The pressure, sharpness, and contact position of the ink scraper in the oil cup all have an impact on the printing quality. Reasonably adjusting these factors according to actual needs can solve many printing problems.
The sharpness of the knife
The sharpness of a knife depends on whether it is new, the angle of the blade when sharpening, and the type of sandpaper (oilstone) used. The appropriate sharpness of a knife should be able to effectively scrape off ink without producing blade threads. Overly sharp scrapers often produce blade marks and wear down the printing plate.
pressure
The factors that affect the pressure of the oil cup scraper are the size of the cylinder pressure, the difference between the hard and soft blades, and the angle at which the oil cup scraper intersects with the printing plate. The greater the slope, the greater the pressure. Excessive pressure can reduce the transfer rate of ink and cause significant wear on the printing plate and blades; Too little pressure can easily cause dirty plates or scraper lines.
The distance between the oil cup scraper and the printing plate
Reducing the distance between the scraper and the printing plate is beneficial for improving the ink transfer rate, but it is also prone to producing dirty plates; On the contrary, it can effectively solve the problem of dirty plates and avoid some small line marks, but it will reduce the ink transfer rate.
The flatness of the knife
The flatness and warping of the knife mainly depend on the installation method, but it may also be related to foreign objects stuck in the tool holder groove or on the blade or lining.
When the flatness of the knife is poor, it will cause some water droplet like marks on the edge of the printing surface, or occasional intermittent line marks. Some people believe that rough ink and poor ink fluidity are the reasons for the above phenomenon, but in fact, uneven knives can also cause this situation.
The movement of the ink scraper in the oil cup
When there are line marks in printing, one is that it causes plate damage, and the other is that the scraper is not sharp enough. However, another reason is that there are foreign objects sticking behind the blade. The solution is to move the oil cup scraper back and forth, up and down, in order to shake off the adhesive. If it cannot be shaken off, the oil cup scraper can only be stopped.
The left and right movement of the oil cup scraper blade plays an important role in reducing scraper lines, improving scraper utilization, and reducing plate wear. If the ink scraper of the oil cup moves abnormally, measures should be taken to improve it.
Another challenge is related to the scraper, and many people misunderstand it as caused by ink. This refers to the occasional appearance of dozens of irregular lines of varying lengths, resembling ink stacks. Unlike scraper lines, it is not continuous but intermittent, which is actually caused by insufficient pressure or sharpness of the scraper.