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Offset Printing Needs To Pay Attention To The Eight Major Matters

Author: Site Editor     Publish Time: 01-07-2022      Origin: Site

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1.Observation of sample sheets

Printing process, test printing to determine the amount of ink supply, water supply will always be some changes, should often be re-adjusted by sampling the print sample, generally 500-1000 sample 1, the focus is to observe the overprint and ink color of the print sample. Ink color check can generally compare the two sides of the print sample with the middle part, but also the print sample turn around for ink color comparison, and can be compared with the previous times to take the print sample. If there is a change, the ink supply system can be fine-tuned. Attention should also be paid to whether there is a change in the moisture of the layout. The rules of the check, especially the first color of the single-color machine to print the check, you can often take 20-30 print samples, the gripper collision Qi staggered, observe the rules of the line up and down whether the same, before the gauge, side gauge positioning is accurate. After a period of continuous printing, paper powder, paper hair and ink in the tiny ink skin and other dirt, easy to adhere to the printing plate or blanket, resulting in lines, text broken lines, lack of pen broken painting or graphics sticky dirty, such as such cases, should stop but the paper hair, ink skin and other dirt to prevent downtime caused by changes in ink shades, it is generally appropriate to put 8-10 over the version of ink-absorbing paper and then continue printing. At the same time, should often pay attention to check the print, observe the back of its sticky dirty phenomenon, the larger the graphic area, the thicker the ink layer of the print, should be taken to spray powder and drying plywood measures.

2.Cleaning rubber blanket

After several thousand sheets of continuous printing, due to the accumulation of paper powder on the rubber blanket, paper hair and ink skin, such as thickening, ink transferability is getting worse, the printing sample ink becomes shallow and rough, the level gradually unclear, blurred outline. At this time should immediately stop, clean the blanket. PrintBar rubber blanket cleaning reducer can not only play a clean rubber blanket role, but also can make the surface of the rubber cloth recovery, and restore its elasticity.

3.Clip in 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 post-process. The method is to clip the warning paper marked with eye-catching colors such as "scuffing" and "inadmissible overprinting" into the pile of paper.

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

Printing process, the printing plate should maintain a moderate amount of water. If the page water is large, the ink is seriously emulsified, the print loses its luster, the lines are faint, the ink dries slowly, the paper elongates, the overprint is not allowed; if the page water is too little, the blank part is easy to dirty, should be based on sampling or page brightness to observe changes in the page water, timely adjustment. When the amount of water is too large to reduce the speed of the water bucket; when the amount of water is not enough to speed up the speed of the water bucket roller.

5. Pay attention to the change of ink

(1) Pay attention to the ink in the ink hopper. The ink in the ink hopper flows naturally by its own weight, and the size of the ink output depends on the gap between the ink hopper and the ink hopper blade. Therefore, the amount of ink in the ink hopper directly affects the amount of ink output, and the amount of ink in the ink hopper must be maintained regularly to keep the ink output stable. Ink is thixotropic, you need to often use the ink shovel to stir the ink or install the stirrer, so that the ink to maintain good fluidity.

(2) pay attention to the ink color of the print. The ink color of the print will vary when the water supply, ink supply, workshop temperature and humidity, machine operation and other factors change slightly. Therefore, the printing process requires frequent sampling, will be compared with the standard ink color of the test print. In the printing process, the operator must adhere to the three diligent operation, that is, diligent inspection of the sheet, diligent observation of the layout of water, diligent stirring of ink in the ink hopper.

6. Pay attention to the changes in the printing plate

Pay attention to the printing plate shine at the shallow tone fine dot whether wear, and the need to replace the new version; pay attention to observe whether the layout has scratches, the printing plate is loose.

7. Measures to be taken in case of long-time shutdown

The following measures are required during long downtime such as waiting for plates and work breaks.

(1) to protect the printing plate. In the printing plate surface coated with gum Arabic, and take care not to leave bubbles on the layout, and the gum must not adhere to the rubber blanket.

(2) prevent the ink from drying. In order to prevent the ink in the ink hopper and ink rollers on the surface drying, you can spray drying inhibitor on the surface of the ink.

(3) Semi-finished products storage. Semi-finished products should be stored in an airtight, light-proof workshop compacted to avoid paper deformation, affecting overprinting.

8. Pay attention to the printing abnormalities in the operation of the printing machine

Should pay close attention to the possible abnormalities in the operation of the offset press, such as abnormal sounds from the machine during operation, the temperature of the bearings and frame, the overall or local vibration of the machine, and the blockage of the machine oil circuit. Once the abnormality occurs, it should be stopped in time for maintenance.

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