1. Observation proofs

During the printing process, the amount of ink supply and water supply determined during the trial printing will always change. You should often check the print samples to conduct a high-speed sample of 500 to 1000 sheets. The key is to observe the overprint and ink color of the print . Ink color inspection can generally compare the two sides of the printed sample with the middle part, and can also compare the ink color of the printed sample head, and can be compared with the previous printed samples. If there are changes, the ink supply system can be fine-tuned. Also pay attention to whether there is any change in the moisture content of the layout. Rule inspection, especially for the first color of single-color machine printing, can often take 20 ~ 30 print samples, stagger their grips, observe whether the rule line is consistent, and whether the front and side regulations are positioned accurately . After continuous printing for a period of time, dirt such as paper powder, paper wool and fine ink skin in the ink can easily adhere to the printing plate or blanket, resulting in broken lines, text, missing pens, broken pictures or graphics Sticky, if there is such a situation, the paper wool, ink skin and other contaminants should be wiped down to prevent the color change of the ink color caused by the shutdown. Generally, it is better to put 8 ~ 10 sheets of ink absorption paper before printing. At the same time, you should always pay attention to check the printed products to see if there is any sticky dirt on the back. For the printed products with large graphic areas and thick ink layers, dusting and plywood measures should be taken.

2. Cleaning blanket

After continuously printing thousands of sheets, as the paper powder, paper wool and ink skin accumulated on the blanket become thicker and thicker, the transferability of the ink becomes worse and worse, the print ink becomes light and rough, and the level is gradually unclear. Blurred silhouette. At this time, the machine should be stopped immediately to clean the blanket. There are two methods for cleaning the blanket: manual and automatic. When cleaning by hand, wipe with a cloth soaked in gasoline while jogging the machine. After the dirt is dissolved, remove the dirt with a clean cloth. During automatic cleaning, first pull the handle of the cleaning device to make the cleaning roller contact with the rubber roller, then inject gasoline through the oil injection tube to the pressure roller, clean the rubber cloth, the dirty oil that has been cleaned is transferred to the active roller, and finally it is scraped Scrape into the oil tank. At the same time, care should be taken to keep the blanket flat and there should be no pits.

3. Clip warning paper

During the printing process, the place where the fault is found should be marked, so as to focus on the inspection in the subsequent process. The method is to clip the warning paper marked with the words "Dirty" and "Inappropriate Overprint" in bold colors in the pile of paper.

4. Pay attention to the changes in the amount of water in the layout

During the printing process, the printing plate should maintain a moderate amount of water. If the amount of water on the plate is large, the ink is seriously emulsified, the blot is tarnished, the lines are dull, the ink dries slowly, the paper is elongated, and the overprint is not accurate; if the amount of water on the plate is too small, the blank part is easy to get dirty. Water volume changes should be adjusted in time. When the amount of water is too large, the speed of the bucket should be reduced; when the amount of water is insufficient, the speed of the bucket roller should be increased.

5. Pay attention to the change of ink

(1) Pay attention to the ink in the ink fountain. The ink in the ink fountain will naturally flow by its own weight, and the amount of ink output depends on the gap between the ink fountain and the ink fountain blade. Therefore, the amount of ink contained in the ink fountain directly affects the amount of ink discharged. In order to maintain the stability of the amount of ink discharged, the amount of ink in the ink fountain must be constantly maintained. In addition, the ink has thixotropy, it is necessary to often use an ink shovel to stir the ink or install a stirrer, so that the ink maintains good fluidity.

(2) Pay attention to the ink color of the printed product. The ink color of the printed product will be different when the water supply, ink supply, workshop temperature and humidity, machine operation and other factors change slightly. Therefore, it is necessary to sample frequently during the printing process and compare it with the standard ink color of the trial printing.

In short, in the printing process, the operator must insist on three-time operation, that is, check the printed sheet, observe the water volume of the plate, and stir the ink in the ink fountain. In addition, the ink on the ink roller should be cleaned when changing colors, especially when dark ink is changed to light ink.

6. Note the changes in the printing plate

Pay attention to observe whether the light adjustment fine dots on the shiny part of the printing plate are worn, and you need to replace the new version; pay attention to whether there are scratches on the plate surface and whether the printing plate is loose.

7. Measures to be taken during prolonged downtime

When waiting for a long period of downtime, such as waiting for a version or working break, the following measures need to be taken:

(1) Protect the printing plate. Apply gum arabic to the surface of the printing plate, taking care not to leave air bubbles on the surface of the plate, and the glue must never stick to the blanket.

(2) Prevent ink from drying. In order to prevent the surface of the ink in the ink fountain and the ink roller from drying, a drying inhibitor can be sprayed on the surface of the ink.

(3) Storage of semi-finished products. The semi-finished products should be stored and compacted in a closed, light-proof workshop to avoid paper deformation and affect overprinting.

8. Pay attention to the abnormal printing phenomenon in the operation of the printing press

Attention should be paid to the abnormalities that may occur during the operation of the offset press, such as the abnormal sounds emitted by the machine in the Second Light Transportation Bureau, the temperature at the bearing and the frame, the overall or local vibration of the machine, and the blockage of the machine oil path. Once an abnormality occurs, it should be shut down for maintenance in time.

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