Corrugated board printing quality - troubleshooting

With the development of social economy and the improvement of people’s living standards, people are paying more and more attention to the perfection of commodity packaging. Corrugated carton packaging has a growing share of the entire product packaging industry with its unique features. The key technology of corrugated cartons lies in the printing of ink and wash. This article talks about how to use the equipment improvement to improve the quality of ink printing.

Printing whitening

Printing luster is the most common and most difficult quality problem in the production of corrugated cartons. The causes are: poor ink absorption properties of the paper; dirty printing plates; paper scraps, dust, etc. on the cardboard. The traditional approach to these problems is to change boxes manually or to increase the frequency of manual printing. These methods will play a certain role in objectively, but the improvement effect after the change of the box is not great, and it is easy to cause the efficiency to drop. The rubbing version will also cause the waste of water, electricity, and labor.

After a long period of observation and analysis, the author believes that in the process of equipment installation, maintenance and management, the key to solving the problem of printing and whitening is dust removal. The main source of dust is generated when a single knife separates paper. Based on this situation, the author installed electrostatic suction and dust collection devices two years after the cross cutting knife of the paperboard production line and the paper feeding section of the printing machine. Before the computer cross cutting knife, the hair dryer was used to separate the single knife. The paper scraps hidden in the pits are blown out or blown off, and then the paper dust is sucked away by an electrostatic suction dust suction device at the delivery rack after the computer crosses the knife. In the paper feeding section of the printing press, the dust on the paperboard is sucked away by the electrostatic dust to keep the printing surface clean and dustless. In this condition, when the paperboard enters the printing roller, ink is applied. Barrier-free, uniform ink absorption. After such improvements, the printing effect of the product has been greatly improved, and the phenomenon of printing and whitening caused by dust has been fundamentally overcome.

Overprint processing

Nowadays, more and more attention has been paid to the artistic and three-dimensional appearance of the patterns in the packaging of goods so that consumers can feel the perfection of the purchased goods from the packaging. To achieve this goal, packaging printing must use multi-color printing, that is, multi-color overlay.

In the overprinting process, there often occurs the overlap between the latter color and the previous color, or the positional position is misplaced, so that the printing pattern cannot reflect the design effect of the product packaging, and even diverges completely, completely destroying the image of the product.

In response to this particular problem, the author's company spent a period of time in-depth investigations and researches on the site, and made detailed calculations on the degree of electronic control response to the accuracy of mechanical fit tolerances. Many improvements were made to the existing equipment and relevant Equipment maintenance measures.

Improve the accuracy of printing drum phase positioning

The phase position of the printing cylinder is controlled by the encoder and counter. If the precision of the counter is too low, the position of the encoder will be inaccurate. Generally counter reflects the speed of 3K, but often results in an error of ±1mm during positioning. After discussions with Taiwan Electric Control Co., Ltd., a 5K counter was produced, which reduced the positioning error of the printing cylinder to ±0.4 mm. Timing lubrication, testing transmission machinery

In the paper feeding process, if the transmission machinery can not maintain a good and smooth operation, the position of each paper board arrives at a change, which will lead to printing and positioning. Therefore, it is very important to perform proper maintenance and inspection on the equipment. A daily commissioning checklist can be developed for daily startup work, including lubrication maintenance. At the same time, the limits for wear of the paper feed roller and paper feed ring should be established. If it fails, it must be worn and re-wrapped or replaced to overcome the phenomenon that the paperboard walks or tilts during walking.

Using suction paper feed

The traditional printing press adopts the upper printing and can only use the paper feeding wheel to convey the paperboard, while the new printing press adopts the advanced technology of lower printing and upper suction air conveying the paperboard. The suction paper feed uses the wind to suck the paperboard on the transfer wheel. The suction force is uniform, no movement, no inclination, and the curved paperboard is leveled and printed. The ink is evener and flatter.

Printing ink bad treatment

Ink problems In addition to paper and offset problems, there are technical problems with the ink roller on the device.

Ink roller are used in the anilox roller, in the high standard; carton printing, using more than 250lpi anilox roller, the mesh is most likely to be blocked by ink residue, resulting in uneven ink, ink is not enough, ink Shallow phenomenon. The traditional method is to use clean water to clean the ink roller. No matter how the water scrubs the ink roller or the scrubbing method, the effect is not ideal. A new ink roller is used for less than a month. The effect is obviously not as good as before.

The author's company, through long-term exploration and experiments, believes that the following methods can effectively solve the problem of poor printing ink.

Add a filter in the ink tank to prevent the ink particles from being transferred to the ink roller.

Regularly (usually two weeks) use an anilox roller cleaner to perform cycle cleaning.

Every day after work, use a dripping circuit to clean the ink roller, and use a 60-times-100x magnifying glass to dial the mesh of the ink roller. There must be no residual ink residue. If any residual ink residue remains, it should be immediately wiped clean with a deep cleaner.

Through the above points of maintenance, the inking ink roller effect can always be maintained.

The above-mentioned several printing technical problems are crucial to the quality of the carton products in actual production. Through the recognition and improvement of the equipment and good maintenance, the products that the customer is satisfied with can be produced and the comprehensive benefits of the enterprise can be improved.

Author/Zhang Yi

<Corrugated carton> June 2005 issue