Reasons and solutions for the occurrence of ink chipping in offset printing

How to reduce the failure rate of printing to the lowest level of connection processing is a topic of concern for every printing company. In this issue of the "Printing Technology" national prize essay contest section featured an article to address the problem of offset printing ink chip failure, the author of the analysis of the clear ideas when the failure, as well as careful summing up the method of troubleshooting experience is worth learning. Digital Publishing

In the case of ink-chip failure, it is because during the printing process, some substances stick to the plate or blanket, and the surrounding area is squeezed and deformed, resulting in ink that cannot be printed on the area. Thus, the center ink dot is dark and the surrounding edges are white. A type of printing fault book printing usually occurs when printing on the ground. Offset is the most susceptible to ink chip failure compared to other printing methods. This is because the ink layer of the offset printing is the thinnest, and when the plate and the blanket are stuck with foreign matter, the flowing ink cannot carry away the foreign matter and easily generate the ink. While the other printing methods print thicker ink layers, it is easy to take away or cover up foreign objects.

The author now combines many years of teaching experience and practice summary, will cause the various factors and solutions of ink crumbs to sum up for readers reference.

Ink blotches caused by ink and ink

Cause: The ink has been placed for a long time, especially for unsealed inks or new ink maps printed in old boxes. Before printing, the dry ink on the surface of the ink or the ink cartridge is not removed, but these inks are printed. The ink sheet can be easily transferred to the printing plate or the blanket, thereby generating toner failure. book review

Solution: 1 If there are more ink skins and there are more ink particles in the print, the ink should be replaced. 2 If there is a small amount of ink in the ink, the small ink fountain gap can be adjusted, and the ink fountain roller rotation angle can be increased. In the premise of not affecting the ink supply, the ink stick is stuck in the ink fountain, so as to achieve the effect of controlling the ink chip failure.

Paper powder, paper powder, and other paper surface foreign matter caused by toner failure

Cause: The paper consists of fibers, fillers, and paints. During proofing in the printing process, paper hair, paper dust, and other foreign materials on the paper (including paper scraps left by cutting paper) will be adhered to the plate by the ink due to excessive ink viscosity or loose paper. Or on the blanket, there will be toner failure when printing. Offset printing machine

Solution: 1 First, print a layer of white ink on white paper, or print it without ink, remove loose paper, paper powder, or paper surface foreign matter, and then wash the material pharmaceutical packaging on the blanket with clean water. Only officially printed. 2 Add a small amount of detackifier to the ink to reduce the viscosity of the ink. 3 Clean the blanket and printing plate in time to remove paper, paper dust, or paper foreign matter in time.

Ink roller failure due to aging

Causes: The ink roller will crack when it ages. These cracks will often contain ink. After drying, it will form a DTP. When the ink is printed, it will cause ink failure.

Solution: Grind the ink roller or replace it with a new one.

Ink loss due to ink imbalance

Reason: If the water supply is too large or the pH of the fountain solution is too low during printing, the ink emulsification phenomenon will be more serious. The pigments and other particulate matter in the ink will be released from the ink, and under the effect of printing pressure, Stacked on the surface of the printing plate or blanket washing product packaging, thus forming ink failure.

The solution: 1 reduce the amount of water supply. 2 Adjust the pH of the fountain solution to control the degree of emulsification of the ink. 3 In the ink properly added 0 varnish to reduce the pigment particles segregation.

Dust or oil-induced toner chip failure

Cause: If the factory building and the machine stand are not clean, many dusting, oil stains, and dust will accumulate on the printing plate or the blanket, resulting in ink failure. Digital Printing

Solution: Clean the workshops and machines, and clean the ink roller, water roller and ink tank regularly. When cleaning the machine, pay special attention to whether the two ends of the ink roller are cleaned.