If you have any needs pls contact me-
Whatsapp number of Ivy: +852 57463641 (My Wechat +86 18933510459)
Email me: 01@songhongpaper.com
When operating carton printing machines, printed materials may experience color variation after prolonged use. In such cases, most users are often unsure of the root cause and end up spending significant time and resources on repairs. To address this issue, I would like to share several effective strategies that may help resolve the problem efficiently.
First, it is essential to evaluate the layout design of the printed materials. For instance, placing graphics with high ink coverage at the drag area is not conducive to high-quality printing. Instead, positioning them at the gripper area facilitates better paper control and reduces the likelihood of color deviation. After implementing these adjustments, the issue may be resolved. However, if color variation persists, it is advisable to contact the equipment manufacturer for professional maintenance.
Once the printing plate is confirmed to be free of issues, the next step involves inspecting the ink delivery system. A simple method to check for potential problems is to thoroughly clean the ink system using car wash water (with added water if necessary). After the machine is stopped, inspect the ink circuit for the presence of white crystalline particles. If such particles are found, they may be responsible for localized color shifts due to ink buildup. This type of discoloration often manifests as uneven ink distribution across the printed surface.
If no crystalline substances are detected after cleaning, restart the machine and inject ink into each ink roller. After completing the ink injection, close the plate ink roller and plate water roller and verify whether the pressure meets the standard specifications. If not, it is recommended to recalibrate the pressure of all ink rollers to achieve optimal printing performance.
Following these adjustments, a test print should be conducted. It is advisable to use high-quality coated paper to eliminate potential paper-related influences. For thinner paper, set the embossing air volume to a minimum, while for thicker paper, adjust it accordingly. If color variation still occurs, avoid immediately attributing the issue to the printing machine itself. Instead, examine the surrounding components first. Use a magnifying glass to inspect the dots on the printing plate for any signs of deformation. If dot deformation is observed, further examine the film to rule out any issues that may have occurred during the prepress stage.
Fourth, evaluate the paper feeding conditions, including air adjustment, front guide flatness, paper-to-feedboard alignment, and the operation of the paper feeding belt. After confirming that the ink delivery system is functioning properly, inspect the water delivery system. Adjust the pressure between the plate water roller, metering roller, water bucket roller, and water diversion roller, with particular attention to the middle roller. If technical expertise is limited, it is advisable to avoid using the middle water roller during the printing process.
If the color variation issue persists despite all previous measures, inspect the gripper system. Clean the gripper pads and gripper bars thoroughly, preferably after removing the springs. Some manufacturers only clean the gripper pads but neglect the gripper bars, which is not sufficient. Check for any stuck grippers using an effective rust remover such as WD-40, and apply lubricant to the grippers and gripper shafts to ensure smooth operation. If no issues are found in the ink and water systems, inspect the rubber blanket. It is recommended to use a standard 35-micron thick blanket made from a reputable brand with aluminum strips. A new rubber blanket should be retightened after initial use.