Causes
1. Changes in slurry viscosity: At the beginning of printing, the slurry has good fluidity and the scraper can easily cut excess slurry. However, as the water in the paste evaporates, the slurry gradually thickens and the viscosity increases. The scraper needs to increase the force to cut the excess slurry cleanly. The increase in force will cause the screen to deform elastically and cause pattern displacement. After the force of the scraper disappears, the screen rebounds, and the edge of the pattern on the screen printing surface will stick to the slurry. During the second printing, these slurries will move to the edge of the pattern, causing the edge of the pattern to be blurred.
2. Screen elasticity problem: The screen is too elastic, and the rebound force is large after the force of the scraper disappears, which makes it easy for the edge of the pattern to stick to the slurry, resulting in blurred edges.
3. Insufficient screen tension: Insufficient screen tension will affect the cutting effect of the scraper on the slurry, resulting in the edge of the pattern not being clearly presented.
4. The viscosity of the slurry is not adjusted in time: During the printing process, if the viscosity of the slurry is not adjusted in time, it will make it difficult for the scraper to cut the slurry, which will affect the clarity of the pattern edge.
Solution
1. Use a screen with low elasticity: Choose a screen with low elasticity, such as a polyester screen, to reduce the elastic deformation of the screen and reduce the possibility of the pattern edge sticking to the slurry, thereby effectively improving the problem of blurred pattern edges.
2. Increase the tension of the screen: By adjusting the tension of the screen to a suitable level, the cutting effect of the scraper on the slurry can be improved, making the pattern edge clearer.
3. Reduce the resilience of the screen: Take measures to reduce the resilience of the screen, such as using special screen materials or adjusting the installation method of the screen, which will help reduce the situation of the pattern edge sticking to the slurry, thereby improving the clarity of the pattern.
4. Adjust the slurry viscosity at any time: During the printing process, pay close attention to the changes in the slurry viscosity, and make timely adjustments according to the actual situation to maintain the appropriate fluidity of the slurry so that the scraper can smoothly cut off the excess slurry and ensure the clarity of the pattern edge.
