Screen Printing Common Quality Problems Analysis

Reasons for deviation in printing accuracy

1. When making multi-color overprint (halftone printing) screens, the screens are dried at different temperatures, thereby causing errors in the printing accuracy.

2. The screen has low tension or overprint (halftone) screen tension.

3. Use a simple drying dryer and dry the screen unevenly.

4. The use of too old, unsturdy, and deformed grids to make plates, resulting in deviations in the printed image due to poor stability of the frame (these problems can be detected with negatives)

5. When using multi-color printing, the net distance is not used.

6. Squeegee deformation.

7. Affected by some factors caused by changes in the size of the substrate

Causes of moiré

1. Incorrect matching of halftone printed cable and screen mesh (the number of screens should be 2.5, 3.75 or 6.25 times of the cable).

2. There is an error in the angle between the halftone printing screen and the screen line.

3. The RZ value is too high (should be less than 8).

4. The template is too thick or too thin.

5. Compared with the wire diameter, too small dots will be lost (the dot range should be 5-95%).

Cause of color change

1. The ink consistency changes (different viscosities) due to evaporation of the solvent.

2. Change the squeegee angle during printing.

3. Change the scratch hardness in the printing process.

4. Change the speed during printing.

5. The adhesive edge is damaged.

Causes of premature stencil damage

1. Insufficient rubber.

2. Insufficient drying before exposure.

3. The exposure time is insufficient.

4. The net distance is too high.

5. The ink blade is too dry and the pressure is too high.

6. Use the wrong cleaning solvent for cleaning (including a small amount of water).