What is the quality of the gravure press print?
The gravure printing machine is printed by circular pressing and direct printing. The printing plate is directly formed on the plate cylinder, and is inked by ink or ink jet. There is no ink distribution mechanism. Due to the thick ink layer, a fast-drying ink with high volatility is used, and a drying device is required.
When the gravure printing machine is working, the four elements of the construction and operation of the printing machine determine the quality of the printed matter. These four elements are: scraper, embossing roller, ink supply system, drying oven.
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.