Eight notes on how to achieve perfect printing are

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How to achieve perfect printing? "Eight notes" is worth knowing.

first, pay attention to the observation of the sample sheet

① sampling inspection in printing. Shortly after entering the official printing, there will be some changes in the ink supply and water supply determined at the beginning of printing, and frequent sampling inspection and readjustment should be carried out. When the printing speed remains unchanged and the ink supply and water supply are in a stable state, the sampling inspection shall be carried out according to the proportion of 500-1000 pieces/time per print

② clip in the warning note. In formal printing, as a mark, long and thin warning paper should be clamped in the place where the fault occurs, so as to facilitate the inspection in the subsequent process

II. Pay attention to the changes of water filling

① pay attention to the changes of water filling at the initial stage of official printing. There will be some changes in the amount of water added during the trial printing and after entering the official printing. You must pay attention to the adjustment of the water supply of the printing plate while observing whether the sample has ghosting and water shoulder

② pay attention to the change of water filling during the official printing process. Pay close attention to the influence of the heating of the main body of the machine and the ventilation condition in the workshop on the water filling. For alcohol dampening, pay attention to the cooling device of the wetting system, and control the temperature of the wetting liquid. Too little water filling will make the printing plate dirty; Too much water will cause ink emulsification, which will bring a series of problems. For example, the printed matter is Matt, the paper is stretched and overprinted inaccurately, and the drying of ink is delayed

III. pay attention to the change of ink

① pay attention to the ink of the ink bucket. The ink of the ink bucket comes out from the gap between the ink bucket roller and the ink bucket scraper, which is naturally squeezed out by the weight of the ink. Therefore, the amount of ink in the ink bucket directly affects the output of ink. Therefore, pay attention to keep a certain amount of ink in the ink bucket. In addition, printing inks have thixotropic properties. Placed in the ink bucket for a long time, the fluidity will gradually deteriorate. Therefore, you should often use an ink knife to stir in the ink bucket, or install an ink mixer

② prevent the ink from drying on the machine. During long-term shutdown, such as eating and rest, the ink on the ink roller and the ink surface in the ink bucket will dry. Dry inhibitors can be used to spray on places that need to be prevented from drying

③ pay attention to the uniformity of the ink, and the density of the printed matter changes depending on the water volume, room temperature and machine speed. It should be frequently compared with the standard sample. Pay attention to prevent uneven ink color

④ maintain the pH value of the wetting solution. After the auxiliary agent is added to the ink, it is easy to affect the pH value of the wetting solution. If the pH value increases, it is easy to cause the printing plate to get dirty, so special attention should be paid

IV. when D1 < 5, the dimensional deviation and appearance quality are qualified; Dirty surface

dirty back is the phenomenon that the ink on the surface of the printing sheet sticks to the back of the previous printing sheet due to the slow drying of the ink, the thick ink layer of the graphics and text, and the high smoothness of the paper

v. pay attention to the ghosting fault

the so-called ghosting is the dislocation of the image printed with a printing plate, and the double and triple images can be seen on the printing sheet. There are many reasons for ghosting, such as paper, teeth, roller, blanket, printing speed, ink viscosity and other factors are very complex. The following methods can be used to check the cause and deal with it

① print twice, observe the overprint accuracy, check and adjust the paper pulling force of the side gauge, paper feeding, paper pressing wheel and paper pressing machine parts

② check the tension of the blanket. The new blanket is easy to relax. Pay attention to tighten it in several times, but don't be too tight

③ check the cylinder lining and printing pressure

④ check the suitability of the paper. The paper has poor adaptability, especially the paper with waves in its mouth, which is prone to ghosting, so it should be checked

⑤ reduce the viscosity of the ink. The ink viscosity is high, and the paper cannot peel off the blanket smoothly, making the trailing part of the paper unstable, resulting in ghosting. The viscosity of the ink can be appropriately reduced

⑥ adjustment of teeth. Bad adjustment and improper maintenance of the teeth are a major cause of ghosting. Therefore, the adjustment, maintenance and inspection of the teeth should be done regularly, so that the market growth rate of the company can reach the level of 7% to 8%

VI. pay attention to check the overprinting situation

the new type of recycled plastic granulator is constantly optimized and updated. Take out 20~30 pieces of printing continuously, mainly using PP epdm-td10 or PP epdmtd20 modified polypropylene materials. Twist the paper edge a little after flushing, and check whether the front gauge and side gauge are accurately positioned (two overprinting checks can be carried out)

VII. Pay attention to other work

① supplement of ink, mixing and wetting liquid

② dirt removal operation. It is necessary to remove dirt because dirt such as ink residue, paper powder and paper wool are adsorbed on the printing plate or blanket and reflected on the paper. Generally, the dirt removal operation should be stopped. Unless there is a device that can remove dirt during operation. It is absolutely forbidden to remove dirt directly by hand during operation

③ clean the blanket, wipe the plate and apply glue. When ink, paper powder and powder spray accumulate on the blanket and affect the transfer of ink, it is necessary to stop the machine to clean the blanket and pay attention to safety during operation. Attention should also be paid to safety in plate erasing and gluing operations

④ pay attention to the abnormal phenomenon of the printing machine. Pay attention to the sound, heat, vibration, smell, etc. when the machine is running, often check the ammeter, and pay attention to the abnormal conditions of the printing machine

VIII. Pay attention to confirm the number of prints

when the printing is about to end, confirm whether the number of prints is consistent with the production construction order. If there is a shortage that needs to be supplemented, the production management personnel shall be notified and the supplement shall be arranged in time

[source: Cangnan printing and Packaging Association]

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