Ⅰ. Poor ink drying
1. Reasons: inappropriate ink formula, too low drying temperature, insufficient drying time, etc.
2. Solutions:
1) Adjust the ink formula and select quick-drying ink suitable for PET sheets;
2) Increase the drying temperature, but be careful not to be too high so as not to affect the performance of the sheet;
3) Extend the drying time, which can be achieved by adding drying equipment or adjusting the production line speed.

Ⅱ. Poor ink adhesion
1. Reasons: poor surface treatment of PET sheets, poor compatibility between ink and sheets, improper printing pressure, etc.
2. Solutions:
1) Perform appropriate surface treatment on PET sheets, such as corona treatment, coating treatment agent, etc.
2) Increase surface energy;
3) Select ink with good compatibility with PET sheets, and add adhesion promoter;
4) Adjust printing pressure to ensure that the ink is fully attached to the sheet.

Ⅲ. Inaccurate overprinting
1. Reasons: insufficient precision of printing equipment, deformation of sheets during printing, improper operation, etc.
2.Solution:
1) Regularly check and maintain printing equipment to ensure equipment accuracy;
2) Select PET sheets with good dimensional stability and pre-treat the sheets appropriately before printing;
3) Strengthen operator training, improve operating skills, and ensure accurate overprinting.

Ⅳ. Dot enlargement
1. Reasons: excessive printing pressure, inappropriate ink viscosity, plate quality problems, etc.
2.Solution:
1) Adjust printing pressure to find the appropriate pressure value;
2) Adjust ink viscosity, add diluent or thickener;
3) Check the quality of the plate, and replace the plate in time if there is a problem.

Ⅴ. Color deviation
1. Reasons: inaccurate ink mixing, changes in ink viscosity during printing, uneven printing pressure, etc.
2.Solution:
1) Strictly mix ink according to standard formula;
2) Control ink viscosity to ensure stability during printing;
3) Adjust printing pressure to make the pressure evenly distributed to ensure color consistency.