Magnetic Printing Technology and Mechanical Discussion--Lithographic Printing (4)

(IV) Lithographic Printing Process

1. Lithographic variables

Lithography is different from letterpress printing and gravure printing. The entire lithography process involves a wide range of knowledge. Piping workers must have some knowledge of physics, chemistry, electronics, color science, printing machinery, and aesthetics. Because the lithography process is a comprehensive science combined with multiple disciplines, the technology of the process is strong, and there are many variables in the printing process. In the printing process, the following problems are generally solved.

(1) Control of dampening solution One of the characteristics of mastering lithography is that it is inseparable from water. Correct use of dampening solution is a basic problem of plain printing. For example, the relationship between water and printing plates, the relationship between water and ink, the relationship between water and printed paper, etc., and the correct adjustment of these relationships play a very important role in ensuring the quality of printed products.

(2) Applicability of the ink The printability of the ink includes the viscosity, fluidity, and dryness of the ink. There are also ink colors, the use of printing ink auxiliary materials, the relationship between ink and printed paper, and so on.

(3) Suitability of paper The suitability of paper includes: ink absorption, smoothness, opacity, acidity and alkalinity of paper, water content and elasticity of paper, and the like.

(4) Use and control of printing machinery In addition to the correct adjustment of the printing machinery, there are also the printing pressure, the contact pressure between the ink roller and the plate, and the contact pressure between the water roller and the plate.

(5) Changes in the printing environment During the printing process, due to changes in the surrounding environment, the complexity of the printing process will increase. Such as turbidity, relative humidity changes will change the printing ink drying, fluidity; paper moisture content changes will affect the correctness of multi-color overprint; due to different day and night light, the operator must be based on the ink color, hue Such as adjusting the printing ink color.

(6)Magnetic ink characteristics The pigments of magnetic inks are generally hydrophilic, so they are prone to emulsification. This not only fails to obtain good prints, but also weakens the magnetic properties of printed parts. Bad influence.

In short, the lithography process is more complicated. To obtain high-quality prints, it is necessary to solve various complex and contradictory phenomena that appear in the printing process. Therefore, the quality of lithography depends to a large extent on the scientific knowledge and operational proficiency of the printing workers. Therefore, we must master the laws of the lithographic printing process, and at the same time must eliminate all kinds of failures in the printing process according to local conditions in order to reproduce high-quality prints. The factors involved in lithography are shown in Figure 2-29.

2. Lithography process

The whole process of the entire lithography process, including plate making (from the original to the original), printing (from receipt of the original, printing to the finished product), packaging and delivery (including the quality inspection of finished products, slitting, packaging products ) Three other processes. From the point of view of printing, it refers to the processes of printing, papermaking, cutting, transfer of ink, and water roller oversealing, in addition to printing, from the time the original is received to the finished printed product.