Gravure Plate Failure Analysis and Troubleshooting: Inaccurate or Excessive Inking

(I) Paper flatness factor

Ideally, both sides of the paper should be smooth, flat, and uniform in thickness so that it can make good contact with the flat surface of the contact (such as liners, blankets, plates, etc.). However, in reality, most papers are not ideal. They are mainly characterized by: uneven thickness, undulating paper, and only one side of the printing plate; the surface of the paper is rough and can only be discontinuous with a small area of ​​the printing plate. Contact is one of the factors that cause paper to be inaccurate.

In general, paper with a undulating surface but a uniform thickness can be brought into good contact with the printing plate by adjusting the printing pressure. However, if the unevenness of the paper is poor, it cannot be adjusted in this way. However, if the paper is flat on one side, it can be lined with a cushion to make good contact with the plate. However, both methods cause the paper itself to stretch or bend, and the pressure required is adjusted according to the amplitude, frequency, unevenness of the paper surface, and the hardness of the paper.

(II) Factors of different ink receptivity on paper surface

The papers currently used are coated paper, white cardboard, gold cards, silver cards, and glass paper cards. At the same time, gold cards and silver cards also have aluminum foil gold cards, silver cards, and multiple PE film gold cards and silver cards.

In addition to the flatness of the paper has an impact on the printing ink, but more importantly, the amount of ink itself is also the main factor. For example, compared with gold and silver cards, white card paper absorbs ink more than gold and silver cards. However, the amount of ink absorbed by the former gold foil or silver foil of the aluminum foil and the gold foil and silver foil of the double PE film is significantly greater than that of the latter.

Due to the above factors of paper, the customer should provide accurate paper information at the time of plate making, so that the platemaking company can make different platemaking processes according to different paper properties.

(III) Problems in Information Transmission

In the printing process, paper, ink, platen rollers, and printers are all suppliers to the printing factory. A high-quality product must be the best match for them. No matter what problems occur at that stage, they must produce defective products. Therefore, the cooperation and exchanges between the Quartet are very important. However, in the actual work, due to the large industry span and the few opportunities for mutual exchanges, it is very difficult to rely solely on unilateral settlement when there are comprehensive problems in printing. For example, when the company is making a soft package for a customer, one of the large red blank words (English words, Chinese will be even worse), and the printed blank words after printing will be significantly thinner than the sample. Look at our company's concave blank text is slightly more coarse than the sample. We analyzed with customers and tried to solve the problem by increasing the viscosity of ink and reducing the printing pressure. The phenomenon of ink bounce after printing was obvious. This phenomenon was eliminated after the ink formulation was replaced again.

Another problem, due to a variety of factors, many manufacturers are eager to deepen the depth of the plate, so that the plate almost reached the limit of the depth of electronic engraving. In fact, the deeper the printing roller is, the more unfavorable it is for high-speed printing, and the easier it is to produce knife wire, jamming, and dragging ink on the edge of the pattern.