abnormality (contains coarse particles, impurities and printing ink formula defects)
4. Poor plating of printing plate
1. Regrind or replace the squeegee. The harder the squeegee material, the greater the pressure, and the greater the angle.
2. The printing ink should be printed with the lowest viscosity as possible, and new ink can be added appropriately. In addition, it is more effective to add a quick-drying solvent and add a plate blower on the back of the printing plate.
3. If the scraper, pressure, angle, and printing ink viscosity are normal and there is still significant pollution, it is likely that the printing ink is defective. Replace the ink of another supplier and discuss with the printing ink manufacturer to improve.
4. Sand the surface with sandpaper. If the plate is severely defective, it should be remade.
Thirty-three, version injury
As the name suggests, the plate was bruised or stung. Its phenomenon is exactly the opposite of lack of ink. Insufficient ink is missing in the place where there should be pictures and texts, while injured version is where there was no pictures and texts. Assuming that there are nine identical layouts in one edition week, the edition damage usually only appears in one of the layouts. Even if it sometimes appears on two or three layouts, it is just a number of layout injuries that are different from each other, and their shapes and positions can never be exactly the same.
Bumps during printing plate storage
2. Injuries during printing plate transportation
3. Injuries during plate loading and unloading
4. Stabbed by hard foreign objects (such as dropped screws) during printing
5. Stuck by a hard foreign body in the washing machine during cleaning
1. During storage, pay attention to the surrounding environment (such as pallets) for hard debris such as iron nails that may cause plate injuries.
2. During transportation (including plate factory delivery and workshop turnover), handle it carefully to prevent it from falling and being injured.
3. Install the plate before loading the machine and unload the plate at the end of the order. Be careful to handle it carefully. When entering or leaving the unit, guard it with your hands to prevent the edges of the printing equipment from hurting the plate.
4. Standby replacement
5. Some powerful printing plants have plate washing machines (also known as plate cleaning machines), which use plate washing machines to clean the plates. In the process of cleaning the plate, the hard debris that had previously fallen into the washing machine caused high-pressure rinsing when the plate was washed.
The above three are preventive measures. For printing plates where plate damage has occurred, if the location of the plate damage is outside the effective graphics and text, or even outside the original film width, you can continue to produce normally without paying attention to it. If the location of the plate damage is within the valid graphics, which will affect the aesthetics of the product packaging, there are the following countermeasures:
1. Very minor plate damage: For printing machines with plate blowers, you can turn on the plate blowers at the corresponding parts of the plate blowers; for printers without plate blowers, you can use a leather tube to blow air, and blow the hair to the plate wounds. The wound cannot be printed. If there are printed shallow mesh outlets around the location of the plate injury, you can't blow the air to avoid plugging the shallow mesh after blowing, and you can replace the production version. If it is not available, please ask whether it is produced?
2. Minor plate damage: Before stopping, or before the printing plate is put on the machine, use 400-grit sandpaper to wrap the details of the bamboo stick, oil pen, or marker pen, and sharpen the damaged part of the plate, and then polish with 1000-grit sandpaper. Generally Can reduce the range of plate damage, making it not obvious printing. If there are printing screen dots around the location of the plate damage, you can't grind the plate to avoid the dots being pinched, and you can replace the production version. If it is not available, please ask whether it is produced?
3. Moderate and severe plate injuries: Generally, there will be no obvious improvement after tracheal blowing and plate processing. Replace the spare plate directly. If there is no backup version, it will be replaced for production.
廿 Uneven background
Large areas of spot color appear irregular spots or pits of varying shades.
Generally, the background color of layered transitions is prone to uneven ink scratches, while the pits often appear on the background color of layerless transitions. Therefore, the background color unevenness can be divided into: background color ink scraping unevenness and background color pitting.
(A), uneven background shaving
High ink viscosity
2. Poor ink flow
3. The paper on the back of the scraper frame is too long, resulting in reduced ink fluidity
4. Too much ink left
5. The scraper is not installed flat, and there is a wavy undulating gap with the liner
6. Slight blockage at printing outlets
1. Reduce ink viscosity appropriately
2. Replace the ink with good fluidity
3. Check if the printing plate is too close to the bottom of the ink tank? Is the back stop curled up and hindered the ink flow? Should be improved appropriately
4. Replace with new ink
5. Check if there is any foreign matter between the scraper and the lining knife, reinstall the scraper after removing it, and replace it with a new one if necessary.
6. Wipe the plate vigorously with a foreign matter-free cloth dipped in ink, so that all the printing dots are printed. (Note: You can also use solvents or decontamination powder to erase the plate. Therefore, it is necessary to mark the strip to facilitate the removal of the inspection product. Generally, the use of solvents or decontamination powder is not recommended during the printing process.)
(Two) background pitting
Ink viscosity is too low
2. Printing speed is too slow
3. Press hardness is too low
4. The scraper is too flat (the angle is too small)
5. The printing plate dot is too deep (very small probability)
1. Properly increase ink viscosity
2. Properly increase printing speed
3. Replace the harder press
4. Increase the scraper angle
廿 5. Static glitch
Irregular burrs appear on the edges of the pattern, resembling poor beard-like appearance. In mild cases, the edges of printed images and flowers bloom into beard-like and streaked ink, which will damage the image of the images. In severe cases, sparks may cause fires.
Improper or damaged electrostatic brush
2. If there is static electricity when printing the original film with anti-static treatment, it is mostly meteorological reason: the humidity in the workshop is low
3. The original film used for printing has a high resistance and generates static electricity when it comes into contact with the running guide roller and plate.
4. Bad ink
1. Adjust the electrostatic brush to a suitable position, or repair the damaged electrostatic brush
2. Use a humidifier to increase the humidity in the workshop. (In the actual printing process, you can also use a metal bar or a metal wire to ground the static electricity)
3. Adding electrostatic brush with grounding device can eliminate the static electricity of the original film.
4. Adding antistatic agent to printing ink is also effective for removing static electricity. (Note: Do not add too much antistatic chemical agent, otherwise printing ink sticking phenomenon may occur)