Reasons and Measures for Poor Color Registration Accuracy in Gravure Printing

In the gravure printing process, the inability to accurately register each color sequence often leads to color discrepancies, line shadowing, and other printing defects, which primarily relate to the issue of color registration accuracy. The control of registration accuracy mainly involves both vertical and horizontal aspects, as detailed below:

Tension Variations During Film Traction Leading to Inaccurate Vertical Registration Main reasons include:

1. Improper adjustment of the brake on the unwind unit.

• Excessive material on the roll or an oversized roll diameter causing tension fluctuations.
• Improper speed settings of the three rollers.
• Reduced friction on the surfaces of the three rollers.
• Instability of tension on the rewinder.

Solutions: Inspect the five areas mentioned above and make appropriate adjustments.

2. Poor Diameter Difference of the Printing Cylinder Leading to Inaccurate Vertical Registration The main reason is inaccurate testing of the growth of the diameter difference during plate making. The solution is to remeasure the growth and remake the plate.

3. Abnormal Guide Lines Causing Recognition Interference and Inaccurate Vertical Registration The main reason is insufficient density. Solutions include adjusting the sensitivity of the photoelectric tube or manually eliminating issues such as plate smudging.

4. Small Diameter of the Printing Cylinder Making Vertical Accuracy Difficult to Control The main reason is that the roller diameter is too small. A possible solution is to use a splicing method to increase the roller diameter.

5. Abnormal Horizontal Registration Device Causing Horizontal Deviation Main reasons include:

• Relaxation of the film, leading to poor roller parallelism.
• Uneven printing pressure from side to side.
• Taper formation on the printing cylinder.
• Fluctuations in film tension causing lateral swaying.

Solutions: Inspect all elements and repair the horizontal registration device.