The root cause of corrugated board printing problems (below)

The causes of the specific printing problems and their solutions After analyzing various aspects related to the quality of printing, based on my own experience, the author put forward some reasons for the following problems encountered in printing:

Insufficient ink is due to ink pump being too slow or inoperative, ink path leaking, anilox or rubber roller bearing or transmission abnormal, anilox roller and rubber roller gap too small, and anilox roller and print roller gap too large Or the anilox roller is not in place. The printing color is too light because the viscosity of the ink is too low, the anilox roller is partially blocked, the printing plate is aged, and the gap between the anilox roller and the rubber roller is too small. The connection between dirty or ink dots on the printing surface is due to water marks and debris on the printing plate;
Corrugated cardboard with dry paper or glue pieces;
Inadequate production or design of the printing plate dot network causes the connection of the dots; the viscosity of the ink is too high; the gap between the anilox roller and the printing roller is too small;
The gap between the anilox roller and the rubber roller is too large;
When two or more colors are overprinted, the unprinted portion of the printing plate is pressed against the surface of the corrugated cardboard; the ink is not dried; the printing plate is not taut on the printing roller or the printing plate is degummed; the printing is performed using a squeegee device.

Imprinting is not uniform because the printing plate is not clean; the anilox roller is partially blocked; the anilox roller or rubber roller (scraper) is worn and damaged;
There is debris between the anilox roller and the rubber roller (scraper); the surface of the printing roller or the embossing roller is not even; the paper feeding roller is worn, and some of the corrugations are crushed;
Plates are different. Ink frothing is due to too many ink cycles; the ink needs to be adjusted. Imprinted holes or fish-eye holes are due to too much ink foam, poor flatness on corrugated paperboard (noodles), small holes in the plate, and too much defoamer. The stencil-like imprinting is due to the low basis weight of corrugated cardboard, and the poor control of corrugated cardboard.
The hardness of the plate is low; the feed roller gap is too small and the corrugations are crushed; the gap between the embossing roller and the printing roller is too small. Halo is due to the high viscosity of the ink;
The gap between the anilox roller and the printing roller is too small;
Under different network lines, the gray scales that are prone to halos are different. According to the conditions of the anilox rollers, the rules are summarized, and the layouts are designed to avoid as much as possible. Tilting of the printing (inclination of the printed writing or pattern relative to the position of the entire board) is due to the feed tilt;
Pulling roller (non-vacuum conveying) gap is not set well; corrugated board warping is serious; no pressurizing strips are installed on both ends of the printing plate (must be in contact with the cardboard).

The lack of ink on the blot is due to the unevenness of the plate installed on the printing roller; the damage of the plate; the dry ink layer on the plate; the height of the cardboard surface; the ink drying is too fast. Imprinting ink between the gaps is due to the printing plate is not scrubbed clean; poor ink re-dissolve, adjust the ink, it is recommended to use high-concentration low-viscosity ink; anilox roller and the printing roller gap is too small; ink drying too fast plate dirty; The ink is added to the gap; the hardness of the plate is small; the particles in the ink are agglomerated.

Imprinting is not clean because the ink dries slowly; the pull roller position is not good. The poor quality of overprinting is due to the fact that the overprinting effect is mainly caused by the overprinting of the overprinted ink, which is also a weakness of the water based ink printing, and can be improved by improving the performance of the ink. For example, use fast drying resin to formulate ink or add quick drying agent to ink; color sequence should be from light to dark, ink viscosity should be from low to high, ink PH value should be from low to high; printing speed should be reduced; The printing units that need to be stacked can be properly spaced at a longer interval; infrared drying or blowing of the running cardboard can be performed.

The uneven coverage of ink is due to the fact that the surface of the corrugated paperboard is not sufficiently smooth; the feed roller is worn and both ends of the corrugated board are collapsed;
Anilox roller part of the network plug; rubber roller surface is not even; anilox roller and rubber roller is not parallel;
The anilox roller is not parallel to the printing roller during printing. Ink density and brightness are not standard due to ink formulation problems;
The ink viscosity is irrational;
The speed is different from the proofing; the difference between the anilox roller and the rubber roller is different from the proofing; the color of the corrugated paper is different; the printing machine used is different;
Plate changes. The corrugation is crushed during printing because the feed roller gap is too small;
The gap between the embossing roller and the printing roller is too small;
The corrugated board has too low compressive strength; the plate has a high hardness. Improper overprinting is due to the fact that the printing plate design is not scaled up and down; the layout of the printing plate is inaccurate; the printing plate is not taut at the printing press; the press plate is not installed at both ends of the printing plate (must be in contact with the paperboard);
Corrugated board warping;
Pull roller position or gap is not set properly;

The difference between the old and new pads on the printing roller causes the plate to be stretched differently; the diameter of the printing roller is different. Distorted printed writing or images (printed handwriting or image distortion that does not meet the printing requirements) are due to inaccurate layout of the printing plate, and sticking of the double-sided adhesive on the printing plate does not work.

The blurring of the printed writing and the fuzzy imprinting are due to the fact that the gap between the anilox roller and the printing roller is too small, and the anilox roller will deform the upper part of the printing plate when touching the printing plate. The printing shows the ghosting on the top of the font or color block;

If the gap between the embossing roller and the printing roller is too small, the printing plate will be excessively stretched, the lower plate will be deformed, and the printing will appear as a ghost or an upper part of the color block;
The corrugated board is shaken when it is driven in the printing machine, resulting in the fuzzy outline of printed writing;
Cardboard warpage, printing plate can not be in smooth contact with the paper version; press vibration, equipment operation is not balanced. It is prone to occur when processing full die cut products.

Author/Niu Shengfeng

Source: Corrugated carton