The culprit causing the imprinting

In the printing process, the phenomenon of imprinting deformation is commonplace. Based on past practical experience, various factors that cause imprinting deformation in the printing process are summarized below for reference by peers.

1. Plate factor

At present, the PS plates used in the printing industry are mostly based on aluminum plates, and a certain amount of zinc is added. In addition to having a certain tensile strength, it also has a certain degree of ductility. Under certain conditions, the tensile strength of the new PS is better than that of the new PS. With the printing of the new PS plate, the ductility is not obvious. If a plate made of a recycled PS plate is used, especially in the case of a large number of prints, this change can be clearly felt. With the increase of the number of prints, the entire printing plate extends from the middle along the two directions of the fixed printing plate, and the more the number of printings of the printing plate changes, the more obvious the printing plate becomes. Do not add backing paper to the back of the plate to maintain printing. If necessary, the plate must be discarded to ensure quality.

The main cause of this quality problem: After electrolysis of the PS plate, although no qualitative changes have occurred, the surface of the sand is significantly coarser than the new PS plateau, and the thickness and weight are also reduced. The thickness of the new PS plate is 0.3mm, and the thickness of the PS plate after electrolysis is sometimes less than 0.15mm. The tensile strength is naturally not as strong as the new PS plate, but the ductility is stronger than that of the new PS plate. When the operator loads the plate, it will pull the edge of the plate directly because it is too hard when tightened. The weight of the new PS version is 0.5kg per sheet, and most of the regenerated PS plates do not reach this weight, and some are even lower than 0.25kg. The plate thus produced has poor tensile strength and sometimes the entire plate can be elongated. More than 5mm, its scalability is naturally stronger than the PS version. Since most offset presses work at high speeds, the plates will be deformed and the prints on the plates will be deformed.

2. Blanket factor

The influence of the blanket on the distortion of the printed writing, the author believes that there are mainly the following factors.

Reason 1: The purchase of unqualified rubber blankets cannot reach the normal service life, lose its proper performance, and result in imprinting deformation during printing.
Solution: Replace the qualified blanket immediately.

Cause 2: The blanket is not installed properly, and loosening occurs halfway.
Solution: Reinstall the blanket.

Reason 3: Due to the operator's failure to clean the surface of the blanket in time (such as ink, etc.), a long time, the surface area of ​​the blanket has a thick layer of impurities, the surface hardening, can not be cleaned, absorbed during the printing process The moisture on the surface of the printing plate expands and the surface of the printing plate is deformed.
Solution: Clean up in time and replace the blanket when it cannot be cleaned.