Talking about the common gravure printing fault and its treatment

The rotary high-speed gravure printing machine has the characteristics of high production efficiency, rich graphic and textural performance, good sense of layering, and strong three-dimensional effect. It is widely used in large-volume printing, especially in cigarette printing. As a major factor in the composition of gravure - paper, printing plates, ink, any one of the printing environment can not meet the requirements, will produce different printing failures and make production impossible.

I have had more than ten years of experience in printing operations and have carried out some analysis on some of the problems encountered.

One, overprint failure:

1, overprint the overall fluctuations: mostly caused by tension instability. The first is caused by the failure of the equipment tension automatic control system, such as mismatched tension setting, mechanical transmission component damage, PIV gearbox bearing damage, etc.; second, unstable paper tension, such as elliptical deformation of the paper roll, poor rewinding of the paper, or lateral orientation of the paper web. The difference in thickness is too large to cause the paper roll to be loose and tight on one side. Third, the first color group plate or the pressure roller is excessively large.

2. Monochromatic overprint fluctuations: Firstly, the bearing of both ends of the printing plate is damaged; second, the bearing at both ends of the embossing roller is damaged; thirdly, the embossing roller or printing plate jumps too much; and (4) the control system is faulty, such as long time. After the shutdown, the control system parameter setting value is confusing.

Second, ink blocking version (Paste): Ink blocking the formation of a lot of reasons, but mainly due to poor printing ink printing due to poor, such as drying too fast, between the color before and after the ink condensation reaction occurs, ink and printing plate The angles of the screens do not match, and the aqueous ink undergoes acidification and deterioration due to high temperatures.

After the occurrence of plugging phenomenon, the printing plate must be cleaned and replaced with new ink in a timely manner, and the drying speed should be reduced, the pressure of the squeegee should be reduced, and the pressure of the platen roller should be moderately increased; if the blockage is caused by the reaction of the ink between the front and rear colors, The ink of the same manufacturer should be used. If the ink and the printing plate match, change the ink or change the angle of the printing plate.

Third, the paper horizontal shrinkage rate is too large: mainly paper moisture content and the printing environment is not adapted, at this time according to the circumstances, adjust the environment temperature and humidity (temperature between 17C to 24C; humidity between 40% to 70%), If there is no obvious improvement after the adjustment between the environmental minimum and the maximum, the printing plate (according to the paper situation) should be modified, and the format of the printing plate should be gradually shortened from the second color group, and improvement opinions should be proposed to the paper mill.

Fourth, printing wrinkles: When the pressure of the imprinting roller is unbalanced, the paper bearing roller bearing wears or the locking screw is loose, and the printing plate shaft is eccentric, it is easy to produce printing wrinkles. At this time, the printing pressure should be corrected and the relevant parts should be inspected. There should be timely replacement of wear and tear. For the wrinkles caused by the paper ruffles, pre-printing pre-drying equipment will be very effective when the equipment is allowed to fold.

Fifth, the printing leakage point (Phototext spot printing is false): mostly paper roughness is not up to standard, the coating layer drying shrinkage lines, poor ink printability caused. First adjust the viscosity of the ink, or change the ink and increase the press pressure. If there is no obvious improvement, only paper can be changed. Of course, adding a static ink-absorbing device is also a good choice.

Source: Shaanxi Xinmao Engineering Services Co., Ltd.