Scrapers and plate rollers are the most prone to wear and tear in gravure printing, and once they wear and tear, they have a significant impact on the quality of printed matter. Here are some methods to prevent scraper and plate drum wear.
Measures to prevent scraper damage and troubleshooting methods
In gravure printing, although the phenomenon that the Doctor blade is worn into crescent shape in the image and text area is rare, once it occurs, it will lead to scratches or even patches on the printed matter, and the ink will appear strip like paste or adhesion, which will seriously affect the authenticity rate and delay the delivery time. How to prevent blade wear caused by scrapers, printing plates, and ink, and how to solve any malfunctions?
1、 Measures to Prevent Scraper Damage in Gravure Preprinting Equipment
1. Need to shut down for half a day or longer to clean the ink tank. In addition to pouring out the ink and cleaning the ink tank and printing plate, a top cover should also be added above the ink tank to prevent dust from falling in.
2. For positioning scrapers, adding spring pads at the compression shaft cores at both ends can improve the elasticity of the scraper.
3. For a moving scraper, placing rubber or foam plastic pads on both sides of the scraper can reduce hard friction.
2、 Causes of Scraper Wear and Troubleshooting Methods
1. When the scraper is not straight or has signs of damage, it needs to be replaced.
2. If the angle between the scraper and the drum is not suitable, the scraper needs to be corrected.
3. When the drum processing is poor (such as deep pattern or poor aluminum plating material), the printing plate needs to be replaced.
4. The position of the printing plate is not suitable, usually just adjust the printing plate.
5. Ink particles that are large and hard, or have impurities or sand particles, will cause excessive adhesion of the ink to the printing plate. At this time, it is necessary to adjust or replace the ink.
Reasons and Solutions for Excessive Wear of Gravure Plate Drum
Reason 1: Poor quality of chrome plating on printing plates.
Solution: Check the thickness, hardness, and smoothness of the chromium plating layer.
Reason 2: The surface of the gravure printing cylinder is uneven.
Solution: The surface of the printing plate cylinder should be ground, or the gravure plate should be re engraved, or chrome plated again.
Cause 3: There are foreign particles behind the Doctor blade.
Solution: Filter the ink using a filter device that is at least 25 microns in diameter.
Cause 4: The angle and pressure of the Doctor blade are incorrect.
Solution: Check and adjust the setting of the Doctor blade.
Reason 5: There are abrasive pigments in the ink.
Solution: Recombine the ink with less abrasive pigments.
Reason 6: Poor ink grinding effect.
Solution: Replace with a new batch of ink, or regrind ink with unsatisfactory grinding effect.
Reason 7: The ink dries too quickly.
Solution: Reduce the amount of solvent used, reduce the drying speed, or use slow drying solvents to mix ink.
Reason 8: The pH value of the ink fluctuates.
Solution: Maintain the pH value of the ink within a specific range.