Web Gravure Not Allowed for Horizontal Overprint

In gravure gravure printing, the contact of the paper with ink (especially aqueous ink) causes the paper to shrink laterally, resulting in misalignment of the paper. Solving this problem has become a major problem for web gravure printing. This paper, combined with practical experience in the production of web gravure printing, elaborates on the causes and control of horizontal overprint inaccuracy from the following aspects.

1. The moisture content of the paper is related to its moisture content. The different moisture content of each part of the paper roll before printing will cause different shrinkage after printing, resulting in inaccurate horizontal overprint. The solution is to install a preheating oven on the printing machine before printing, and try to make the water content of the paper consistent before printing.

2. Platemaking According to practical experience, horizontal shrinkage should be reserved when making plate, so that the actual shrinkage of the plate and the paper is consistent.

3. Rolling paper produced by manufacturers of different webs tends to have inconsistent transverse shrinkage, and it is best to use webs made by the same manufacturer for the same set.

4. The moisture content of the ink varies with the moisture content of the ink, resulting in different shrinkage of the paper. Therefore, the water content of the ink should be controlled so that the water content and viscosity of each color ink are consistent.

5. Drying box temperature The drying box temperature is different, it will cause the evaporation rate of the paper to be different, resulting in different transverse contraction rate. In the actual operation, the temperature of the oven should be kept the same at each printing. According to the size of the actual horizontal overprint error, the oven temperature can be appropriately increased or decreased.

6. The gravure printing machine gravure printing machine has low mechanical precision, such as the error of the guide roller parallelism is too large, the precision of the transmission gear is not enough, etc., which often causes the paper to swing laterally in the printing process, resulting in inaccurate lateral overprinting.

During the printing process, due to the instability of the gravure printing machine system, such as the magnetic powder brake aging caused by tension fluctuations, or due to the release paper clamping plug, the paper roll slipping tension can not be controlled, resulting in the paper overprinting is not allowed.

7. Roll paper roll The paper roll is not neat or the thickness of the paper is uneven, causing the paper to oscillate laterally from side to side during printing, resulting in misalignment of the paper.

Author: Yang Zhengxiong

Reprinted from: "Printing Technology"