Cost control of the hottest newspaper printing ent

Cost control of newspaper printing enterprises

people who often read newspapers often find one or several thin lines that are significantly shallower than the printed text on some large-scale field pictures or decorative stripes on the newspaper. This is the so-called "ghost", most of which are "ghost without ink", causing the experimental machine to be unable to adjust to zero. Ghost refers to the impression or shadow of unknown origin

due to the strong timeliness and political nature of newspapers, short production cycle and fast printing speed, once there is a "ghost" phenomenon, it will seriously affect the printing quality and cause waste of raw materials. At least it will affect the image of individuals and companies, and at worst it will cause political accidents. To truly understand the causes of the "ghost of ink shortage", we also need to understand the composition of the ink supply system and the ink transmission mechanism of the printing press

1 function of ink supply system of printing machine

the ink supply system of newspaper rotary machine and general sheet fed offset press is composed of ink bucket, ink bucket roller, ink transfer roller, ink string roller, inking roller, etc. Sheet fed offset presses generally have 20 to 26 ink rollers, while rotary presses generally have only 7 to 11 ink rollers due to their high speed. If the ink supply speed cannot keep up, it will lead to insufficient ink supply. The work task of the ink supply system is simply two tasks: one is to quickly mix the ink from the ink bucket through the ink roller; Second, when the printing plate rotates every time, the inking roller has a comprehensive, uniform and appropriate amount of ink to the printing plate

as we all know, in order to make the ink transfer well, the following conditions must be met:

1) when the surfaces of two ink transfer pieces in contact with each other are separated, the ink layer breaks in the middle

2) compression deformation shall occur on one of the two transfer surfaces in contact with each other to ensure reliable contact between ink molecules and the transfer surface. In the ink delivery system of newspaper printing machine, the material of ink delivery roller is required to have good ink affinity, the viscosity of printing ink should be appropriate to ensure that the ink layer breaks in the middle, and the soft roller and hard roller should be set alternately, so that there can be an ideal contact between the ink and the delivery part, and the strength performance is 30% greater

2 "ghost" phenomenon and its solutions

according to experience and analysis of newspapers, the ghost is mainly caused by the following reasons:

1) poor pressure debugging

the printing pressure and the contact pressure between various ink rollers are not in the best printing state, resulting in local ink shortage and the formation of "ghost". The ink rollers should be in good contact with each other to ensure the normal transmission of ink. The contact should not be too light or too heavy with the progress of science and technology. Generally speaking, thin solid lines on the layout are not easy to produce "ghost", but due to the improper pressure adjustment between the ink rollers, it will affect the normal ink transmission and water supply, and also produce "ghost". As long as the pressure is readjusted to ensure the smooth and uniform transmission of ink, the "ghost" phenomenon can be eliminated. However, if the printing pressure is too light, local weakness will appear in the print, and water ripples will appear in serious cases

2) the drum gear and bearing gear are worn

the Journal of the printer drum shaft is equipped with helical gears to transmit power and accurately position. Due to the fast running speed, long working time and serious natural wear of the newspaper printer, it is easy to cause excessive gear meshing clearance, resulting in mutual slip between the longitudinal rollers, and slight contact dislocation between the gears, resulting in "ghost". The solution to this problem is to replace gears and bearings; Reduce the center distance of the drum to reduce the drum clearance

3) the blanket and the printing plate are not tightened

the blanket is not tightened, resulting in the rubber drum cannot be reset in time after being pressed or the blanket is skewed during cutting, resulting in "ghost". The printing plate can also cause "ghost" due to careless work and no tension. Check carefully during work, and these faults can be basically eliminated

another thing to note is that

4) newspaper layout design needs to be improved

use thick solid lines, regional isolation lines or decorative lines to design the layout. These lines are perpendicular to the direction of the ink roller of the printer, and there are pictures on both sides of the lines or shallow decorative strips perpendicular to the ink roller, so it is easy to produce "ghosts" on these decorative strips. The reason is that thick lines consume a lot of ink locally in printing, and there are often blank parts on both sides of the lines. Due to the structural characteristics of the newspaper printing machine, the local ink roller can not supplement the required ink in time, resulting in "ghost" phenomenon. As long as we are familiar with the above principles and operate correctly, we can reduce the occurrence of "ghosts"

reprinted from: printed in Guangzhou