Influence of ink knife on print quality in the hot

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The impact of ink knife on the quality of printed matter in printing

the pressure, sharpness and contact position with the plate of the scraper all have an impact on the printing quality. According to the actual needs, reasonable adjustment of these factors can solve many problems in printing

1. Pressure

the factors that affect the pressure of the doctor blade are the size of the cylinder pressure, the difference between the hard and soft blades, the angle of the doctor blade and the printing plate, drawing the new future of the industry, etc. the greater the inclination, the greater the pressure. Excessive pressure will reduce the transfer rate of ink and cause greater wear to the printing plate and blade; Too little pressure is prone to dirty version or scraper line

2. Sharpness of the knife

the sharpness of the knife depends on whether it is new, the blade angle when sharpening, the model of sandpaper (oilstone) used, etc. The suitable sharpness of the knife should be that it can effectively scrape the ink without producing knife threads. Too sharp scrapers are often prone to produce traces of knife threads and wear plates at the same time

3. The distance between the doctor blade and the printing plate

the reduction of the distance between the doctor blade and the printing plate is conducive to improving the ink transfer rate, but it is easy to produce dirty plates; On the contrary, it can effectively solve the dirty version and avoid some small line marks, but it will reduce the ink transfer rate

4. The flatness of the knife

the flatness and warpage of the knife mainly depend on the installation method. Of course, it may also be related to the foreign matters stuck in the knife rest groove or on the blade and lining

when the flatness of the knife is poor, there will be some bead like marks on the edge of the printing surface, or intermittent line marks from time to time to improve efficiency and speed. Some people think that the above phenomenon occurs only when the ink is rough and the ink fluidity is not good. In fact, this situation also occurs when the knife is uneven

5. The movement of the doctor blade

the left-right movement of the doctor blade plays an important role in reducing the scraping. China's plastic machinery enterprises have increased the development of emerging markets for extruders in recent years. The doctor blade has endowed the material vitality line, improved the utilization rate of the doctor blade, and reduced the wear of the plate. If the doctor blade moves abnormally, find a way to improve it

when there are line marks in printing, one is to cause plate damage, and the other is that the scraper is not sharp. However, another reason is that there are foreign objects sticking behind the blade. The solution is to move the doctor blade up and down in order to get rid of the adhesive. If you can't get rid of it, you can only stop and wipe the doctor blade

another problem is related to the scraper, and many people misunderstand it is caused by ink. This means that sometimes there are dozens of irregular line marks of different lengths, which look like a stack of ink. Unlike the scraper line, it is not continuous, but sometimes non-existent. This is actually caused by the pressure of the scraper is too small or the scraper is not sharp enough

the above several indicators of scraper have both differences and similarities. When solving specific problems, one of them can be used, and sometimes it needs comprehensive application to completely solve the problem. For example, when there are some intermittent ink lines, it can be solved either by increasing the pressure or by sharpening the knife; When there is a serious dirty version, several aspects need to be combined and used; First, use a sharp blade, second, increase the pressure, and third, increase the distance between the scraper and the contact side

when the scraper is seriously worn and cannot be polished with sandpaper and oilstone, it can be polished with a special grinder, which can be reused for several times, greatly reducing the cost of the scraper

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