The four elements of the gravure printing machine, you are the captain of Niu Bai
In gravure printing, the quality of the printed matter is determined by the four major elements of the structure and operation of the printing press. The four major elements are: doctor blade, embossed rubber roller, ink supply system, and drying box.
1. Scraper
Only the scraper can scrape the excess ink (the ink on the non-printing surface) of the gravure printing machine to print a good product. However, if you want to scrape the extra ink clean, without hanging dirt, running ink (running color), and knife line, you must adjust the hardness, height, and angle of the scraper to make appropriate adjustments. How to adjust more appropriately? The usual experience is:
1. The hardness of the scraper device and the elasticity of the scraper should be moderate. The hardness of the doctor blade also affects the print quality. The squeegee is iron, and the gravure is chrome-plated on the surface of the copper cylinder. Because the hardness of copper is 200-300HV and the hardness of chromium is 700-900HV, it is best to choose a squeegee with a hardness of 450-600HV, so that it will not damage the printing plate , And not easy to leave a knife mark, you can also scrape off the excess ink on the layout.
2. The scraper needs to be placed at an appropriate height. The scraper should be adjusted according to the printing speed. The printing speed is fast, farther from the imprinting point, the printing speed is slower, and it is better from the imprinting point.
3. The angle of the scraper should be suitable. In general, the installation contact angle of the scraper is most suitable from 55 ° to 65 °.
2. Imprint rubber roller
The hardness and pressure of the material of the rubber roller of the gravure printing machine directly affect the amount of ink on the printed matter.
1. The hardness of the embossed rubber roller material affects the amount of inking. The material of the rubber roller has a small amount of hard ink and the material of the rubber roller has a large amount of ink.
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 light, the material of the embossing rubber roller needs to be softer.
4. The printing speed is fast, the material of the embossing rubber roller needs to be harder; the printing speed is slow, the embossing rubber roller of softer material needs to be selected.
3. Ink supply system
In order to ensure the smooth progress of printing and the consistency of the ink color of the printed product, the ink supply system of the printing machine must have a good circulation, and the ink must be kept in constant flow at all times.
1. Always maintain the consistency of ink viscosity, measure regularly, and add solvent regularly.
2. New and old inks should be blended and used in proportion. The use of a compound solvent prevents the ratio of ink components from becoming unbalanced and causing precipitation and anti-coarse phenomena.
3. It is best to use an ink pump and an agitator to circulate the ink. Note that the ink hopper should not be too large and the size of the ink tank should be moderate.
4. Drying box
One of the keys to the printing speed of the gravure printing machine is the quality of the oven. The ink is dried by hot air, not by heating. And the higher the heat, the harder the ink on the printed matter is to dry, why?
1. If the temperature is too high, the ink surface will be conjunctival, which will cause the phenomenon of false drying in the surface drying.
2. The low boiling point solvent in the ink volatilizes prematurely, the high boiling point solvent remains, and the drying speed is slowed down. Then it is required that the air in the drying box is greater than the heat, and the temperature can be between 40 and 50 ° C. The wind can not be directly blown on the film, the heat cannot be directly baked on the film surface, it must have good exhaust performance, can not run on the printing plate and ink tank, and the drying oven has better secondary air return performance. It is necessary to effectively prevent false drying of printed materials and infections.
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