I. Watch out for sample sheets
Sampling inspection in printing. Shortly after entering the formal printing, there will be some changes in the affirmative ink supply and water supply at the time of printing. Sampling inspection should be carried out frequently and readjustment should be stopped. When the printing speed remains unchanged and the ink supply and water supply are stable, the sampling inspection shall be stopped at the ratio of 500 to 1000 sheets per printing.
(2) Insert warning note. In formal printing, as a mark, a long warning note should be inserted into the center of the breakdown so that the inspection can be stopped in the later process.
2. Pay attention to the change of water supply
(1) Pay attention to the change of water supply in the initial stage of formal printing. There will be some changes in the amount of water used in the trial printing and the amount of water used after entering the formal printing. We must pay attention to the duplication of sample sheets and water carriers, as well as the adjustment of the amount of water supplied to the printing plate.
(2) Pay attention to the change of water supply in the process of formal printing. Alcohol wetting plate should pay close attention to the cooling installation of wetting system, control the temperature of wetting liquid, too little water will make the printing plate dirty; too much water will cause ink emulsification, which will bring a series of problems. For example, the gloss of printing products, paper flexibility and improper overprinting, delay the dryness of ink, etc.
3. Pay attention to the change of ink
Watch out for the ink in the ink bucket. Ink from the bucket roll and the bucket scraper gap between the ink, is the weight of the ink and is naturally squeezed out. Therefore, the amount of ink in ink bucket directly affects the output of ink. Therefore, we should pay attention to letting ink bucket adhere to a certain amount of ink. In addition, printing ink has thixotropic properties. If placed in the ink bucket for a long time, the activity will gradually deteriorate. Therefore, the ink knife should be often used to stir in the ink bucket, or the ink mixer should be installed.
(2) Avoid the dullness of the ink on the machine. When the machine stops for a long time, such as eating and resting, the ink on the roller and the ink in the ink bucket will be dull. It can be sprayed with a dull inhibitor to avoid the dull place where the demand is.
(3) Pay attention to the average ink, the density of printed matter varies depending on the amount of water, room temperature and machine speed. It should be checked regularly with the standard sample. Be careful to avoid ink inequality.
(4) Adhere to the pH value of the wetting solution. When the auxiliary agent is added to the ink, it will easily affect the pH value of the wetting solution. If the pH value increases, the printing plate will become dirty, so special attention should be paid to it.
4. Pay attention to the dirty rubbing on the opposite side
The reason why the ink is dull and slow, the ink layer is too thick and the paper is smooth is that the ink on the surface of the printed sheet sticks to the reverse of the previous one.
5. Pay attention to the problem of duplication
The so-called duplication is to use a plate to print the image offset, in the printing can see double, triple images. There are many reasons for duplication, such as paper, teeth, drum, rubber cloth, printing speed, ink viscosity and other factors are very complex. The following methods can be used to examine the cause and dispose of it.
(1) Printing twice to check the accuracy of overprint, drawing force of opposite gauge, check and adjust feeding, pressing wheel and pressing machine parts.
Check the tension of rubber cloth, new rubber cloth is easy to relax, pay attention to tightening step by step, but not too tight.
Check drum liner and printing pressure.
(4) Check the paper suitability. Paper with poor adaptability, especially the paper with wavy mouth, is prone to heavy shadow, so check should be stopped.
Reduce the viscosity of ink. Ink viscosity is high, paper can't peel off rubber cloth smoothly, so that the paper's trailing part is unstable, resulting in ghosting. It can reduce the viscosity of ink properly.
The adjustment of teeth. Poor adjustment and improper maintenance of teeth are the main reasons for the formation of double shadow. Therefore, we should regularly do a good job in the regulation and maintenance of teeth, so that they often adhere to good working conditions.
6. Pay attention to checking the overprint status
Continuously take out 20 to 30 sheets of prints, after finishing, twist the edge of the paper a little, check whether the front gauge and side gauge can be positioned accurately (can stop two overprinting checks).
7. Pay attention to other work
(1) Ink supplementation, stirring and wetting fluid supplementation.
(2) Dirty removal. It is necessary to stop dirty removal because the ink residue, paper powder, paper wool and other stolen goods are adsorbed on the printing plate or rubber cloth and reflected on the paper. Dirty removal operations should generally be stopped. Unless there are installations that can remove dirt during operation. It is absolutely forbidden to use hands to remove dirt directly during operation.
3. Cleaning rubber cloth, erasing and gluing operations. When ink, paper powder and spray powder accumulate on rubber cloth and affect the transfer of ink, it is necessary to stop the machine to clean rubber cloth, and pay attention to safety during operation. Rubbing and gluing operations should also pay attention to safety.
Pay attention to abnormal phenomena of printing press. Pay attention to the sound, heat, vibration and breath when the machine is running. Check the ammeter frequently and pay attention to the abnormal condition of the printing press.
8. Be careful to confirm the print
When printing will be finished, it should be confirmed whether the printing number is in line with the consumption construction list. Consumption management personnel should be notified if there is a shortage to be reprinted, and the reprinting should be arranged in time.
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