In the world of water-based ink printing, achieving an exceptional final product requires more than just the expertise of the press operator. Success depends on multiple factors including equipment, raw materials (such as cardboard), water-based inks, printing plates, templates, the working environment, and effective team management. Only when all of these elements meet high standards can the risks that affect print quality be minimized.
Of course, a press operator’s ability to handle unexpected issues is equally important. This skill comes with experience, as operators learn to identify and resolve problems by understanding their root causes. The key to improving both print quality and operational efficiency is analyzing the problems encountered and developing practical solutions.
In this article, we will focus on one common issue in water-based ink printing:Â screen clogging, which affects the clarity and quality of printed materials. Here, we will discuss the causes of this issue and explore practical solutions from the perspective of a press operator.
- High Ink Viscosity One of the primary causes of screen clogging is high ink viscosity. When the ink is too thick, its flow becomes restricted. This can lead to the ink quickly filling and adhering to the screen’s gaps upon contact with the printing plate, causing blockages.
- Ink Drying Speed (Too Fast or Too Slow)Â Both excessively fast and slow ink drying times can negatively impact ink transfer. If the ink dries too quickly, it might not transfer evenly, leading to clogged screens. Conversely, if the ink dries too slowly, it can affect how much ink is transferred and how quickly, which also contributes to clogging.
- Incorrect Pressure Settings Pressure settings are crucial for print quality. Whether it’s the impression pressure, plate pressure, or blade pressure, improper adjustment can increase the contact area between the ink and the printing plate. Excessive pressure can alter the angle of contact, leading to poor ink transfer and clogging.
- Mismatch Between Anilox Roller and Screen Line Counts The optimal ratio between the screen line count and the anilox roller line count is typically between 1:4.5 and 1:5. If the ratio is too far off, controlling dot gain becomes difficult, leading to screen clogging during the printing process.
Practical Solutions for Screen Clogging
- Adjusting Ink Viscosity and Drying Speed It’s essential to adjust the ink’s viscosity and drying speed according to the machine’s production speed. Faster production speeds require quicker-drying inks, while slower speeds necessitate inks with slower drying times. Finding the right balance is key to preventing clogging.
- Fine-Tuning Printing Pressure Proper pressure adjustment is critical for achieving high-quality prints. Ensure that the impression, plate, and blade pressures are all set appropriately—neither too light nor too heavy. This balance is essential to maintaining ink transfer efficiency and avoiding screen clogging.
- Reproducing Printing Plates to Match Anilox Roller Line Counts When creating new printing plates, it’s important to set the screen line count based on the anilox roller’s line count. Keeping the ratio between 1:4.5 and 1:5 ensures smooth ink transfer and reduces the likelihood of dot gain, which leads to clogging.
Conclusion
Water-based ink printing is a delicate process that requires constant attention to detail, from ink formulation to pressure settings and plate design. By understanding the common causes of screen clogging—such as high ink viscosity, inappropriate drying speeds, incorrect pressure, and mismatched line counts—press operators can take preventative measures to ensure smooth, high-quality prints.
Ultimately, the key to success lies in a combination of skill, experience, and a deep understanding of the factors that influence print quality. Operators who are able to analyze issues and implement effective solutions will be better equipped to produce superior results, reduce downtime, and meet the demands of modern carton printing.
By:
Moss (Carton Making Machine Flexo Printer Slotter FFG)
