What are the factors that make gravure press printing products good or bad?
First, the scraper
Only the scraper can scrape the excess ink (ink on the non-printing surface) of the gravure press to print a good product. However, if you want to scrape the excess ink, and do not appear dirty, running ink (running color), knife line, you must adjust the hardness, height and angle of the blade placement. How to adjust is more appropriate? The usual experience is:
1. The softness and hardness of the scraper device should be moderate. The hardness of the squeegee also affects the quality of the print. The scraper is iron, and the gravure plate is chrome-plated on the surface of the copper drum. Since the hardness of copper is 200-300 HV and the hardness of chromium is 700-900 HV, it is better to choose a squeegee with a hardness of 450-600 HV, so that the plate is not damaged. It is not easy to leave a knife mark, and it can also scrape off excess ink on the layout.
2. The scraper should be placed at an appropriate height. The scraper should be adjusted according to the printing speed. The printing speed is fast, the distance from the stamping point is far, the printing speed is slow, and the stamping point is closer.
3. The angle at which the scraper is placed should be appropriate. In general, the mounting angle of the blade is preferably 55 to 65 degrees.
Second, the embossing rubber roller
The hardness and pressure of the gravure press rubber roller material directly affect the amount of ink on the printed matter.
1. The hardness of the material of the stamping roller affects the amount of ink, the material of the rubber roller is hard and the amount of ink is small, and the material of the rubber roller is soft.
2. The pressure of the rubber roller is large and the amount of ink is large. The pressure of the rubber roller is small, and the amount of ink is small.
3, the printing plate pattern is deep, the material of the embossing rubber roller needs to be harder; the printing plate pattern is shallow, and the material of the embossing rubber roller needs to be soft.
4, the printing speed is fast, the material of the embossing rubber roller needs to be harder; the printing speed is slow, and the embossing rubber roller with soft material needs to be selected.
Third, the ink supply system
In order to ensure the smooth printing and the consistency of the ink color of the printing, the ink supply system circulation of the printing machine must be good, and the ink should be kept flowing at all times.
1. Always maintain the consistency of the ink viscosity, timing measurement, and timing the solvent.
2. New and old inks should be blended in proportion. The use of a composite solvent prevents the proportion of the ink components from being out of adjustment, and precipitation and anti-roughness occur.
3, it is best to use ink pump and stir bar to carry out ink circulation, pay attention to the ink bucket should not be too large, the ink tank size should be moderate.
Fourth, the drying box
One of the keys to increasing the printing speed of the gravure printing machine is the effect of the oven. The ink is dried by hot air, not by heating. And the higher the heat, the less ink on the print is easier to dry. Why?
1. If the temperature is too high, the surface of the ink will be conjuncted, causing the phenomenon of dryness in the surface.
2. The solvent with low boiling point in the ink volatilizes prematurely, the solvent with high boiling point remains, and the drying speed is slowed down. Then the wind of the drying box is required to be greater than the heat, and the temperature can be 40~50 °C. The wind can't be directly blown on the film. The heat can't be directly baked on the film surface. It has good air-exhausting ability. It can't run on the printing plate and the ink tank. The drying box has better secondary air return performance. It is necessary to effectively prevent the printed matter from drying out and infecting bad odors.